[ascl:1011.003]
ZPEG: An Extension of the Galaxy Evolution Model PEGASE.2

Photometric redshifts are estimated on the basis of template scenarios with the help of the code ZPEG, an extension of the galaxy evolution model PEGASE.2 and available on the PEGASE web site. The spectral energy distribution (SED) templates are computed for nine spectral types including starburst, irregular, spiral and elliptical. Dust, extinction and metal effects are coherently taken into account, depending on evolution scenarios. The sensitivity of results to adding near-infrared colors and IGM absorption is analyzed. A comparison with results of other models without evolution measures the evolution factor which systematically increases the estimated photometric redshift values by $Delta z$ > 0.2 for z > 1.5. Moreover we systematically check that the evolution scenarios match observational standard templates of nearby galaxies, implying an age constraint of the stellar population at z=0 for each type. The respect of this constraint makes it possible to significantly improve the accuracy of photometric redshifts by decreasing the well-known degeneracy problem. The method is applied to the HDF-N sample. From fits on SED templates by a $chi^2$-minimization procedure, not only is the photometric redshift derived but also the corresponding spectral type and the formation redshift $z_for$ when stars first formed. Early epochs of galaxy formation z > 5 are found from this new method and results are compared to faint galaxy count interpretations.

[ascl:1202.002]
ZODIPIC: Zodiacal Cloud Image Synthesis

ZODIPIC synthesizes images of exozodiacal clouds. As a default, ZODIPIC creates an image of the solar zodiacal cloud as seen from 10 pc, but it contains many parameters that are tweakable from the command line, making it a handy general-purpose model for optically-thin debris disks that yields both accurate images and photometric information simultaneously. Written in IDL, ZODIPIC includes dust with real optical constants, user-specified dust maps and can compute images as seen through a linear polarizer.

[ascl:1511.022]
ZInCo: Zoomed Initial Conditions

ZInCo manipulates existing initial conditions (ICs) compatible with GADGET-2/3 (ascl:0003.001) ICs, allowing different flavors of zoom-in simulations rather then producing new ICs from scratch. The code can manipulate initial conditions with multiple types of particles, unlike the vast majority of zoom-in ICs codes available, preserving their properties and random field. This allows ZInCo to take advantage of other codes that produce ICs featuring a broad range of different cosmologies; it can be used also on existing ICs even in the unlikely case nothing is known about their properties. The code is written in C++ and parallelized using MPI.

[ascl:1102.028]
ZEUS-MP/2: Computational Fluid Dynamics Code

Hayes, John C.; Norman, Michael L.; Fiedler, Robert A.; Bordner, James O.; Li, Pak Shing; Clark, Stephen E.; Ud-Doula, Asif; Mac Low, Mordecai-Mark

ZEUS-MP is a multiphysics, massively parallel, message-passing implementation of the ZEUS code. ZEUS-MP offers an MHD algorithm that is better suited for multidimensional flows than the ZEUS-2D module by virtue of modifications to the method of characteristics scheme first suggested by Hawley & Stone. This MHD module is shown to compare quite favorably to the TVD scheme described by Ryu et al. ZEUS-MP is the first publicly available ZEUS code to allow the advection of multiple chemical (or nuclear) species. Radiation hydrodynamic simulations are enabled via an implicit flux-limited radiation diffusion (FLD) module. The hydrodynamic, MHD, and FLD modules can be used, singly or in concert, in one, two, or three space dimensions. In addition, so-called 1.5D and 2.5D grids, in which the "half-D'' denotes a symmetry axis along which a constant but nonzero value of velocity or magnetic field is evolved, are supported. Self-gravity can be included either through the assumption of a GM/r potential or through a solution of Poisson's equation using one of three linear solver packages (conjugate gradient, multigrid, and FFT) provided for that purpose. Point-mass potentials are also supported.

Because ZEUS-MP is designed for large simulations on parallel computing platforms, considerable attention is paid to the parallel performance characteristics of each module in the code. Strong-scaling tests involving pure hydrodynamics (with and without self-gravity), MHD, and RHD are performed in which large problems (2563 zones) are distributed among as many as 1024 processors of an IBM SP3. Parallel efficiency is a strong function of the amount of communication required between processors in a given algorithm, but all modules are shown to scale well on up to 1024 processors for the chosen fixed problem size.

[ascl:1306.014]
ZEUS-2D: Simulation of fluid dynamical flows

ZEUS-2D is a hydrodynamics code based on ZEUS which adds a covariant differencing formalism and algorithms for compressible hydrodynamics, MHD, and radiation hydrodynamics (using flux-limited diffusion) in Cartesian, cylindrical, or spherical polar coordinates.

[ascl:1102.027]
ZENO: N-body and SPH Simulation Codes

The ZENO software package integrates N-body and SPH simulation codes with a large array of programs to generate initial conditions and analyze numerical simulations. Written in C, the ZENO system is portable between Mac, Linux, and Unix platforms. It is in active use at the Institute for Astronomy (IfA), at NRAO, and possibly elsewhere.

Zeno programs can perform a wide range of simulation and analysis tasks. While many of these programs were first created for specific projects, they embody algorithms of general applicability and embrace a modular design strategy, so existing code is easily applied to new tasks. Major elements of the system include structured data file utilities facilitate basic operations on binary data, including import/export of ZENO data to other systems; snapshot generation routines to create particle distributions with various properties; systems with user-specified density profiles can be realized in collisionless or gaseous form; multiple spherical and disk components may be set up in mutual equilibrium; and snapshot manipulation routines permit the user to sift, sort, and combine particle arrays, translate and rotate particle configurations, and assign new values to data fields associated with each particle.

Simulation codes include both pure N-body and combined N-body/SPH programs. Pure N-body codes are available in both uniprocessor and parallel versions. SPH codes offer a wide range of options for gas physics, including isothermal, adiabatic, and radiating models. Snapshot analysis programs calculate temporal averages, evaluate particle statistics, measure shapes and density profiles, compute kinematic properties, and identify and track objects in particle distributions. Visualization programs generate interactive displays and produce still images and videos of particle distributions; the user may specify arbitrary color schemes and viewing transformations.

[ascl:1512.016]
ZeldovichRecon: Halo correlation function using the Zeldovich approximation

ZeldovichRecon computes the halo correlation function using the Zeldovich approximation. It includes 3 variants:

- zelrecon.cpp, which computes the various contributions to the correlation function;

- zelrecon_ctypes.cpp, which is designed to be called from Python using the ctypes library; and

- a version which implements the "ZEFT" formalism of "A Lagrangian effective field theory" [arxiv:1506.05264] including the alpha term described in that paper.

[ascl:1605.016]
zeldovich-PLT: Zel'dovich approximation initial conditions generator

zeldovich-PLT generates Zel'dovich approximation (ZA) initial conditions (i.e. first-order Lagrangian perturbation theory) for cosmological N-body simulations, optionally applying particle linear theory (PLT) corrections.

[ascl:1110.005]
ZEBRA: Zurich Extragalactic Bayesian Redshift Analyzer

The current version of the Zurich Extragalactic Bayesian Redshift Analyzer (ZEBRA) combines and extends several of the classical approaches to produce accurate photometric redshifts down to faint magnitudes. In particular, ZEBRA uses the template-fitting approach to produce Maximum Likelihood and Bayesian redshift estimates based on: (1.) An automatic iterative technique to correct the original set of galaxy templates to best represent the SEDs of real galaxies at different redshifts; (2.) A training set of spectroscopic redshifts for a small fraction of the photometric sample; and (3.) An iterative technique for Bayesian redshift estimates, which extracts the full two-dimensional redshift and template probability function for each galaxy.

[ascl:1404.002]
ZDCF: Z-Transformed Discrete Correlation Function

The cross-correlation function (CCF) is commonly employed in the study of AGN, where it is used to probe the structure of the broad line region by line reverberation, to study the continuum emission mechanism by correlating multi-waveband light curves and to seek correlations between the variability and other AGN properties. The z -transformed discrete correlation function (ZDCF) is a method for estimating the CCF of sparse, unevenly sampled light curves. Unlike the commonly used interpolation method, it does not assume that the light curves are smooth and it does provide errors on its estimates.

[ascl:1807.017]
ZBARYCORR: Barycentric redshift calculator

ZBARYCORR determines the barycentric redshift (*z _{B}*) for a given star. It calculates the positions and velocities of solar system objects, applies the rotation, precession, nutation, and polar motion of the Earth, applies the stellar motion using the Markwardt library (ascl:1807.016), Shapiro delay, and light-travel term, and finally calculates the quantity

[ascl:1607.012]
ZASPE: Zonal Atmospheric Stellar Parameters Estimator

ZASPE (Zonal Atmospheric Stellar Parameters Estimator) computes the atmospheric stellar parameters (Teff, log(g), [Fe/H] and vsin(i)) from echelle spectra via least squares minimization with a pre-computed library of synthetic spectra. The minimization is performed only in the most sensitive spectral zones to changes in the atmospheric parameters. The uncertainities and covariances computed by ZASPE assume that the principal source of error is the systematic missmatch between the observed spectrum and the sythetic one that produces the best fit. ZASPE requires a grid of synthetic spectra and can use any pre-computed library minor modifications.

[ascl:1602.003]
ZAP: Zurich Atmosphere Purge

ZAP (Zurich Atmosphere Purge) provides sky subtraction for integral field spectroscopy; its approach is based on principal component analysis (PCA) developed for the Multi Unit Spectrographic Explorer (MUSE) integral field spectrograph. ZAP employs filtering and data segmentation to enhance the inherent capabilities of PCA for sky subtraction. ZAP reduces sky emission residuals while robustly preserving the flux and line shapes of astronomical sources; this method works in a variety of observational situations from sparse fields with a low density of sources to filled fields in which the target source fills the field of view. With the inclusion of both of these situations the method is generally applicable to many different science cases and should also be useful for other instrumentation.

[ascl:1011.022]
yt: A Multi-Code Analysis Toolkit for Astrophysical Simulation Data

yt is an open source, community-developed volumetric analysis and visualization toolkit. Originally designed for handling Enzo's (ascl:1010.072) structure adaptive mesh refinement (AMR) data, yt has been extended to work with numerous simulation methods and simulation codes including Orion, RAMSES (ascl:1011.007), and FLASH (ascl:1010.082). Analysis and visualization with yt are oriented around physically relevant quantities rather than quantities native to data representation on-disk or in-memory. yt can be used for projections, multivariate volume rendering, multi-dimensional histograms, halo finding, light cone generation and topologically-connected isocontour identification.

yt benefits from the contributions of a broad range of community members, and a full list of credits for the code can be found on the yt website or in the source repository.

[ascl:1203.010]
Youpi: YOUr processing PIpeline

Youpi is a portable, easy to use web application providing high level functionalities to perform data reduction on scientific FITS images. Built on top of various open source reduction tools released to the community by TERAPIX (http://terapix.iap.fr), Youpi can help organize data, manage processing jobs on a computer cluster in real time (using Condor) and facilitate teamwork by allowing fine-grain sharing of results and data. Youpi is modular and comes with plugins which perform, from within a browser, various processing tasks such as evaluating the quality of incoming images (using the QualityFITS software package), computing astrometric and photometric solutions (using SCAMP), resampling and co-adding FITS images (using SWarp) and extracting sources and building source catalogues from astronomical images (using SExtractor). Youpi is useful for small to medium-sized data reduction projects; it is free and is published under the GNU General Public License.

[ascl:1312.009]
YODA: Yet another Object Detection Application

YODA, implemented in C++, performs object detection, photometry and star-galaxy classification on astronomical images. Developed specifically to cope with the multi-band imaging data common in modern extragalactic imaging surveys, it is modular and therefore easily adaptable to specific needs. YODA works under conditions of inhomogeneous background noise across the detection frame, and performs accurate aperture photometry in image sets not sharing a common coordinate system or pixel scale as is often the case in present-day extragalactic survey work.

[ascl:1403.012]
YNOGKM: Time-like geodesics in the Kerr-Newmann Spacetime calculations

YNOGKM (Yun-Nan observatories geodesic in a Kerr-Newman spacetime for massive particles) performs fast calculation of time-like geodesics in the Kerr-Newman (K-N) spacetime; it is a direct extension of YNOGK (Yun-Nan observatories geodesic Kerr) calculating null geodesics in a Kerr spacetime. The four Boyer-Lindquis coordinates and proper time are expressed as functions of a parameter p semi-analytically by using the Weierstrass' and Jacobi's elliptic functions and integrals. The elliptic integrals are computed by Carlson's elliptic integral method, which guarantees the fast speed of the code. The source Fortran file ynogkm.f90 contains three modules: constants, rootfind, ellfunction, and blcoordinates.

[ascl:1305.008]
YNOGK: Calculating null geodesics in the Kerr spacetime

YNOGK, written in Fortran, calculates the null geodesics in the Kerr spacetime. It uses Weierstrass' and Jacobi's elliptic functions to express all coordinates and affine parameters as analytical and numerical functions of a parameter $p$, which is an integral value along the geodesic. The information about the turning points do not need to be specified in advance by the user, allowing applications such as imaging, the calculation of line profiles or the observer-emitter problem to become root finding problems. Elliptic integrations are computed by Carlson's elliptic integral method, which allows fast computation.

[ascl:1306.016]
Yaxx: Yet another X-ray extractor

Yaxx is a Perl script that facilitates batch data processing using Perl open source software and commonly available software such as CIAO/Sherpa, S-lang, SAS, and FTOOLS. For Chandra and XMM analysis it includes automated spectral extraction, fitting, and report generation. Yaxx can be run without climbing an extensive learning curve; even so, yaxx is highly configurable and can be customized to support complex analysis. yaxx uses template files and takes full advantage of the unique Sherpa / S-lang environment to make much of the processing user configurable. Although originally developed with an emphasis on X-ray data analysis, yaxx evolved to be a general-purpose pipeline scripting package.

[ascl:9910.008]
XSTAR: A program for calculating conditions and spectra of photoionized gases

XSTAR is a command-driven, interactive, computer program for calculating the physical conditions and emission spectra of photoionized gases. It may be applied in a wide variety of astrophysical contexts. Stripped to essentials, its job may be described simply: A spherical gas shell surrounding a central source of ionizing radiation absorbs some of this radiation and reradiates it in other portions of the spectrum; XSTAR computes the effects on the gas of absorbing this energy, and the spectrum of reradiated light. The user supplies the shape and strength of the incident continuum, the elemental abundances in the gas, its density or pressure, and its thickness; the code can be directed to return any of a large number of derived quantities, including (but not limited to) the ionization balance and temperature, opacity tables, and emitted line and continuum fluxes.

[ascl:9910.005]
XSPEC: An X-ray spectral fitting package

It has been over a decade since the first paper was published containing results determined using the general X-ray spectral-fitting program XSPEC. Since then XSPEC has become the most widely used program for this purpose, being the de facto standard for the ROSAT and the de jure standard for the ASCA and XTE satellites. Probably the most important features of XSPEC are the large number of theoretical models available and the facilities for adding new models.

[ascl:1805.016]
xspec_emcee: XSPEC-friendly interface for the emcee package

XSPEC_EMCEE is an XSPEC-friendly interface for emcee (ascl:1303.002). It carries out MCMC analyses of X-ray spectra in the X-ray spectral fitting program XSPEC (ascl:9910.005). It can run multiple xspec processes simultaneously, speeding up the analysis, and can switch to parameterizing norm

parameters in log space.

[ascl:1207.008]
xSonify: Sonification software

xSonify maps scientific data to acoustic sequences. Listening to data can help discover patterns in huge amounts of data. Written in Java, xSonify allows visually impaired people to examine numerical data for patterns. The data can be imported from local files or from remote databases via the Internet. Single results of measurements from spacecraft instruments can be selected by their corresponding variables in a specific time frame. The results are transformed into MIDI sequences which can be played with a selection of different instruments from a soundbank. Another software module enables xSonify to convert the sonified data into other sound formats to make it easier to archive and exchange the Sonification results with other scientists.

[submitted]
Xsmurf - Measuring multifractal properties with the continuous wavelet transform modulus maxima (WTMM) method

Xsmurf is a software package written in C/Tcl/Tk that implements the continuous wavelet transform modulus maxima method, an image processing tool for measuring fractal and multifractal properties in experimental and simulation data.

Multifractal analysis is described in the following page: http://www.scholarpedia.org/article/Wavelet-based_multifractal_analysis

Xsmurf has been used in multiple applications in astrophysics, e.g. :

- analysis of solar magnetograms for characterizing complexity of evolving regions

- fractal/multifractal nature and anisotropic structure of Galactic atomic hydrogen (H I)

- analysis of simulation data (velocity field, ...) of turbulent flow

[ascl:1509.001]
XSHPipelineManager: Wrapper for the VLT/X-shooter Data Reduction Pipeline

XSHPipelineManager provides a framework for reducing spectroscopic observations taken by the X-shooter spectrograph at the Very Large Telescope. This Python code wraps recipes developed by the European Southern Observatory and runs the full X-shooter data reduction pipeline. The code offers full flexibility in terms of what data reduction recipes to include and which calibration files to use. During the data reduction chain restart-files are saved, making it possible to restart at any step in the chain.

[ascl:1212.002]
XPHOT: Estimation of properties of weak X-ray sources

XPHOT is an IDL implementation of a non-parametric method for estimating the apparent and intrinsic broad-band fluxes and absorbing X-ray column densities of weak X-ray sources. XPHOT is intended for faint sources with greater than ∼5-7 counts but fewer than 100-300 counts where parametric spectral fitting methods will be superior. This method is similar to the long-standing use of color-magnitude diagrams in optical and infrared astronomy, with X-ray median energy replacing color index and X-ray source counts replacing magnitude. Though XPHOT was calibrated for thermal spectra characteristic of stars in young stellar clusters, recalibration should be possible for some other classes of faint X-ray sources such as extragalactic active galactic nuclei.

[ascl:1502.019]
XPCell: Convective plasma cells simulator

XPCell simulates convective plasma cells. The program is implemented in two versions, one using GNUPLOT and the second OpenGL. XPCell offers a GUI to introduce the parameter required by the program.

[ascl:1402.020]
XNS: Axisymmetric equilibrium configuration of neutron stars

XNS solves for the axisymmetric equilibrium configuration of neutron stars in general relativity. It can model differentially rotating and magnetic fields that are either purely toroidal, purely poloidal or in the mixed twisted torus configuration. Einsten's equations are solved using the XCFC approximation for the metric in spherical coordinates.

[ascl:1303.021]
Xmatch: GPU Enhanced Astronomic Catalog Cross-Matching

Xmatch is a cross-platform, multi-GPU tool which allows for extremely fast cross-matching between two Astronomic catalogs. It is capable of asyncronously managing multiple GPUs, ideal for workstation and cluster environments.

[ascl:1704.012]
XID+: Next generation XID development

XID+ is a prior-based source extraction tool which carries out photometry in the Herschel SPIRE (Spectral and Photometric Imaging Receiver) maps at the positions of known sources. It uses a probabilistic Bayesian framework that provides a natural framework in which to include prior information, and uses the Bayesian inference tool Stan to obtain the full posterior probability distribution on flux estimates.

[ascl:1511.004]
Xgremlin: Interferograms and spectra from Fourier transform spectrometers analysis

Xgremlin is a hardware and operating system independent version of the data analysis program Gremlin used for Fourier transform spectrometry. Xgremlin runs on PCs and workstations that use the X11 window system, including cygwin in Windows. It is used to Fourier transform interferograms, plot spectra, perform phase corrections, perform intensity and wavenumber calibration, and find and fit spectral lines. It can also be used to construct synthetic spectra, subtract continua, compare several different spectra, and eliminate ringing around lines.

[ascl:1807.031]
xGDS: Exploration Ground Data Systems

xGDS (Exploration Ground Data Systems) synthesizes real world data (from sensors, robots, ROVs, mobile devices, etc) and human observations into rich, digital maps and displays for analysis, decision making, and collaboration. xGDS processes and maps data (including video) in real-time during operations and uses it to support live role-based geolocated note taking. Notes can be used to search for and display important data. The software enables real-time analysis of data, permitting one to make inferences and plan new data collection operations while still in the field.

[ascl:1502.018]
XFGLENSES: Gravitational lens visualizer

XFGL visualizes gravitational lenses. It has an XFORM GUI and is completely interactive with the mouse. It uses OpenGL for the simulations.

[ascl:1112.013]
XEphem: Interactive Astronomical Ephemeris

XEphem is a scientific-grade interactive astronomical ephemeris package for UNIX-like systems. Written in C, X11 and Motif, it is easily ported to systems. XEphem computes heliocentric, geocentric and topocentric information for all objects and has built-in support for all planets, the moons of Mars, Jupiter, Saturn, Uranus and Earth, central meridian longitude of Mars and Jupiter, Saturn's rings, and Jupiter's Great Red Spot. It allows user-defined objects including stars, deepsky objects, asteroids, comets and Earth satellites, provides special efficient handling of large catalogs including Tycho, Hipparcos, GSC, displays data in configurable tabular formats in conjunction with several interactive graphical views, and displays a night-at-a-glance 24 hour graphic showing when any selected objects are up. It also displays 3-D stereo Solar System views that are particularly well suited for visualizing comet trajectories, quickly finds all close pairs of objects in the sky, and sorts and prints all catalogs with very flexible criteria for creating custom observing lists. Its capabilities are listed more fully in the user manual introduction.

[ascl:1107.010]
XDSPRES: CL-based package for Reducing OSIRIS Cross-dispersed Spectra

We present a description of the CL-based package XDSPRES, which aims at being a complete reducing facility for cross-dispersed spectra taken with the Ohio State Infrared Imager/Spectrometer, as installed at the SOAR telescope. This instrument provides spectra in the range between 1.2um and 2.35um in a single exposure, with resolving power of R ~ 1200. XDSPRES consists of two tasks, namely xdflat and doosiris. The former is a completely automated code for preparing normalized flat field images from raw flat field exposures. Doosiris was designed to be a complete reduction pipeline, requiring a minimum of user interaction. General steps towards a fully reduced spectrum are explained, as well as the approach adopted by our code.

[ascl:1302.016]
XDQSO: Photometic quasar probabilities and redshifts

Bovy, Jo; Hennawi, Joseph F.; Hogg, David W.; Myers, Adam D.; Kirkpatrick, Jessica A.; Schlegel, David J.; Ross, Nicholas P.; Sheldon, Erin S.; McGreer, Ian D.; Schneider, Donald P.; Weaver, Benjamin A.

XDQSO, written in IDL, calculates photometric quasar probabilities to mimick SDSS-III’s BOSS quasar target selection or photometric redshifts for quasars, whether in three redshift ranges (z < 2.2; 2.2 leq z leq 3.5; z > 3.5) or arbitrary redshift ranges.

[ascl:1708.026]
XDGMM: eXtreme Deconvolution Gaussian Mixture Modeling

XDGMM uses Gaussian mixtures to do density estimation of noisy, heterogenous, and incomplete data using extreme deconvolution (XD) algorithms which is compatible with the scikit-learn machine learning methods. It implements both the astroML and Bovy et al. (2011) algorithms, and extends the BaseEstimator class from scikit-learn so that cross-validation methods work. It allows the user to produce a conditioned model if values of some parameters are known.

[ascl:1810.016]
XCLASS: eXtended CASA Line Analysis Software Suite

XCLASS (eXtended CASA Line Analysis Software Suite) extends CASA (ascl:1107.013) with new functions for modeling interferometric and single dish data. It provides a tool for calculating synthetic spectra by solving the radiative transfer equation for an isothermal object in one dimension, taking into account the finite source size and dust attenuation. It also includes an interface for MAGIX (ascl:1303.009) to find the parameter set that most closely reproduces the data.

[ascl:1312.005]
XAssist: Automatic analysis of X-ray astrophysics data

XAssist provides automation of X-ray astrophysics, specifically data reprocessing, source detection, and preliminary spatial, temporal and spectral analysis for each source with sufficient counts, with an emphasis on galaxies. It has been used for data from Chandra, ROSAT, XMM-Newton, and other various projects.

[ascl:1601.019]
WzBinned: Binned and uncorrelated estimates of dark energy EOS extractor

WzBinned extracts binned and uncorrelated estimates of dark energy equation of state w(z) using Type Ia supernovae Hubble diagram and other cosmological probes and priors. It can handle an arbitrary number of input distance modulus data (entered as an input file SNdata.dat) and various existing cosmological information.

[ascl:1211.003]
WVT Binning: Spatially adaptive 2-D binning

WVT Binning is a spatially adaptive 2-dimensional binning algorithm designed to bin sparse X-ray data. It can handle background subtracted, exposure corrected data to produce intensity images, hardness ratio maps, or temperature maps. The algorithm is an extension of Cappellari & Copin's (2003) Voronoi binning code and uses Weighted Voronoi Tesselations (WVT) to produce a very compact binning structure with a constant S/N per bin. The bin size adjusts to the required resolution in single-pixel steps, which minimizes the scatter around the target S/N. The code is very versatile and can in principle be applied to any type of data. The user manual contains instructions on how to apply the WVT binning code to X-ray data and how to extend the algorithm to other problems.

[ascl:1207.014]
wvrgcal: Correction of atmospheric phase fluctuations in ALMA observations

wvrgcal is a command line front end to LibAIR, the atmospheric inference library for phase correction of ALMA data using water vapour radiometers, and is the user-facing application for calculating atmospheric phase correction from WVR data. wvrgcal outputs a CASA gain calibration table which can then be applied to the observed data in the usual way.

[ascl:1402.029]
wssa_utils: WSSA 12 micron dust map utilities

wssa_utils contains utilities for accessing the full-sky, high-resolution maps of the WSSA 12 micron data release. Implementations in both Python and IDL are included. The code allows users to sample values at (longitude, latitude) coordinates of interest with ease, transparently mapping coordinates to WSSA tiles and performing interpolation. The wssa_utils software also serves to define a unique WSSA 12 micron flux at every location on the sky.

[ascl:1010.071]
WSHAPE: Gravitational Softening and Adaptive Mass Resolution

Pairwise forces between particles in cosmological N-body simulations are generally softened to avoid hard collisions. Physically, this softening corresponds to treating the particles as diffuse clouds rather than point masses. For particles of unequal mass (and hence unequal softening length), computing the softened force involves a nontrivial double integral over the volumes of the two particles. We show that Plummer force softening is consistent with this interpretation of softening while spline softening is not. We provide closed-form expressions and numerical implementation for pairwise gravitational force laws for pairs of particles of general softening scales $epsilon_1$ and $epsilon_2$ assuming the commonly used cloud profiles: NGP, CIC, TSC, and PQS. Similarly, we generalize Plummer force law into pairs of particles of general softenings. We relate our expressions to the gaussian, Plummer and spline force softenings known from literature. Our expressions allow possible inclusions of pointlike particles such as stars or supermassive black holes.

[ascl:1408.023]
WSClean: Widefield interferometric imager

Offringa, A. R.; McKinley, B.; Hurley-Walker, N.; Briggs, F. H.; Wayth, R. B.; Kaplan, D. L.; Bell, M. E.; Feng, L.; Neben, A. R.; Hughes, J. D.; Rhee, J.; Murphy, T.; Bhat, N. D. R.; Bernardi, G.; Bowman, J. D.; Cappallo, R. J.; Corey, B. E.; Deshpande, A. A.; Emrich, D.; Ewall-Wice, A.; Gaensler, B. M.; Goeke, R.; Greenhill, L. J.; Hazelton, B. J.; Hindson, L.; Johnston-Hollitt, M.; Jacobs, D. C.; Kasper, J. C.; Kratzenberg, E.; Lenc, E.; Lonsdale, C. J.; Lynch, M. J.; McWhirter, S. R.; Mitchell, D. A.; Morales, M. F.; Morgan, E.; Kudryavtseva, N.; Oberoi, D.; Ord, S. M.; Pindor, B.; Procopio, P.; Prabu, T.; Riding, J.; Roshi, D. A.; Shankar, N. Udaya; Srivani, K. S.; Subrahmanyan, R.; Tingay, S. J.; Waterson, M.; Webster, R. L.; Whitney, A. R.; Williams, A.; Williams, C. L.

WSClean (w-stacking clean) is a fast generic widefield imager. It uses the w-stacking algorithm and can make use of the w-snapshot algorithm. It supports full-sky imaging and proper beam correction for homogeneous dipole arrays such as the MWA. WSClean allows Hogbom and Cotton-Schwab cleaning, and can clean polarizations joinedly. All operations are performed on the CPU; it is not specialized for GPUs.

[ascl:1304.004]
Wqed: Lightcurve Analysis Suite

Wqed (pronounced "Wicked") is a set of tools developed by the Delaware Asteroseismic Research Center (DARC) to simplify the process of reducing time-series CCD data on variable stars. It does not provide tools to measure the brightness of stars in individual frames, focusing instead on what comes next:

- - selecting and removing data lost to cloud,

- removing the effects of light cloud and seeing variations,

- keeping track of what star a given data set refers to, and when that data was taken, and

- performing barycentric corrections to data.

[ascl:1204.014]
WOMBAT: sWift Objects for Mhd BAsed on Tvd

WOMBAT (sWift Objects for Mhd BAsed on Tvd) is an astrophysical fluid code that is an implementation of a non-relativistic MHD TVD scheme; an extension for relativistic MHD has been added. The code operates on 1, 2, and 3D Eulerian meshes (cartesian and cylindrical coordinates) with magnetic field divergence restriction controlled by a constrained transport (CT) scheme. The user can tune code performance to a given processor based on chip cache sizes. Proper settings yield significant speed-ups due to efficient cache reuse.

[ascl:1212.007]
WOLF: FITS file processor

WOLF processes FITS files and generates photometry files, annotated JPGs, opacity maps, background, transient detection and luminance changes detection. This software was used to process data for the Night Sky Live project.

[ascl:1312.002]
WND-CHARM: Multi-purpose image classifier

WND-CHARM quantitatively analyzes morphologies of galaxy mergers and associate galaxies by their morphology. It computes a large set (up to ~2700) of image features for each image based on the WND-CHARM algorithm. It can then split the images into training and test sets and classify them. The software extracts the image content descriptor from raw images, image transforms, and compound image transforms. The most informative features are then selected, and the feature vector of each image is used for classification and similarity measurement using Fisher discriminant scores and a variation of Weighted Nearest Neighbor analysis. WND-CHARM's results comparable favorably to the performance of task-specific algorithms developed for tested datasets. The simple user interface allows researchers who are not knowledgeable in computer vision methods and have no background in computer programming to apply image analysis to their data.

[ascl:1204.001]
WM-basic: Modeling atmospheres of hot stars

WM-basic is an easy-to-use interface to a program package which models the atmospheres of Hot Stars (and also SN and GN). The release comprises all programs required to calculate model atmospheres which especially yield ionizing fluxes and synthetic spectra. WM-basic is a native 32-bit application, conforming to the Multiple Documents Interface (MDI) standards for Windows XP/2000/NT/9x. All components of the program package have been compiled with Digital Visual Fortran V6.6(Pro) and Microsoft Visual C++.

[ascl:1812.001]
WISP: Wenger Interferometry Software Package

WISP (Wenger Interferometry Software Package) is a radio interferometry calibration, reduction, imaging, and analysis package. WISP is a collection of Python code implemented through CASA (ascl:1107.013). Its generic and modular framework is designed to handle any continuum or spectral line radio interferometry data.

[ascl:1806.004]
WiseView: Visualizing motion and variability of faint WISE sources

WiseView renders image blinks of Wide-field Infrared Survey Explorer (WISE) coadds spanning a multi-year time baseline in a browser. The software allows for easy visual identification of motion and variability for sources far beyond the single-frame detection limit, a key threshold not surmounted by many studies. WiseView transparently gathers small image cutouts drawn from many terabytes of unWISE coadds, facilitating access to this large and unique dataset. Users need only input the coordinates of interest and can interactively tune parameters including the image stretch, colormap and blink rate. WiseView was developed in the context of the Backyard Worlds: Planet 9 citizen science project, and has enabled hundreds of brown dwarf candidate discoveries by citizen scientists and professional astronomers.

[ascl:9910.007]
WINGSPAN: A WINdows Gamma-ray SPectral Analysis program

WINGSPAN is a program written to analyze spectral data from the Burst and Transient Source Experiment (BATSE) on NASA's Compton Gamma-Ray Observatory. Data files in the FITS (BFITS) format are suitable for input into the program. WINGSPAN can be used to view and manipulate event time histories or count spectra, and also has the capability to perform spectral deconvolution via a standard forward folding model fitting technique (Levenberg-Marquardt algorithm). Although WINGSPAN provides many functions for data manipulation, the program was designed to allow users to easily plug in their own external IDL routines. These external routines have access to all data read from the FITS files, as well as selection intervals created in the main part of WINGSPAN (background intervals and model, etc).

[ascl:1010.084]
WhiskyMHD: Numerical Code for General Relativistic Magnetohydrodynamics

Whisky is a code to evolve the equations of general relativistic hydrodynamics (GRHD) and magnetohydrodynamics (GRMHD) in 3D Cartesian coordinates on a curved dynamical background. It was originally developed by and for members of the EU Network on Sources of Gravitational Radiation and is based on the Cactus Computational Toolkit. Whisky can also implement adaptive mesh refinement (AMR) if compiled together with Carpet.

Whisky has grown from earlier codes such as GR3D and GRAstro_Hydro, but has been rewritten to take advantage of some of the latest research performed here in the EU. The motivation behind Whisky is to compute gravitational radiation waveforms for systems that involve matter. Examples would include the merger of a binary system containing a neutron star, which are expected to be reasonably common in the universe and expected to produce substantial amounts of radiation. Other possible sources are given in the projects list.

[ascl:1404.013]
WFC3UV_GC: WFC3 UVIS geometric-distortion correction

WFC3UV_GC is an improved geometric-distortion solution for the Hubble Space Telescope UVIS channel of Wide Field Camera 3 for ten broad-band filters. The solution is made up of three parts:

1.) a 3rd-order polynomial to deal with the general optical distortion;

2.) a table of residuals that accounts for both chip-related anomalies and fine-structure introduced by the filter; and,

3.) a linear transformation to put the two chips into a convenient master frame.

[ascl:1705.015]
WeirdestGalaxies: Outlier Detection Algorithm on Galaxy Spectra

WeirdestGalaxies finds the weirdest galaxies in the Sloan Digital Sky Survey (SDSS) by using a basic outlier detection algorithm. It uses an unsupervised Random Forest (RF) algorithm to assign a similarity measure (or distance) between every pair of galaxy spectra in the SDSS. It then uses the distance matrix to find the galaxies that have the largest distance, on average, from the rest of the galaxies in the sample, and defined them as outliers.

[ascl:1010.069]
WeightWatcher: Code to Produce Control Maps

WeightWatcher is a program that combines weight-maps, flag-maps and polygon data in order to produce control maps which can directly be used in astronomical image-processing packages like Drizzle, SWarp or SExtractor.

[ascl:1010.042]
WeightMixer: Hybrid Cross-power Spectrum Estimation

This code, which requires HEALPix 2.x, allows you to generate power spectrum estimators from WMAP 5-year maps and generate hybrid cross- and auto- power spectrum and covariance from general foreground-cleaned maps. In addition, it allows you to simulate combined maps or combinations of maps for individual detectors and do MPI spherical transforms of arrays of maps, calculate coupling matrices etc. The code includes all of LensPix - the MPI framework used for doing spherical transforms (based on HealPix).

[ascl:1609.007]
Weighted EMPCA: Weighted Expectation Maximization Principal Component Analysis

Weighted EMPCA performs principal component analysis (PCA) on noisy datasets with missing values. Estimates of the measurement error are used to weight the input data such that the resulting eigenvectors, when compared to classic PCA, are more sensitive to the true underlying signal variations rather than being pulled by heteroskedastic measurement noise. Missing data are simply limiting cases of weight = 0. The underlying algorithm is a noise weighted expectation maximization (EM) PCA, which has additional benefits of implementation speed and flexibility for smoothing eigenvectors to reduce the noise contribution.

[ascl:1504.007]
WebbPSF: James Webb Space Telescope PSF Simulation Tool

Perrin, Marshall D.; Long, Joseph; Sivaramakrishnan, Anand; Lajoie, Charles-Phillipe; Elliot, Erin; Pueyo, Laurent; Albert, Loic

WebbPSF provides a PSF simulation tool in a flexible and easy-to-use software package implemented in Python. Functionality includes support for spectroscopic modes of JWST NIRISS, MIRI, and NIRSpec, including modeling of slit losses and diffractive line spread functions.

[ascl:1807.020]
wdmerger: Simulate white dwarf mergers with CASTRO

wdmerger simulates binary white dwarf mergers (and related events) in CASTRO (ascl:1105.010) and provides useful information on the viability of mergers of white dwarfs as a progenitor for Type Ia supernovae.

[ascl:1806.012]
WDEC: White Dwarf Evolution Code

WDEC (White Dwarf Evolution Code), written in Fortran, offers a fast and fairly easy way to produce models of white dwarfs. The code evolves hot (~100,000 K) input models down to a chosen effective temperature by relaxing the models to be solutions of the equations of stellar structure. The code can also be used to obtain g-mode oscillation modes for the models.

[ascl:1109.015]
WCSTools: Image Astrometry Toolkit

WCSTools is a package of programs and a library of utility subroutines for setting and using the world coordinate systems (WCS) in the headers of the most common astronomical image formats, FITS and IRAF .imh, to relate image pixels to sky coordinates. In addition to dealing with image WCS information, WCSTools has extensive catalog search, image header manipulation, and coordinate and time conversion tasks. This software is all written in very portable C, so it should compile and run on any computer with a C compiler.

[ascl:1108.003]
WCSLIB and PGSBOX

WCSLIB is a C library, supplied with a full set of Fortran wrappers, that implements the "World Coordinate System" (WCS) standard in FITS (Flexible Image Transport System). It also includes a PGPLOT-based routine, PGSBOX, for drawing general curvilinear coordinate graticules and a number of utility programs.

[ascl:1807.002]
Warpfield: Winds And Radiation Pressure: Feedback Induced Expansion, colLapse and Dissolution

Warpfield (Winds And Radiation Pressure: Feedback Induced Expansion, colLapse and Dissolution) calculates shell dynamics and shell structure simultaneously for isolated massive clouds (≥10^{5} M_{☉}). This semi-analytic 1D feedback model scans a large range of physical parameters (gas density, star formation efficiency, and metallicity) to estimate escape fractions of ionizing radiation f_{esc, I}, the minimum star formation efficiency ∊_{min} required to drive an outflow, and recollapse time-scales for clouds that are not destroyed by feedback.

[ascl:1710.001]
vysmaw: Fast visibility stream muncher

The vysmaw client library facilitates the development of code for processes to tap into the fast visibility stream on the National Radio Astronomy Observatory's Very Large Array correlator back-end InfiniBand network. This uses the vys protocol to allow loose coupling to clients that need to remotely access memory over an Infiniband network.

[ascl:1704.011]
VULCAN: Chemical Kinetics For Exoplanetary Atmospheres

VULCAN describes gaseous chemistry from 500 to 2500 K using a reduced C-H-O chemical network with about 300 reactions. It uses eddy diffusion to mimic atmospheric dynamics and excludes photochemistry, and can be used to examine the theoretical trends produced when the temperature-pressure profile and carbon-to-oxygen ratio are varied.

[ascl:1407.013]
VStar: Variable star data visualization and analysis tool

VStar is a multi-platform, easy-to-use variable star data visualization and analysis tool. Data for a star can be read from the AAVSO (American Association of Variable Star Observers) database or from CSV and TSV files. VStar displays light curves and phase plots, can produce a mean curve, and analyzes time-frequency with Weighted Wavelet Z-Transform. It offers tools for period analysis, filtering, and other functions.

[ascl:1811.017]
Vplanet: Virtual planet simulator

Barnes, Rory; Deitrick, Russell; Luger, Rodrigo; Driscoll, Peter; Fleming, David; Quinn, Thomas; Smotherman, Hayden; Garcia, Rodolfo; McDonald, Diego; Wilhelm, Caitlyn; Guyer, Benjamin

Vplanet simulates planetary system evolution with a focus on habitability. Physical models, typically consisting of ordinary differential equations for stellar, orbital, tidal, rotational, atmospheric, internal, magnetic, climate, and galactic evolution, are coupled together to simulate evolution for the age of a system.

[ascl:1408.016]
vpguess: Fitting multiple Voigt profiles to spectroscopic data

vpguess facilitates the fitting of multiple Voigt profiles to spectroscopic data. It is a graphical interface to VPFIT (ascl:1408.015). Originally meant to simplify the process of setting up first guesses for a subsequent fit with VPFIT, it has developed into a full interface to VPFIT. It may also be used independently of VPFIT for displaying data, playing around with data and models, "chi-by-eye" fits, displaying the result of a proper fit, pretty plots, etc. vpguess is written in C, and the graphics are based on PGPLOT (ascl:1103.002).

[ascl:1408.015]
VPFIT: Voigt profile fitting program

The VPFIT program fits multiple Voigt profiles (convolved with the instrument profiles) to spectroscopic data that is in FITS or an ASCII file. It requires CFITSIO (ascl:1010.001) and PGPLOT (ascl:1103.002); the tarball includes RDGEN (ascl:1408.017), which can be used with VPFIT to set up the fits, fit the profiles, and examine the result in interactive mode for setting up initial guesses; vpguess (ascl:1408.016) can also be used to set up an initial file.

[ascl:1309.008]
VOStat: Statistical analysis of astronomical data

VOStat allows astronomers to use both simple and sophisticated statistical routines on large datasets. This tool uses the large public-domain statistical computing package R. Datasets can be uploaded in either ASCII or VOTABLE (preferred) format. The statistical computations are performed by the VOStat and results are returned to the user.

[ascl:1205.011]
VOSpec: VO Spectral Analysis Tool

VOSpec is a multi-wavelength spectral analysis tool with access to spectra, theoretical models and atomic and molecular line databases registered in the VO. The standard tools of VOSpec include line and continuum fitting, redshift and reddening correction, spectral arithmetic and convolution between spectra, equivalent width and flux calculations, and a best fitting algorithm for fitting selected SEDs to a TSAP service. VOSpec offers several display modes (tree vs table) and organising functionalities according to the available metadata for each service, including distance from the observation position.

[ascl:1211.006]
Voronoi binning method

The Voronoi binning method is an IDL program to bin two-dimensional data to a constant signal-to-noise ratio per bin. It optimally solves the problem of preserving the maximum spatial resolution of general two-dimensional data, given a constraint on the minimum signal-to-noise ratio.

[ascl:1309.006]
VOPlot: Toolkit for Scientific Discovery using VOTables

Kale, Sonali; Vijayaraman, T. M.; Kembhavi, Ajit; Krishnan, P. R.; Navelkar, Amey, Hedge, Hrishikesh; Kulkarni, Pallavi; Balaji, K. D.

VOPlot is a tool for visualizing astronomical data. It was developed in Java and acts on data available in VOTABLE, ASCII and FITS formats. VOPlot is available as a stand alone version, which is to be installed on the user's machine, or as a web-based version fully integrated with the VizieR database.

[ascl:1309.007]
VOMegaPlot: Plotting millions of points

Urunkar, Nilesh; Kembhavi, Ajit K.; Navelkar, Ameya; Pandya, Jagruti; Moosani, Vivekananda; Nair, Prameela; Shaikh, Mohasin

VOMegaPlot, a Java based tool, has been developed for visualizing astronomical data that is available in VOTable format. It has been specifically optimized for handling large number of points (in the range of millions). It has the same look and feel as VOPlot (ascl:1309.006) and both these tools have certain common functionality.

[ascl:1811.016]
VoigtFit: Absorption line fitting for Voigt profiles

VoigtFit fits Voigt profiles to absorption lines. It fits multiple components for various atomic lines simultaneously, allowing parameters to be tied and fixed, and can automatically fit a polynomial continuum model together with the line profiles. A physical model can be used to constrain thermal and turbulent broadening of absorption lines as well as implementing molecular excitation models. The code uses a χ2 minimization approach to find the best solution and offers interactive features such as manual continuum placement locally around each line, manual masking of undesired fitting regions, and interactive definition of velocity components for various elements, improving the ease of estimating initial guesses.

[ascl:1411.003]
voevent-parse: Parse, manipulate, and generate VOEvent XML packets

voevent-parse, written in Python, parses, manipulates, and generates VOEvent XML packets; it is built atop lxml.objectify. Details of transients detected by many projects, including Fermi, Swift, and the Catalina Sky Survey, are currently made available as VOEvents, which is also the standard alert format by future facilities such as LSST and SKA. However, working with XML and adhering to the sometimes lengthy VOEvent schema can be a tricky process. voevent-parse provides convenience routines for common tasks, while allowing the user to utilise the full power of the lxml library when required. An earlier version of voevent-parse was part of the pysovo (ascl:1411.002) library.

[ascl:1304.005]
VOBOZ/ZOBOV: Halo-finding and Void-finding algorithms

VOBOZ (VOronoi BOund Zones) is an algorithm to find haloes in an N-body dark matter simulation which has little dependence on free parameters.

ZOBOV (ZOnes Bordering On Voidness) is an algorithm that finds density depressions in a set of points without any free parameters or assumptions about shape. It uses the Voronoi tessellation to estimate densities to find both voids and subvoids. It also measures probabilities that each void or subvoid arises from Poisson fluctuations.

[ascl:1701.002]
Vizic: Jupyter-based interactive visualization tool for astronomical catalogs

Vizic is a Python visualization library that builds the connection between images and catalogs through an interactive map of the sky region. The software visualizes catalog data over a custom background canvas using the shape, size and orientation of each object in the catalog and displays interactive and customizable objects in the map. Property values such as redshift and magnitude can be used to filter or apply colormaps, and objects can be selected for further analysis through standard Python functions from inside a Jupyter notebook.

Vizic allows custom overlays to be appended dynamically on top of the sky map; included are Voronoi, Delaunay, Minimum Spanning Tree and HEALPix layers, which are helpful for visualizing large-scale structure. Overlays can be generated, added or removed dynamically with one line of code. Catalog data is kept in a non-relational database. The Jupyter Notebook allows the user to create scripts to analyze and plot the data selected/displayed in the interactive map, making Vizic a powerful and flexible interactive analysis tool. Vizic be used for data inspection, clustering analysis, galaxy alignment studies, outlier identification or simply large-scale visualizations.

[ascl:1402.001]
Vissage: ALMA VO Desktop Viewer

Vissage (VISualisation Software for Astronomical Gigantic data cubEs) is a FITS browser primarily targeting FITS data cubes obtained from ALMA. Vissage offers basic functionality for viewing three-dimensional data cubes, integrated intensity map, flipbook, channel map, and P-V diagram. It has several color sets and color scales available, offers panning and zooming, and can connect with the ALMA WebQL system and the JVO Subaru Image Cutout Service.

[ascl:1011.020]
VisIVO: Integrated Tools and Services for Large-Scale Astrophysical Visualization

Becciani, U.; Costa, A.; Antonuccio-Delogu, V.; Caniglia, G.; Comparato, M.; Gheller, C.; Jin, Z.; Krokos, M.; Massimino, P.

VisIVO is an integrated suite of tools and services specifically designed for the Virtual Observatory. This suite constitutes a software framework for effective visual discovery in currently available (and next-generation) very large-scale astrophysical datasets. VisIVO consists of VisiVO Desktop - a stand alone application for interactive visualization on standard PCs, VisIVO Server - a grid-enabled platform for high performance visualization and VisIVO Web - a custom designed web portal supporting services based on the VisIVO Server functionality. The main characteristic of VisIVO is support for high-performance, multidimensional visualization of very large-scale astrophysical datasets. Users can obtain meaningful visualizations rapidly while preserving full and intuitive control of the relevant visualization parameters. This paper focuses on newly developed integrated tools in VisIVO Server allowing intuitive visual discovery with 3D views being created from data tables. VisIVO Server can be installed easily on any web server with a database repository. We discuss briefly aspects of our implementation of VisiVO Server on a computational grid and also outline the functionality of the services offered by VisIVO Web. Finally we conclude with a summary of our work and pointers to future developments.

[ascl:1103.007]
VisIt: Interactive Parallel Visualization and Graphical Analysis Tool

VisIt is a free interactive parallel visualization and graphical analysis tool for viewing scientific data on Unix and PC platforms. Users can quickly generate visualizations from their data, animate them through time, manipulate them, and save the resulting images for presentations. VisIt contains a rich set of visualization features so that you can view your data in a variety of ways. It can be used to visualize scalar and vector fields defined on two- and three-dimensional (2D and 3D) structured and unstructured meshes. VisIt was designed to handle very large data set sizes in the terascale range and yet can also handle small data sets in the kilobyte range. See the table below for more details about the tool’s features.

VisIt was developed by the Department of Energy (DOE) Advanced Simulation and Computing Initiative (ASCI) to visualize and analyze the results of terascale simulations. It was developed as a framework for adding custom capabilities and rapidly deploying new visualization technologies. Although the primary driving force behind the development of VisIt was for visualizing terascale data, it is also well suited for visualizing data from typical simulations on desktop systems.

[ascl:1408.010]
VisiOmatic: Celestial image viewer

VisiOmatic is a web client for IIPImage (ascl:1408.009) and is used to visualize and navigate through large science images from remote locations. It requires STIFF (ascl:1110.006), is based on the Leaflet Javascript library, and works on both touch-based and mouse-based devices.

[ascl:1802.006]
VISIBLE: VISIbility Based Line Extraction

Loomis, Ryan A.; Oberg, Karin I.; Andrews, Sean M.; Walsh, Catherine; Czekala, Ian; Huang, Jane; Rosenfeld, Katherine A.

VISIBLE applies approximated matched filters to interferometric data, allowing line detection directly in visibility space. The filter can be created from a FITS image or RADMC3D output image, and the weak line data can be a CASA MS or uvfits file. The filter response spectrum can be output either to a .npy file or returned back to the user for scripting.

[ascl:1804.019]
ViSBARD: Visual System for Browsing, Analysis and Retrieval of Data

Roberts, D. Aaron; Boller, Ryan; Rezapkin, V.; Coleman, J.; McGuire, R.; Goldstein, M.; Kalb, V.; Kulkarni, R.; Luckyanova, M.; Byrnes, J.; Kerbel, U.; Candey, R.; Holmes, C.; Chimiak, R.; Harris, B.

ViSBARD interactively visualizes and analyzes space physics data. It provides an interactive integrated 3-D and 2-D environment to determine correlations between measurements across many spacecraft. It supports a variety of spacecraft data products and MHD models and is easily extensible to others. ViSBARD provides a way of visualizing multiple vector and scalar quantities as measured by many spacecraft at once. The data are displayed three-dimesionally along the orbits which may be displayed either as connected lines or as points. The data display allows the rapid determination of vector configurations, correlations between many measurements at multiple points, and global relationships. With the addition of magnetohydrodynamic (MHD) model data, this environment can also be used to validate simulation results with observed data, use simulated data to provide a global context for sparse observed data, and apply feature detection techniques to the simulated data.

[ascl:1204.012]
VirGO: A Visual Browser for the ESO Science Archive Facility

VirGO is the next generation Visual Browser for the ESO Science Archive Facility developed by the Virtual Observatory (VO) Systems Department. It is a plug-in for the popular open source software Stellarium adding capabilities for browsing professional astronomical data. VirGO gives astronomers the possibility to easily discover and select data from millions of observations in a new visual and intuitive way. Its main feature is to perform real-time access and graphical display of a large number of observations by showing instrumental footprints and image previews, and to allow their selection and filtering for subsequent download from the ESO SAF web interface. It also allows the loading of external FITS files or VOTables, the superimposition of Digitized Sky Survey (DSS) background images, and the visualization of the sky in a `real life' mode as seen from the main ESO sites. All data interfaces are based on Virtual Observatory standards which allow access to images and spectra from external data centers, and interaction with the ESO SAF web interface or any other VO applications supporting the PLASTIC messaging system.

[ascl:1603.003]
VIP: Vortex Image Processing pipeline for high-contrast direct imaging of exoplanets

Gomez Gonzalez, Carlos Alberto; Wertz, Olivier; Christiaens, Valentin; Absil, Olivier; Mawet, Dimitri

VIP (Vortex Image Processing pipeline) provides pre- and post-processing algorithms for high-contrast direct imaging of exoplanets. Written in Python, VIP provides a very flexible framework for data exploration and image processing and supports high-contrast imaging observational techniques, including angular, reference-star and multi-spectral differential imaging. Several post-processing algorithms for PSF subtraction based on principal component analysis are available as well as the LLSG (Local Low-rank plus Sparse plus Gaussian-noise decomposition) algorithm for angular differential imaging. VIP also implements the negative fake companion technique coupled with MCMC sampling for rigorous estimation of the flux and position of potential companions.

[ascl:1010.058]
VINE: A numerical code for simulating astrophysical systems using particles

VINE is a particle based astrophysical simulation code. It uses a tree structure to efficiently solve the gravitational N-body problem and Smoothed Particle Hydrodynamics (SPH) to simulate gas dynamical effects. The code has been successfully used for a number of studies on galaxy interactions, galactic dynamics, star formation and planet formation and given the implemented physics, other applications are possible as well.

[ascl:1201.006]
VIM: Visual Integration and Mining

VIM (Virtual Observatory Integration and Mining) is a data retrieval and exploration application that assumes an astronomer has a list of 'sources' (positions in the sky), and wants to explore archival catalogs, images, and spectra of the sources, in order to identify, select, and mine the list. VIM does this either through web forms, building a custom 'data matrix,' or locally through downloadable Python code. Any VO-registered catalog service can be used by VIM, as well as co-registered image cutouts from VO-image services, and spectra from VO-spectrum services. The user could, for example, show together: proper motions from GSC2, name and spectral type from NED, magnitudes and colors from 2MASS, and cutouts and spectra from SDSS. VIM can compute columns across surveys and sort on these (eg. 2MASS J magnitude minus SDSS g). For larger sets of sources, VIM utilizes the asynchronous Nesssi services from NVO, that can run thousands of cone and image services overnight.

[ascl:1403.016]
Viewpoints: Fast interactive linked plotting of large multivariate data sets

Viewpoints is an interactive tool for exploratory visual analysis of large high-dimensional (multivariate) data. It uses linked scatterplots to find relations in a few seconds that can take much longer with other plotting tools. Its features include linked scatter plots with brushing, dynamic histograms, normalization, and outlier detection/removal.

[ascl:1407.014]
VIDE: The Void IDentification and Examination toolkit

Sutter, P. M.; Lavaux, Guilhem; Hamaus, Nico; Pisani, Alice; Wandelt, Benjamin D.; Warren, Michael S.; Villaescusa-Navarro, Francisco; Zivick, Paul; Mao, Qingqing; Thompson, Benjamin B.

The Void IDentification and Examination toolkit (VIDE) identifies voids using a modified version of the parameter-free void finder ZOBOV (ascl:1304.005); a Voronoi tessellation of the tracer particles is used to estimate the density field followed by a watershed algorithm to group Voronoi cells into zones and subsequently voids. Output is a summary of void properties in plain ASCII; a Python API is provided for analysis tasks, including loading and manipulating void catalogs and particle members, filtering, plotting, computing clustering statistics, stacking, comparing catalogs, and fitting density profiles.

[ascl:1404.010]
VictoriaReginaModels: Stellar evolutionary tracks

The Victoria–Regina stellar models are comprised of seventy-two grids of stellar evolutionary tracks accompanied by complementary zero-age horizontal branches and are presented in “equivalent evolutionary phase” (.eep) files. This Fortran 77 software interpolates isochrones, isochrone population functions, luminosity functions, and color functions of stellar evolutionary tracks.

[ascl:1306.015]
VHD: Viscous pseudo-Newtonian accretion

VHD is a numerical study of viscous fluid accretion onto a black hole. The flow is axisymmetric and uses a pseudo-Newtonian potential to model relativistic effects near the event horizon. VHD is based on ZEUS-2D (Stone & Norman 1992) with the addition of an explicit scheme for the viscosity.

[ascl:1204.007]
VH-1: Multidimensional ideal compressible hydrodynamics code

VH-1 is a multidimensional ideal compressible hydrodynamics code written in FORTRAN for use on any computing platform, from desktop workstations to supercomputers. It uses a Lagrangian remap version of the Piecewise Parabolic Method developed by Paul Woodward and Phil Colella in their 1984 paper. VH-1 comes in a variety of versions, from a simple one-dimensional serial variant to a multi-dimensional version scalable to thousands of processors.

[ascl:1904.019]
Vevacious: Global minima of one-loop effective potentials generator

Vevacious takes a generic expression for a one-loop effective potential energy function and finds all the tree-level extrema, which are then used as the starting points for gradient-based minimization of the one-loop effective potential. The tunneling time from a given input vacuum to the deepest minimum, if different from the input vacuum, can be calculated. The parameter points are given as files in the SLHA format (though is not restricted to supersymmetric models), and new model files can be easily generated automatically by the Mathematica package SARAH (ascl:1904.020).

[ascl:1503.011]
VESPA: False positive probabilities calculator

Validation of Exoplanet Signals using a Probabilistic Algorithm (VESPA) calculates false positive probabilities and statistically validates transiting exoplanets. Written in Python, it uses isochrones [ascl:1503.010] and the package simpledist.

[ascl:1802.005]
Verne: Earth-stopping effect for heavy dark matter

Verne calculates the Earth-stopping effect for super-heavy Dark Matter (DM). The code allows you to calculate the speed distribution (and DM signal rate) at an arbitrary detector location on the Earth. The calculation takes into account the full anisotropic DM velocity distribution and the full velocity dependence of the DM-nucleus cross section. Results can be obtained for any DM mass and cross section, though the results are most reliable for very heavy DM particles.

[ascl:1802.002]
venice: Mask utility

venice reads a mask file (DS9 or fits type) and a catalogue of objects (ascii or fits type) to create a pixelized mask, find objects inside/outside a mask, or generate a random catalogue of objects inside/outside a mask. The program reads the mask file and checks if a point, giving its coordinates, is inside or outside the mask, *i.e.* inside or outside at least one polygon of the mask.

[ascl:1010.021]
velfit: A Code for Modeling Non-Circular Flows in Disk Galaxies

High-quality velocity maps of galaxies frequently exhibit signatures of non-circular streaming motions. velfit yields results that are more easily interpreted than the commonly used procedure. It can estimate the magnitudes of forced non-circular motions over a broad range of bar strengths from a strongly barred galaxy, through cases of mild bar-like distortions to placing bounds on the shapes of halos in galaxies having extended rotation curves.

This code is no longer maintained and has been superseded by DiskFit (ascl:1209.011).

[ascl:1610.009]
velbin: radial velocity corrected for binary orbital motions

Velbin convolves the radial velocity offsets due to binary orbital motions with a Gaussian to model an observed velocity distribution. This can be used to measure the mean velocity and velocity dispersion from an observed radial velocity distribution, corrected for binary orbital motions. Velbin fits single- or multi-epoch data with any arbitrary binary orbital parameter distribution (as long as it can be sampled properly), however it always assumes that the intrinsic velocity distribution (i.e. corrected for binary orbital motions) is a Gaussian. Velbin samples (and edits) a binary orbital parameter distribution, fits an observed radial velocity distribution, and creates a mock radial velocity distribution that can be used to provide the fitted radial velocities in the single_epoch or multi_epoch methods.

[ascl:1809.004]
VBBINARYLENSING: Microlensing light-curve computation

Bozza, Valerio; Bachelet, Etienne; Bartolić, Fran; Heintz, Tyler M.; Hoag, Ava R.; Hundertmark, Markus

VBBinaryLensing forward models gravitational microlensing events using the advanced contour integration method; it supports single and binary lenses. The lens map is inverted on a collection of points on the source boundary to obtain a corresponding collection of points on the boundaries of the images from which the area of the images can be recovered by use of Green’s theorem. The code takes advantage of a number of techniques to make contour integration much more efficient, including using a parabolic correction to increase the accuracy of the summation, introducing an error estimate on each arc of the boundary to enable defining an optimal sampling, and allowing the inclusion of limb darkening. The code is written as a C++ library and wrapped as a Python package, and can be called from either C++ or Python.

[ascl:1704.005]
VaST: Variability Search Toolkit

VaST (Variability Search Toolkit) finds variable objects on a series of astronomical images in FITS format. The software performs object detection and aperture photometry using SExtractor (ascl:1010.064) on each image, cross-matches lists of detected stars, performs magnitude calibration with respect to the first (reference) image and constructs a lightcurve for each object. The sigma-magnitude, Stetson's L variability index, Robust Median Statistic (RoMS) and other plots may be used to visually identify variable star candidates. The two distinguishing features of VaST are its ability to perform accurate aperture photometry of images obtained with non-linear detectors and to handle complex image distortions. VaST can be used in cases of unstable PSF (e.g., bad guiding or with digitized wide-field photographic images), and has been successfully applied to images obtained with telescopes ranging from 0.08 to 2.5m in diameter equipped with a variety of detectors including CCD, CMOS, MIC and photographic plates.

[ascl:1208.016]
VARTOOLS: Light Curve Analysis Program

The VARTOOLS program is a command line utility that provides tools for analyzing time series astronomical data. It implements a number of routines for calculating variability/periodicity statistics of light curves, as well as tools for modifying and filtering light curves.

[ascl:1111.012]
VAPOR: Visualization and Analysis Platform for Ocean, Atmosphere, and Solar Researchers

VAPOR is the Visualization and Analysis Platform for Ocean, Atmosphere, and Solar Researchers. VAPOR provides an interactive 3D visualization environment that runs on most UNIX and Windows systems equipped with modern 3D graphics cards. VAPOR provides:

- A visual data discovery environment tailored towards the specialized needs of the astro and geosciences CFD community
- A desktop solution capable of handling terascale size data sets
- Advanced interactive 3D visualization tightly coupled with quantitative data analysis
- Support for multi-variate, time-varying data
- Close coupling with RSI's powerful interpretive data language, IDL
- Support for 3D visualization of WRF-ARW datasets

[ascl:1506.010]
VAPID: Voigt Absorption-Profile [Interstellar] Dabbler

VAPID (Voigt Absorption Profile [Interstellar] Dabbler) models interstellar absorption lines. It predicts profiles and optimizes model parameters by least-squares fitting to observed spectra. VAPID allows cloud parameters to be optimized with respect to several different data set simultaneously; those data sets may include observations of different transitions of a given species, and may have different S/N ratios and resolutions.

[ascl:1309.002]
VAPHOT: Precision differential aperture photometry package

VAPHOT is an aperture photometry package for precise time−series photometry of uncrowded fields, geared towards the extraction of target lightcurves of eclipsing or transiting systems. Its photometric main routine works within the IRAF (ascl:9911.002) environment and is built upon the standard aperture photometry task 'phot' from IRAF, using optimized aperture sizes. The associated analysis program 'VANALIZ' works in the IDL environment. It performs differential photometry with graphical and numerical output. VANALIZ produces plots indicative of photometric stability and permits the interactive evaluation and weighting of comparison stars. Also possible is the automatic or manual suppression of data-points and the output of statistical analyses. Several methods for the calculation of the reference brightness are offered. Specific routines for the analysis of transit 'on'-'off' photometry, comparing the target brightness inside against outside a transit are also available.

[ascl:1702.004]
Validation: Codes to compare simulation data to various observations

Validation provides codes to compare several observations to simulated data with stellar mass and star formation rate, simulated data stellar mass function with observed stellar mass function from PRIMUS or SDSS-GALEX in several redshift bins from 0.01-1.0, and simulated data B band luminosity function with observed stellar mass function, and to create plots for various attributes, including stellar mass functions, and stellar mass to halo mass. These codes can model predictions (in some cases alongside observational data) to test other mock catalogs.

[ascl:1810.004]
VaeX: Visualization and eXploration of Out-of-Core DataFrames

VaeX (Visualization and eXploration) interactively visualizes and explores big tabular datasets. It can calculate statistics such as mean, sum, count, and standard deviation on an N-dimensional grid up to a billion (10^{9}) objects/rows per second. Visualization is done using histograms, density plots, and 3d volume rendering, allowing interactive exploration of big data. VaeX uses memory mapping, zero memory copy policy and lazy computations for best performance, and integrates well with the Jupyter/IPython notebook/lab ecosystem.

[ascl:1406.009]
VADER: Viscous Accretion Disk Evolution Resource

VADER is a flexible, general code that simulates the time evolution of thin axisymmetric accretion disks in time-steady potentials. VADER handles arbitrary viscosities, equations of state, boundary conditions, and source and sink terms for both mass and energy.

[ascl:1207.003]
VAC: Versatile Advection Code

The Versatile Advection Code (VAC) is a freely available general hydrodynamic and magnetohydrodynamic simulation software that works in 1, 2 or 3 dimensions on Cartesian and logically Cartesian grids. VAC runs on any Unix/Linux system with a Fortran 90 (or 77) compiler and Perl interpreter. VAC can run on parallel machines using either the Message Passing Interface (MPI) library or a High Performance Fortran (HPF) compiler.

[ascl:1410.004]
UVOTPY: Swift UVOT grism data reduction

The two Swift UVOT grisms provide uv (170.0-500.0 nm) and visible (285.0-660.0 nm) spectra with a resolution of R~100 and 75. To reduce the grism data, UVOTPY extracts a spectrum given source sky position, and outputs a flux calibrated spectrum. UVOTPY is a replacement for the UVOTIMGRISM FTOOL (ascl:9912.002) in the HEADAS Swift package. Its extraction uses a curved aperture for the uv spectra, accounts the coincidence losses in the detector, provides more accurate anchor positions for the wavelength scale, and is valid for the whole detector.

[ascl:1402.017]
UVMULTIFIT: Fitting astronomical radio interferometric data

UVMULTIFIT, written in Python, is a versatile library for fitting models directly to visibility data. These models can depend on frequency and fitting parameters in an arbitrary algebraic way. The results from the fit to the visibilities of sources with sizes smaller than the diffraction limit of the interferometer are superior to the output obtained from a mere analysis of the deconvolved images. Though UVMULTIFIT is based on the CASA package, it can be easily adapted to other analysis packages that have a Python API.

[ascl:1606.006]
uvmcmcfit: Parametric models to interferometric data fitter

Uvmcmcfit fits parametric models to interferometric data. It is ideally suited to extract the maximum amount of information from marginally resolved observations with interferometers like the Atacama Large Millimeter Array (ALMA), Submillimeter Array (SMA), and Plateau de Bure Interferometer (PdBI). uvmcmcfit uses emcee (ascl:1303.002) to do Markov Chain Monte Carlo (MCMC) and can measure the goodness of fit from visibilities rather than deconvolved images, an advantage when there is strong gravitational lensing and in other situations. uvmcmcfit includes a pure-Python adaptation of Miriad’s (ascl:1106.007) uvmodel task to generate simulated visibilities given observed visibilities and a model image and a simple ray-tracing routine that allows it to account for both strongly lensed systems (where multiple images of the lensed galaxy are detected) and weakly lensed systems (where only a single image of the lensed galaxy is detected).

[ascl:1412.003]
UTM: Universal Transit Modeller

The Universal Transit Modeller (UTM) is a light-curve simulator for all kinds of transiting or eclipsing configurations between arbitrary numbers of several types of objects, which may be stars, planets, planetary moons, and planetary rings. A separate fitting program, UFIT (Universal Fitter) is part of the UTM distribution and may be used to derive best fits to light-curves for any set of continuously variable parameters. UTM/UFIT is written in IDL code and its source is released in the public domain under the GNU General Public License.

[ascl:1411.012]
util_2comp: Planck-based two-component dust model utilities

The util_2comp software utilities generate predictions of far-infrared Galactic dust emission and reddening based on a two-component dust emission model fit to Planck HFI, DIRBE and IRAS data from 100 GHz to 3000 GHz. These predictions and the associated dust temperature map have angular resolution of 6.1 arcminutes and are available over the entire sky. Implementations in IDL and Python are included.

[ascl:1412.009]
URCHIN: Reverse ray tracer

URCHIN is a Smoothed Particle Hydrodynamics (SPH) reverse ray tracer (i.e. from particles to sources). It calculates the amount of shielding from a uniform background that each particle experiences. Preservation of the adaptive density field resolution present in many gas dynamics codes and uniform sampling of gas resolution elements with rays are two of the benefits of URCHIN; it also offers preservation of Galilean invariance, high spectral resolution, and preservation of the standard uniform UV background in optically thin gas.

[ascl:1512.019]
UPSILoN: AUtomated Classification of Periodic Variable Stars using MachIne LearNing

UPSILoN (AUtomated Classification of Periodic Variable Stars using MachIne LearNing) classifies periodic variable stars such as Delta Scuti stars, RR Lyraes, Cepheids, Type II Cepheids, eclipsing binaries, and long-period variables (i.e. superclasses), and their subclasses (e.g. RR Lyrae ab, c, d, and e types) using well-sampled light curves from any astronomical time-series surveys in optical bands regardless of their survey-specific characteristics such as color, magnitude, and sampling rate. UPSILoN consists of two parts, one which extracts variability features from a light curve, and another which classifies a light curve, and returns extracted features, a predicted class, and a class probability. In principle, UPSILoN can classify any light curves having arbitrary number of data points, but using light curves with more than ~80 data points provides the best classification quality.

[ascl:1504.001]
UPMASK: Unsupervised Photometric Membership Assignment in Stellar Clusters

UPMASK, written in R, performs membership assignment in stellar clusters. It uses photometry and spatial positions, but can take into account other types of data. UPMASK takes into account arbitrary error models; the code is unsupervised, data-driven, physical-model-free and relies on as few assumptions as possible. The approach followed for membership assessment is based on an iterative process, principal component analysis, a clustering algorithm and a kernel density estimation.

[ascl:1901.004]
unwise_psf: PSF models for unWISE coadds

The unwise_psf Python module renders point spread function (PSF) models appropriate for use in modeling of unWISE coadd images. unwise_psf translates highly detailed single-exposure WISE PSF models in detector coordinates to the corresponding pixelized PSF models in coadd space, accounting for subtleties including the WISE scan direction and its considerable variation near the ecliptic poles. Applications of the unwise_psf module include performing forced photometry on unWISE coadds, constructing WISE-selected source catalogs based on unWISE coadds and masking unWISE coadd regions contaminated by bright stars.

[ascl:1110.021]
Univiewer: Visualisation Program for HEALPix Maps

Univiewer is a visualisation program for HEALPix maps. It is written in C++ and uses OpenGL and the wxWidgets library for cross-platform portability. Using it you can:

- Rotate and zoom maps on the sphere in 3D;
- Create high-resolution views of square patches of the map;
- Change maximum and minimum values of the colourmap interactively;
- Calculate the power spectrum of the full-sky map or a patch;
- Display any column of a HEALPix map FITS file on the sphere.

In the 3D view, a HEALPix map is projected onto a ECP pixelation to create a texture which is wrapped around the sphere. In calculating the power spectrum, the spherical harmonic transforms are computed using the same ECP pixelation. This inevitably leads to some discrepancies at small scales due to repixelation effects, but they are reasonably small.

[ascl:1503.007]
UniPOPS: Unified data reduction suite

Maddalena, Ronald J.; Garwood, Robert W.; Salter, Christopher J.; Stobie, Elizabeth B; Cram, Thomas R.; Morgan, Lorrie; Vance, Bob; Hudson, Jerome

UniPOPS, a suite of programs and utilities developed at the National Radio Astronomy Observatory (NRAO), reduced data from the observatory's single-dish telescopes: the Tucson 12-m, the Green Bank 140-ft, and archived data from the Green Bank 300-ft. The primary reduction programs, 'line' (for spectral-line reduction) and 'condar' (for continuum reduction), used the People-Oriented Parsing Service (POPS) as the command line interpreter. UniPOPS unified previous analysis packages and provided new capabilities; development of UniPOPS continued within the NRAO until 2004 when the 12-m was turned over to the Arizona Radio Observatory (ARO). The submitted code is version 3.5 from 2004, the last supported by the NRAO.

[ascl:1403.007]
Unified EOS for neutron stars

The equation of state (EOS) of dense matter is a crucial input for the neutron-star structure calculations. This Fortran code can obtain a "unified EOS" in the many-body calculations based on a single effective nuclear Hamiltonian, and is valid in all regions of the neutron star interior. For unified EOSs, the transitions between the outer crust and the inner crust and between the inner crust and the core are obtained as a result of many-body calculations.

[ascl:1804.022]
UniDAM: Unified tool to estimate Distances, Ages, and Masses

UniDAM obtains a homogenized set of stellar parameters from spectrophotometric data of different surveys. Parallax and extinction data can be incorporated into the isochrone fitting method used in UniDAM to reduce distance and age estimate uncertainties for TGAS stars for distances up to 1 kpc and decrease distance Gaia end-of-mission parallax uncertainties by about a factor of 20 and age uncertainties by a factor of two for stars up to 10 kpc away from the Sun.

[ascl:1104.007]
ULySS: A Full Spectrum Fitting Package

ULySS (University of Lyon Spectroscopic Analysis Software) is an open-source software package written in the GDL/IDL language to analyze astronomical data. ULySS fits a spectrum with a linear combination of non-linear components convolved with a line-of-sight velocity distribution (LOSVD) and multiplied by a polynomial continuum. ULySS is used to study stellar populations of galaxies and star clusters and atmospheric parameters of stars.

[ascl:1611.001]
UltraNest: Pythonic Nested Sampling Development Framework and UltraNest

This three-component package provides a Pythonic implementation of the Nested Sampling integration algorithm for Bayesian model comparison and parameter estimation. It offers multiple implementations for constrained drawing functions and a test suite to evaluate the correctness, accuracy and efficiency of various implementations. The three components are:

- a modular framework for nested sampling algorithms (nested_sampling) and their development;
- a test framework to evaluate the performance and accuracy of algorithms (testsuite); and
- UltraNest, a fast C implementation of a mixed RadFriends/MCMC nested sampling algorithm.

[ascl:1704.002]
UDAT: A multi-purpose data analysis tool

UDAT is a pattern recognition tool for mass analysis of various types of data, including image and audio. Based on its WND-CHARM (ascl:1312.002) prototype, UDAT computed a large set of numerical content descriptors from each file it analyzes, and selects the most informative features using statistical analysis. The tool can perform automatic classification of galaxy images by training with annotated galaxy images. It also has unsupervised learning capabilities, such as query-by-example of galaxies based on morphology. That is, given an input galaxy image of interest, the tool can search through a large database of images to retrieve the galaxies that are the most similar to the query image. The downside of the tool is its computational complexity, which in most cases will require a small or medium cluster.

[ascl:1303.004]
UCL_PDR: Time dependent photon-dissociation regions model

UCL_PDR is a time dependent photon-dissociation regions model that calculates self consistently the thermal balance. It can be used with gas phase only species as well as with surface species. It is very modular, has the possibility of accounting for density and pressure gradients and can be coupled with UCL_CHEM as well as with SMMOL. It has been used to model small scale (e.g. knots in proto-planetary nebulae) to large scale regions (high redshift galaxies).

[ascl:1303.006]
UCL_CHEM: time and depth dependent gas-grain chemical model

UCL_CHEM is a time and depth dependent gas-grain chemical model that can be used to estimate the fractional abundances (with respect to hydrogen) of gas and surface species in every environment where molecules are present. The model includes both gas and surface reactions. The code starts from the most diffuse state where all the gas is in atomic form and evolve sthe gas to its final density. Depending on the temperature, atoms and molecules from the gas freeze on to the grains and they hydrogenate where possible. The advantage of this approach is that the ice composition is not assumed but it is derived by a time-dependent computation of the chemical evolution of the gas-dust interaction process. The code is very modular, has been used to model a variety of regions and can be coupled with the UCL_PDR and SMMOL codes.

[ascl:1303.008]
TYCHO: Stellar evolution code

TYCHO is a general, one dimensional (spherically symmetric) stellar evolution code written in structured Fortran 77; it is designed for hydrostatic and hydrodynamic stages including mass loss, accretion, pulsations and explosions. Mixing and convection algorithms are based on 3D time-dependent simulations. It offers extensive on-line graphics using Tim Pearson's PGPLOT with X-windows and runs effectively on Linux and Mac OS X laptop and desktop computers.

NOTE: This code is no longer being supported.

[ascl:1210.025]
TwoDSSM: Self-gravitating 2D shearing sheet

TwoDSSM solves the equations of self-gravitating hydrodynamics in the shearing sheet, with cooling. TwoDSSM is configured to use a simple, exponential cooling model, although it contains code for a more complicated (and perhaps more realistic) cooling model based on a one-zone vertical model. The complicated cooling model can be switched on using a flag.

[ascl:1407.002]
TWODSPEC: Long-slit and optical fiber array spectra extensions for FIGARO

TWODSPEC offers programs for the reduction and analysis of long-slit and optical fiber array spectra, implemented as extensions to the FIGARO package (ascl:1203.013). The software are currently distributed as part of the Starlink software collection (ascl:1110.012). These programs are designed to do as much as possible for the user, to assist quick reduction and analysis of data; for example, LONGSLIT can fit multiple Gaussians to line profiles in batch and decides how many components to fit.

[ascl:1708.015]
TWO-POP-PY: Two-population dust evolution model

TWO-POP-PY runs a two-population dust evolution model that follows the upper end of the dust size distribution and the evolution of the dust surface density profile and treats dust surface density, maximum particle size, small and large grain velocity, and fragmentation. It derives profiles that describe the dust-to-gas ratios and the dust surface density profiles well in protoplanetary disks, in addition to the radial flux by solid material rain out.

[ascl:1304.015]
TVD: Total Variation Diminishing code

TVD solves the magnetohydrodynamic (MHD) equations by updating the fluid variables along each direction using the flux-conservative, second-order, total variation diminishing (TVD), upwind scheme of Jin & Xin. The magnetic field is updated separately in two-dimensional advection-constraint steps. The electromotive force (EMF) is computed in the advection step using the TVD scheme, and this same EMF is used immediately in the constraint step in order to preserve ∇˙B=0 without the need to store intermediate fluxes. The code is extended to three dimensions using operator splitting, and Runge-Kutta is used to get second-order accuracy in time. TVD offers high-resolution per grid cell, second-order accuracy in space and time, and enforcement of the ∇˙B=0 constraint to machine precision. Written in Fortran, It has no memory overhead and is fast. It is also available in a fully scalable message-passing parallel MPI implementation.

[ascl:1205.004]
Turbospectrum: Code for spectral synthesis

Turbospectrum is a 1D LTE spectrum synthesis code which covers 600 molecules, is fast with many lines, and uses the treatment of line broadening described by Barklem & O’Mara (1998).

[ascl:1906.006]
turboSETI: Python-based SETI search algorithm

TurboSETI analyzes filterbank data (frequency vs. time) for narrow band drifting signals; its main purpose is to search for signals of extraterrestrial origin. TurboSETI can search the data for hundreds of drift rates (in Hz/sec) and handles either .fil or .h5 file formats. It has several dependencies, including Blimpy (ascl:1906.002) and Astropy (ascl:1304.002).

[ascl:1011.011]
turboGL: Accurate Modeling of Weak Lensing

turboGL is a fast Mathematica code based on a stochastic approach to cumulative weak lensing. It can easily compute the lensing PDF relative to arbitrary halo mass distributions, selection biases, number of observations, halo profiles and evolutions, making it a useful tool to study how lensing depends on cosmological parameters and impact on observations.

[ascl:1604.012]
TTVFaster: First order eccentricity transit timing variations (TTVs)

TTVFaster implements analytic formulae for transit time variations (TTVs) that are accurate to first order in the planet–star mass ratios and in the orbital eccentricities; the implementations are available in several languages, including IDL, Julia, Python and C. These formulae compare well with more computationally expensive N-body integrations in the low-eccentricity, low mass-ratio regime when applied to simulated and to actual multi-transiting Kepler planet systems.

[ascl:1404.015]
TTVFast: Transit timing inversion

TTVFast efficiently calculates transit times for n-planet systems and the corresponding radial velocities. The code uses a symplectic integrator with a Keplerian interpolator for the calculation of transit times (Nesvorny et al. 2013); it is available in both C and Fortran.

[ascl:1409.002]
Tsyganenko Geomagnetic Field Models

The Tsyganenko models are semi-empirical best-fit representations for the magnetic field, based on a large number of satellite observations (IMP, HEOS, ISEE, POLAR, Geotail, GOES, etc). The models include the contributions from major external magnetospheric sources: ring current, magnetotail current system, magnetopause currents, and large-scale system of field-aligned currents.

[ascl:1406.011]
TSP: Time-Series/Polarimetry Package

TSP is an astronomical data reduction package that handles time series data and polarimetric data from a variety of different instruments, and is distributed as part of the Starlink software collection (ascl:1110.012).

[ascl:1509.005]
TRUVOT: True Background Technique for the Swift UVOT Grisms

TRUVOT decontaminates Swift UVOT grism spectra for transient objects. The technique makes use of template images in a process similar to image subtraction.

[ascl:1605.010]
TRIPPy: Python-based Trailed Source Photometry

Fraser, Wesley C.; Alexandersen, Mike; Schwamb, Megan E.; Marsset, Michael E.; Pike, Rosemary E.; Kavelaars, JJ; Bannister, Michele T.; Benecchi, Susan; Delsanti, Audrey

TRIPPy (TRailed Image Photometry in Python) uses a pill-shaped aperture, a rectangle described by three parameters (trail length, angle, and radius) to improve photometry of moving sources over that done with circular apertures. It can generate accurate model and trailed point-spread functions from stationary background sources in sidereally tracked images. Appropriate aperture correction provides accurate, unbiased flux measurement. TRIPPy requires numpy, scipy, matplotlib, Astropy (ascl:1304.002), and stsci.numdisplay; emcee (ascl:1303.002) and SExtractor (ascl:1010.064) are optional.

[ascl:1405.008]
TRIPP: Time Resolved Imaging Photometry Package

Geckeler, Ralf D.; Schuh, Sonja; Dreizler, Stefan; Deetjen, Jochen; Gleissner, Thomas; Risse, Patrick; Rauch, Thomas; Göhler, Eckart; Hügelmeyer, Simon; Husser, Tim-Oliver; Israel, Holger; Benlloch-Garcia, Sara; Pottschmidt, Katja; Wilms, Jörn

Written in IDL, TRIPP performs CCD time series reduction and analysis. It provides an on-line check of the incoming frames, performs relative aperture photometry and provides a set of time series tools, such as calculation of periodograms including false alarm probability determination, epoc folding, sinus fitting, and light curve simulations.

[ascl:1210.014]
TRIP: General computer algebra system for celestial mechanics

TRIP is an interactive computer algebra system that is devoted to perturbation series computations, and specially adapted to celestial mechanics. Its development started in 1988, as an upgrade of the special purpose FORTRAN routines elaborated by J. Laskar for the demonstration of the chaotic behavior of the Solar System. TRIP is a mature and efficient tool for handling multivariate generalized power series, and embeds two kernels, a symbolic and a numerical kernel. This numerical kernel communicates with Gnuplot or Grace to plot the graphics and allows one to plot the numerical evaluation of symbolic objects.

[ascl:1508.009]
Trilogy: FITS image conversion software

Trilogy automatically scales and combines FITS images to produce color or grayscale images using Python scripts. The user assigns images to each color channel (RGB) or a single image to grayscale luminosity. Trilogy determines the intensity scaling automatically and independently in each channel to display faint features without saturating bright features. Each channel's scaling is determined based on a sample of the image (or summed images) and two input parameters. One parameter sets the output luminosity of "the noise," currently determined as 1-sigma above the sigma-clipped mean. The other parameter sets what fraction of the data (if any) in the sample region should be allowed to saturate. Default values for these parameters (0.15% and 0.001%, respectively) work well, but the user is able to adjust them. The scaling is accomplished using the logarithmic function y = a log(kx + 1) clipped between 0 and 1, where a and k are constants determined based on the data and desired scaling parameters as described above.

[ascl:1612.019]
Trident: Synthetic spectrum generator

Trident creates synthetic absorption-line spectra from astrophysical hydrodynamics simulations. It uses the yt package (ascl:1011.022) to read in simulation datasets and extends it to provide realistic synthetic observations appropriate for studies of the interstellar, circumgalactic, and intergalactic media.

[ascl:1508.007]
TreeCorr: Two-point correlation functions

TreeCorr efficiently computes two-point correlation functions. It can compute correlations of regular number counts, weak lensing shears, or scalar quantities such as convergence or CMB temperature fluctuations. Two-point correlations may be auto-correlations or cross-correlations, including any combination of shear, kappa, and counts. Two-point functions can be done with correct curved-sky calculation using RA, Dec coordinates, on a Euclidean tangent plane, or in 3D using RA, Dec and a distance. The front end is written in Python, which can be used as a Python module or as a standalone executable using configuration files; the actual computation of the correlation functions is done in C++ using ball trees (similar to kd trees), making the calculation extremely efficient, and when available, OpenMP is used to run in parallel on multi-core machines.

[ascl:1412.011]
TraP: Transients discovery pipeline for image-plane surveys

The TraP is a pipeline for detecting and responding to transient and variable sources in a stream of astronomical images. Images are initially processed using a pure-Python source-extraction package, PySE (ascl:1805.026), which is bundled with the TraP. Source positions and fluxes are then loaded into a SQL database for association and variability detection. The database structure allows for estimation of past upper limits on newly detected sources, and for forced fitting of previously detected sources which have since dropped below the blind-extraction threshold. Developed with LOFAR data in mind, the TraP has been used with data from other radio observatories.

[ascl:1703.010]
TransitSOM: Self-Organizing Map for Kepler and K2 transits

A self-organizing map (SOM) can be used to identify planetary candidates from Kepler and K2 datasets with accuracies near 90% in distinguishing known Kepler planets from false positives. TransitSOM classifies a Kepler or K2 lightcurve using a self-organizing map (SOM) created and pre-trained using PyMVPA (ascl:1703.009). It includes functions for users to create their own SOMs.

[ascl:1704.008]
Transit: Radiative-transfer code for planetary atmospheres

Cubillos, Patricio; Blecic, Jasmina; Harrington, Joe; Rojo, Patricio; Foster, Austin J.; Stemm, Madison; Challener,Ryan; Foster, Andrew S. D.

Transit calculates the transmission or emission spectrum of a planetary atmosphere with application to extrasolar-planet transit and eclipse observations, respectively. It computes the spectra by solving the one-dimensional line-by-line radiative-transfer equation for an atmospheric model.

[ascl:1011.018]
Transit of a Spherical Planet of a Stellar Chromosphere which is Geometrically Thin

Transit light curves for stellar continua have only one minimum and a "U" shape. By contrast, transit curves for optically thin chromospheric emission lines can have a "W" shape because of stellar limb-brightening. We calculate light curves for an optically thin shell of emission and fit these models to time-resolved observations of Si IV absorption by the planet HD209458b. We find that the best fit Si IV absorption model has R_p,SIV/R_*= 0.34+0.07-0.12, similar to the Roche lobe of the planet. While the large radius is only at the limit of statistical significance, we develop formulae applicable to transits of all optically thin chromospheric emission lines.

[ascl:1611.008]
Transit Clairvoyance: Predicting multiple-planet systems for TESS

Transit Clairvoyance uses Artificial Neural Networks (ANNs) to predict the most likely short period transiters to have additional transiters, which may double the discovery yield of the TESS (Transiting Exoplanet Survey Satellite). Clairvoyance is a simple 2-D interpolant that takes in the number of planets in a system with period less than 13.7 days, as well as the maximum radius amongst them (in Earth radii) and orbital period of the planet with maximum radius (in Earth days) in order to predict the probability of additional transiters in this system with period greater than 13.7 days.

[ascl:1106.014]
Transit Analysis Package (TAP and autoKep): IDL Graphical User Interfaces for Extrasolar Planet Transit Photometry

We present an IDL graphical user interface-driven software package designed for the analysis of extrasolar planet transit light curves. The Transit Analysis Package (TAP) software uses Markov Chain Monte Carlo (MCMC) techniques to fit light curves using the analytic model of Mandel and Agol (2002). The package incorporates a wavelet based likelihood function developed by Carter and Winn (2009) which allows the MCMC to assess parameter uncertainties more robustly than classic chi-squared methods by parameterizing uncorrelated "white" and correlated "red" noise. The software is able to simultaneously analyze multiple transits observed in different conditions (instrument, filter, weather, etc). The graphical interface allows for the simple execution and interpretation of Bayesian MCMC analysis tailored to a user's specific data set and has been thoroughly tested on ground-based and Kepler photometry. AutoKep provides a similar GUI for the preparation of Kepler MAST archive data for analysis by TAP or any other analysis software. This paper describes the software release and provides instructions for its use.

[ascl:1501.011]
transfer: The Sloan Digital Sky Survey Data Transfer Infrastructure

The Sloan Digital Sky Survey (SDSS) produces large amounts of data daily. transfer, written in Python, provides the effective automation needed for daily data transfer operations and management and operates essentially free of human intervention. This package has been tested and used successfully for several years.

[ascl:1601.001]
TRADES: TRAnsits and Dynamics of Exoplanetary Systems

TRADES (TRAnsits and Dynamics of Exoplanetary Systems) simultaneously fits observed radial velocities and transit times data to determine the orbital parameters of exoplanetary systems from observational data. It uses a dynamical simulator for N-body systems that also fits the available data during the orbital integration and determines the best combination of the orbital parameters using grid search, χ2 minimization, genetic algorithms, particle swarm optimization, and bootstrap analysis.

[ascl:1304.011]
TPZ: Trees for Photo-Z

TPZ, a parallel code written in python, produces robust and accurate photometric redshift PDFs by using prediction tree and random forests. The code also produces ancillary information about the sample used, such as prior unbiased errors estimations (giving an estimation of performance) and a ranking of importance of variables as well as a map of performance indicating where extra training data is needed to improve overall performance. It is designed to be easy to use and a tutorial is available.

[ascl:1305.003]
TPM: Tree-Particle-Mesh code

TPM carries out collisionless (dark matter) cosmological N-body simulations, evolving a system of N particles as they move under their mutual gravitational interaction. It combines aspects of both Tree and Particle-Mesh algorithms. After the global PM forces are calculated, spatially distinct regions above a given density contrast are located; the tree code calculates the gravitational interactions inside these denser objects at higher spatial and temporal resolution. The code is parallel and uses MPI for message passing.

[ascl:1603.012]
tpipe: Searching radio interferometry data for fast, dispersed transients

Visibilities from radio interferometers have not traditionally been used to study the fast transient sky. Millisecond transients (e.g., fast radio bursts) and periodic sources (e.g., pulsars) have been studied with single-dish radio telescopes and a software stack developed over the past few decades. tpipe is an initial attempt to develop the fast transient algorithms for visibility data. Functions exist for analysis of visibilties, such as reading data, flagging data, applying interferometric gain calibration, and imaging. These functions are given equal footing as time-domain techniques like filters and dedispersion.

tpipe has been largely superseded by rtpipe (ascl:1706.002).

[ascl:1904.021]
TP2VIS: Total Power Map to Visibilities

TP2VIS creates visibilities from a single dish cube; the TP visibilities can be combined with the interferometric visibilities in a joint deconvolution using, for example, CASA's tclean() method. TP2VIS requires CASA 5.4 (ascl:1107.013) or above.

[ascl:1507.006]
Toyz: Large datasets and astronomical images analysis framework

Toyz is a python web framework that allows scientists to interact with large images and data sets stored on a remote server. A web application is run on the server containing the data and clients are run from web browsers on the user's computer. Toyz displays large FITS images also also renders any image format supported by Pillow (a fork of the Python Imaging Library), contains a GUI to interact with linked plots, and offers a customizable framework that allows students and researchers to create their own work spaces inside a Toyz environment. Astro-Toyz extends the features of the Toyz image viewer, allowing users to view world coordinates and align images based on their WCS.

[ascl:1404.006]
TORUS: Radiation transport and hydrodynamics code

TORUS is a flexible radiation transfer and radiation-hydrodynamics code. The code has a basic infrastructure that includes the AMR mesh scheme that is used by several physics modules including atomic line transfer in a moving medium, molecular line transfer, photoionization, radiation hydrodynamics and radiative equilibrium. TORUS is useful for a variety of problems, including magnetospheric accretion onto T Tauri stars, spiral nebulae around Wolf-Rayet stars, discs around Herbig AeBe stars, structured winds of O supergiants and Raman-scattered line formation in symbiotic binaries, and dust emission and molecular line formation in star forming clusters. The code is written in Fortran 2003 and is compiled using a standard Gnu makefile. The code is parallelized using both MPI and OMP, and can use these parallel sections either separately or in a hybrid mode.

[ascl:1101.010]
TOPCAT: Tool for OPerations on Catalogues And Tables

TOPCAT is an interactive graphical viewer and editor for tabular data. Its aim is to provide most of the facilities that astronomers need for analysis and manipulation of source catalogues and other tables, though it can be used for non-astronomical data as well. It understands a number of different astronomically important formats (including FITS and VOTable) and more formats can be added.

It offers a variety of ways to view and analyse tables, including a browser for the cell data themselves, viewers for information about table and column metadata, and facilities for 1-, 2-, 3- and higher-dimensional visualisation, calculating statistics and joining tables using flexible matching algorithms. Using a powerful and extensible Java-based expression language new columns can be defined and row subsets selected for separate analysis. Table data and metadata can be edited and the resulting modified table can be written out in a wide range of output formats.

It is a stand-alone application which works quite happily with no network connection. However, because it uses Virtual Observatory (VO) standards, it can cooperate smoothly with other tools in the VO world and beyond, such as VODesktop, Aladin and ds9. Between 2006 and 2009 TOPCAT was developed within the AstroGrid project, and is offered as part of a standard suite of applications on the AstroGrid web site, where you can find information on several other VO tools.

The program is written in pure Java and available under the GNU General Public Licence. It has been developed in the UK within the Starlink and AstroGrid projects, and under PPARC and STFC grants. Its underlying table processing facilities are provided by STIL.

[ascl:1104.001]
TomograPy: A Fast, Instrument-Independent, Solar Tomography Software

TomograPy is an open-source software freely available on the Python Package Index that can perform fast tomographic inversions that scale linearly with the number of measurements, linearly with the length of the reconstruction cube (and not the number of voxels) and linearly with the number of cores and can use data from different sources and with a variety of physical models. For performance, TomograPy uses a parallelized-projection algorithm. It relies on the World Coordinate System standard to manage various data sources. A variety of inversion algorithms are provided to perform the tomographic-map estimation. A test suite is provided along with the code to ensure software quality. Since it makes use of the Siddon algorithm it is restricted to rectangular parallelepiped voxels but the spherical geometry of the corona can be handled through proper use of priors.

[ascl:1209.007]
TMCalc: Fast estimation of stellar metallicity [Fe/H]

TMCalc is a C code developed as an extension to ARES. Using the line list given, the code can be used as a precise and fast indicator of the spectroscopic temperature and metallicity for dwarf FKG stars with effective temperatures ranging from 4500 K to 6500 K and with [Fe/H] ranging from -0.8 dex to 0.4 dex.

[ascl:1605.005]
TMBIDL: Single dish radio astronomy data reduction package

The IDL package reduces and analyzes radio astronomy data. It translates SDFITS files into TMBIDL format, and can average and display spectra, remove baselines, and fit Gaussian models.

[ascl:1212.015]
TMAP: Tübingen NLTE Model-Atmosphere Package

The Tübingen NLTE Model-Atmosphere Package (TMAP) is a tool to calculate stellar atmospheres in spherical or plane-parallel geometry in hydrostatic and radiative equilibrium allowing departures from local thermodynamic equilibrium (LTE) for the population of atomic levels. It is based on the Accelerated Lambda Iteration (ALI) method and is able to account for line blanketing by metals. All elements from hydrogen to nickel may be included in the calculation with model atoms which are tailored for the aims of the user.

[ascl:1512.014]
TM: Torus Mapper

TM (Torus Mapper) produces models for orbits in action-angle coordinates in axisymmetric potentials using torus mapping, a non-perturbative technique for creating orbital tori for specified values of the action integrals. It can compute a star's position at any time given an orbital torus and a star’s position at a reference time, and also provides a way to choose initial conditions for N-body simulations of realistic disc galaxies that start in perfect equilibrium. TM provides some advantages over use of a standard time-stepper to create orbits.

[ascl:1109.021]
TLUSTY: Stellar Atmospheres, Accretion Disks, and Spectroscopic Diagnostics

TLUSTY is a user-oriented package written in FORTRAN77 for modeling stellar atmospheres and accretion disks and wide range of spectroscopic diagnostics. In the program's maximum configuration, the user may start from scratch and calculate a model atmosphere of a chosen degree of complexity, and end with a synthetic spectrum in a wavelength region of interest for an arbitrary stellar rotation and an arbitrary instrumental profile. The user may also model the vertical structure of annuli of an accretion disk.

[ascl:1108.012]
TITAN: General-purpose Radiation Hydrodynamics Code

TITAN is a general-purpose radiation hydrodynamics code developed at the Laboratory for Computational Astrophysics (NCSA, University of Illinois at Urbana-Champaign). TITAN solves the coupled sets of radiation transfer and fluid dynamics equations on an adaptive mesh in one spatial dimension.

[ascl:1208.008]
TiRiFiC: Tilted Ring Fitting Code

Tilted Ring Fitting Code (TiRiFiC) is a prototype computer program to construct simulated (high-resolution) astronomical spectroscopic 3d-observations (data cubes) of simple kinematical and morphological models of rotating (galactic) disks. It is possible to automatically optimize the parameterizations of constructed model disks to fit spectroscopic (3d-) observations via a χ2 minimization. TiRiFiC is currently implemented as an add-on to the Groningen Image Processing System (GIPSY) software package and attempts to provide a method to automatically fit an extended tilted-ring model directly to a data cube.

[ascl:1111.015]
TIPSY: Code for Display and Analysis of N-body Simulations

The development of TIPSY was motivated by the need to quickly display and analyze the results of N-body simulations. Most data visualization packages are designed for the display of gridded data, and hence are unsuitable for use with particle data. Therefore, a special package was built that could easily perform the following functions:

1.) Display particle positions (as points), and velocities (as line segments) from an arbitrary viewpoint;

2.) Zoom in to a chosen position. Due to their extremely clustered nature, structure of interest in an N-body simulation is often so small that it cannot be seen when looking at the simulation as a whole;

3.) Color particles to display scalar fields. Examples of such fields are potential energy, or for SPH particles, density and temperature;

4.) Selection of a subset of the particles for display and analysis. Regions of interest are generally small subsets of the simulation;

5.) Following selected particles from one timestep to another; and,

6.) Finding cumulative properties of a collection of particles. This usually involves just a sum over the particles.

The basic data structure is an array of particle structures. Since TIPSY was built for use with cosmological N-body simulations, there are actually three separate arrays for each of the types of particle used in such simulations: collisionless particles, SPH particles, and star particles. A single timestep is read into these arrays from a disk file. Display is done by finding the x and y coordinates of the particles in the rotated coordinate system, and storing them in arrays. Screen coordinates are calculated from these arrays according to the current zoom factor. Also, a software Z-buffer is maintained to save time if many particles project to the same screen pixel. There are several types of display. An "all plot" displays all particles colored according to their type. A "radial plot" will color particles according to the projection of the velocity along the line-of-sight. A "gas plot" will color gas according to SPH quantities such as density, temperature, neutral hydrogen fraction, etc. Subsets of particles are maintained using boxes." A box structure contains a bounding box, and an array of pointers to particles within the box. All display and analysis functions are performed on the "active box." By default all particles are loaded into box 0, which becomes the active box. If a new timestep is read from disk, all boxes are destroyed. A selection of particles can be followed between timesteps via a "mark" array. Marked particles are displayed in a different color, and the analysis functions can be told to only operate on the marked particles.

[ascl:1010.057]
Tiny Tim: Simulated Hubble Space Telescope PSFs

Tiny Tim generates simulated Hubble Space Telescope point spread functions (PSFs). It is written in C and distributed as source code and runs on a wide variety of UNIX and VMS systems. Tiny Tim includes mirror zonal errors, time dependent aberrations (for the pre-repair instruments), field dependent obscuration patterns (for WF/PC-1 and WFPC2), and filter passband effects. It can produce a normally sampled or subsampled PSF. Output is a FITS image file.

[ascl:1206.012]
Time Utilities

Time Utilities are software tools that, in principal, allow one to calculate BJD to a precision of 1 μs for any target from anywhere on Earth or from any spacecraft. As the quality and quantity of astrophysical data continue to improve, the precision with which certain astrophysical events can be timed becomes limited not by the data themselves, but by the manner, standard, and uniformity with which time itself is referenced. While some areas of astronomy (most notably pulsar studies) have required absolute time stamps with precisions of considerably better than 1 minute for many decades, recently new areas have crossed into this regime. In particular, in the exoplanet community, we have found that the (typically unspecified) time standards adopted by various groups can differ by as much as a minute. Left uncorrected, this ambiguity may be mistaken for transit timing variations and bias eccentricity measurements. We recommend using BJD_TDB, the Barycentric Julian Date in the Barycentric Dynamical Time standard for any astrophysical event. The BJD_TDB is the most practical absolute time stamp for extraterrestrial phenomena, and is ultimately limited by the properties of the target system. We compile a general summary of factors that must be considered in order to achieve timing precisions ranging from 15 minutes to 1 μs, and provide software for download and online webapps for use.

[ascl:1609.021]
TIDEV: Tidal Evolution package

TIDEV (Tidal Evolution package) calculates the evolution of rotation for tidally interacting bodies using Efroimsky-Makarov-Williams (EMW) formalism. The package integrates tidal evolution equations and computes the rotational and dynamical evolution of a planet under tidal and triaxial torques. TIDEV accounts for the perturbative effects due to the presence of the other planets in the system, especially the secular variations of the eccentricity. Bulk parameters include the mass and radius of the planet (and those of the other planets involved in the integration), the size and mass of the host star, the Maxwell time and Andrade's parameter. TIDEV also calculates the time scale that a planet takes to be tidally locked as well as the periods of rotation reached at the end of the spin-orbit evolution.

[ascl:1212.014]
Thrust: Productivity-Oriented Library for CUDA

Thrust is a parallel algorithms library which resembles the C++ Standard Template Library (STL). Thrust's high-level interface greatly enhances programmer productivity while enabling performance portability between GPUs and multicore CPUs. Interoperability with established technologies (such as CUDA, TBB, and OpenMP) facilitates integration with existing software.

[ascl:1807.010]
THOR: Global Circulation Model for planetary atmospheres

THOR solves the three-dimensional nonhydrostatic Euler equations. The code implements an icosahedral grid for the poles where converging meridians lead to increasingly smaller time steps; irregularities in the grid are smoothed using spring dynamics. THOR is designed to run on graphics processing units (GPUs) and is part of the open-source Exoclimes Simulation Platform.

[ascl:1711.016]
Thindisk: Protoplanetary disk model

Thindisk computes the line emission from a geometrically thin protoplanetary disk. It creates a datacube in FITS format that can be processed with a data reduction package (such as GILDAS, ascl:1305.010) to produce synthetic images and visibilities. These synthetic data can be compared with observations to determine the properties (e.g. central mass or inclination) of an observed disk. The disk is assumed to be in Keplerian rotation at a radius lower than the centrifugal radius (which can be set to a large value, for a purely Keplerian disk), and in infall with rotation beyond the centrifugal radius.

[ascl:1112.003]
THERMINATOR 2: THERMal heavy IoN generATOR 2

THERMINATOR is a Monte Carlo event generator dedicated to studies of the statistical production of particles in relativistic heavy-ion collisions. The increased functionality of the code contains the following features: The input of any shape of the freeze-out hypersurface and the expansion velocity field, including the 3+1 dimensional profiles, in particular those generated externally with various hydrodynamic codes. The hypersufraces may have variable thermal parameters, which allows for studies departing significantly from the mid-rapidity region, where the baryon chemical potential becomes large. We include a library of standard sets of hypersurfaces and velocity profiles describing the RHIC Au+Au data at sqrt(s_(NN)) = 200 GeV for various centralities, as well as those anticipated for the LHC Pb+Pb collisions at sqrt(s_(NN)) = 5.5 TeV. A separate code, FEMTO-THERMINATOR, is provided to carry out the analysis of femtoscopic correlations which are an important source of information concerning the size and expansion of the system. We also include several useful scripts that carry out auxiliary tasks, such as obtaining an estimate of the number of elastic collisions after the freeze-out, counting of particles flowing back into the fireball and violating causality (typically very few), or visualizing various results: the particle p_T-spectra, the elliptic flow coefficients, and the HBT correlation radii. We also investigate the problem of the back-flow of particles into the hydrodynamic region, as well as estimate the elastic rescattering in terms of trajectory crossings. The package is written in C++ and uses the CERN ROOT environment.

[ascl:1308.013]
THELI GUI: Optical, near- & mid-infrared imaging data reduction

THELI is an easy-to-use, end-to-end pipeline for the reduction of any optical, near-IR and mid-IR imaging data. It combines a variety of processing algorithms and third party software into a single, homogeneous tool. Over 90 optical and infrared instruments at observatories world-wide are pre-configured; more can be added by the user. The code's online appendix contains three walk-through examples using public data (optical, near-IR and mid-IR) and additional online documentation is available for training and troubleshooting.

[ascl:1706.008]
the-wizz: Clustering redshift estimation code

the-wizz clusters redshift estimates for any photometric unknown sample in a survey. The software is composed of two main parts: a pair finder and a pdf maker. The pair finder finds spatial pairs and stores the indices of all closer pairs around target reference objects in an output HDF5 data file. Users then query this data file using the indices of their unknown sample to produce an output clustering-z.

[ascl:1604.008]
The Tractor: Probabilistic astronomical source detection and measurement

The Tractor optimizes or samples from models of astronomical objects. The approach is generative: given astronomical sources and a description of the image properties, the code produces pixel-space estimates or predictions of what will be observed in the images. This estimate can be used to produce a likelihood for the observed data given the model: assuming the model space actually includes the truth (it doesn’t, in detail), then if we had the optimal model parameters, the predicted image would differ from the actually observed image only by noise. Given a noise model of the instrument and assuming pixelwise independent noise, the log-likelihood is the negative chi-squared difference: (image - model) / noise.

[ascl:1407.001]
The Starfish Diagram: Statistical visualization tool

The Starfish Diagram is a statistical visualization tool that simultaneously displays the properties of an individual and its parent sample through a series of histograms. The code is useful for large datasets for which one needs to understand the standing or significance of a single entry.

[ascl:1701.001]
The Joker: A custom Monte Carlo sampler for binary-star and exoplanet radial velocity data

Given sparse or low-quality radial-velocity measurements of a star, there are often many qualitatively different stellar or exoplanet companion orbit models that are consistent with the data. The consequent multimodality of the likelihood function leads to extremely challenging search, optimization, and MCMC posterior sampling over the orbital parameters. The Joker is a custom-built Monte Carlo sampler that can produce a posterior sampling for orbital parameters given sparse or noisy radial-velocity measurements, even when the likelihood function is poorly behaved. The method produces correct samplings in orbital parameters for data that include as few as three epochs. The Joker can therefore be used to produce proper samplings of multimodal pdfs, which are still highly informative and can be used in hierarchical (population) modeling.

[ascl:1405.003]
The Hammer: An IDL Spectral Typing Suite

The Hammer can classify spectra in a variety of formats with targets spanning the MK spectral sequence. It processes a list of input spectra by automatically estimating each object's spectral type and measuring activity and metallicity tracers in late type stars. Once automatic processing is complete, an interactive interface allows the user to manually tweak the final assigned spectral type through visual comparison with a set of templates.

[ascl:1906.004]
The Exo-Striker: Transit and radial velocity interactive fitting tool for orbital analysis and N-body simulations

The Exo-Striker analyzes exoplanet orbitals, performs N-body simulations, and models the RV stellar reflex motion caused by dynamically interacting planets in multi-planetary systems. It offers a broad range of tools for detailed analysis of transit and Doppler data, including power spectrum analysis for Doppler and transit data; Keplerian and dynamical modeling of multi-planet systems; MCMC and nested sampling; Gaussian Processes modeling; and a long-term stability check of multi-planet systems. The Exo-Striker can also analyze Mean Motion Resonance (MMR) analysis, create fast fully interactive plots, and export ready-to-use LaTeX tables with best-fit parameters, errors, and statistics. It combines Fortran efficiency and Python flexibility and is cross-platform compatible (MAC OS, Linux, Windows). The tool relies on a number of open-source packages, including RVmod engine, emcee (ascl:1303.002), batman (ascl:1510.002), celerite (ascl:1709.008), and dynesty (ascl:1809.013).

[ascl:1105.003]
The DTFE public software: The Delaunay Tessellation Field Estimator code

We present the DTFE public software, a code for reconstructing fields from a discrete set of samples/measurements using the maximum of information contained in the point distribution. The code is written in C++ using the CGAL library and is parallelized using OpenMP. The software was designed for the analysis of cosmological data but can be used in other fields where one must interpolate quantities given at a discrete point set. The software comes with a wide suite of options to facilitate the analysis of 2- and 3-dimensional data and of both numerical simulations and galaxy redshift surveys. For comparison purposes, the code also implements the TSC and SPH grid interpolation methods. The code comes with an extensive user guide detailing the program options, examples and the inner workings of the code.

[ascl:1602.010]
The Cannon: Data-driven method for determining stellar parameters and abundances from stellar spectra

The Cannon is a data-driven method for determining stellar labels (physical parameters and chemical abundances) from stellar spectra in the context of vast spectroscopic surveys. It fits for the spectral model given training spectra and labels, with the polynomial order for the spectral model decided by the user, infers labels for the test spectra, and provides diagnostic output for monitoring and evaluating the process. It offers SNR-independent continuum normalization, performs well at lower signal-to-noise, and is very accurate.

[ascl:1905.018]
THALASSA: Orbit propagator for near-Earth and cislunar space

THALASSA (Tool for High-Accuracy, Long-term Analyses for SSA) propagates orbits for bodies in the Earth-Moon-Sun system. Written in Fortran, it integrates either Newtonian equations in Cartesian coordinates or regularized equations of motion with the LSODAR (Livermore Solver for Ordinary Differential equations with Automatic Root-finding). THALASSA is a command-line tool; the repository also includes some Python3 scripts to perform batch propagations.

[ascl:1303.012]
TGCat: Chandra Transmission Grating Catalog and Archive

TGCat is an archive of Chandra transmission grating spectra and a suite of software for processing such data. Users can browse and categorize Chandra gratings observations quickly and easily, generate custom plots of resulting response corrected spectra on-line without the need for special software and download analysis ready products from multiple observations in one convenient operation. Data processing for the catalog is done with a suite of ISIS/S-Lang scripts; the software is available for download. These ISIS scripts wrap and call CIAO tools for reprocessing from "Level 1" (acis_process_events or hrc_process_events) through "Level 2" (binned spectra, via tg_resolve_events and tgextract), compute responses (grating "RMFs" and "ARFs", via mkgrmf and mkgarf), and make summary plots.

[ascl:1505.019]
TFIT: Mixed-resolution data set photometry package

Laidler, Victoria G.; Papovich, Casey; Grogin, Norman A.; Idzi, Rafal; Dickinson, Mark; Ferguson, Henry C.; Hilbert, Bryan; Clubb, Kelsey; Ravindranath, Swara

TFIT measures galaxy photometry using prior knowledge of sources in a deep, high‐resolution image (HRI) to improve photometric measurements of objects in a corresponding low‐resolution image (LRI) of the same field, usually at a different wavelength. For background‐limited data, this technique produces optimally weighted photometry that maximizes signal‐to‐noise ratio (S/N). For objects not significantly detected in the low‐resolution image, it provides useful and quantitative information for setting upper limits.

This code is no longer updated and has been superseded by T-PHOT (ascl:1609.001).

[ascl:1611.002]
tf_unet: Generic convolutional neural network U-Net implementation in Tensorflow

tf_unet mitigates radio frequency interference (RFI) signals in radio data using a special type of Convolutional Neural Network, the U-Net, that enables the classification of clean signal and RFI signatures in 2D time-ordered data acquired from a radio telescope. The code is not tied to a specific segmentation and can be used, for example, to detect radio frequency interference (RFI) in radio astronomy or galaxies and stars in widefield imaging data. This U-Net implementation can outperform classical RFI mitigation algorithms.

[ascl:1210.015]
Tempo2: Pulsar Timing Package

Tempo2 is a pulsar timing package developed to be used both for general pulsar timing applications and also for pulsar timing array research in which data-sets from multiple pulsars need to be processed simultaneously. It was initially developed by George Hobbs and Russell Edwards as part of the Parkes Pulsar Timing Array project. Tempo2 is based on the original Tempo (ascl:1509.002) code and can be used (from the command-line) in a similar fashion. It is very versatile and can be extended by plugins.

[ascl:1509.002]
Tempo: Pulsar timing data analysis

Nice, D; Demorest, P.; Stairs, I.; Manchester, R.; Taylor, J.; Peters, W.; Weisberg, J.; Irwin, A.; Wex, N.; Huang, Y.

Tempo analyzes pulsar timing data. Pulse times of arrival (TOAs), pulsar model parameters, and coded instructions are read from one or more input files. The TOAs are fitted by a pulse timing model incorporating transformation to the solar-system barycenter, pulsar rotation and spin-down and, where necessary, one of several binary models. Program output includes parameter values and uncertainties, residual pulse arrival times, chi-squared statistics, and the covariance matrix of the model. In prediction mode, ephemerides of pulse phase behavior (in the form of polynomial expansions) are calculated from input timing models. Tempo is the basis for the Tempo2 (ascl:1210.015) code.

[ascl:1405.002]
TelFit: Fitting the telluric absorption spectrum

TelFit calculates the best-fit telluric absorption spectrum in high-resolution optical and near-IR spectra. The best-fit model can then be divided out to remove the telluric contamination. Written in Python, TelFit is essentially a wrapper to LBLRTM, the Line-By-Line Radiative Transfer Model, and simplifies the process of generating a telluric model.

[ascl:1505.031]
TEA: Thermal Equilibrium Abundances

TEA (Thermal Equilibrium Abundances) calculates gaseous molecular abundances under thermochemical equilibrium conditions. Given a single T,P point or a list of T,P pairs (the thermal profile of an atmosphere) and elemental abundances, TEA calculates mole fractions of the desired molecular species. TEA uses 84 elemental species and thermodynamical data for more then 600 gaseous molecular species, and can adopt any initial elemental abundances.

[ascl:1807.024]
TBI: Three-Body Integration

Three-Body Integration performs numerical n-body simulations for mapping conditions for close approaches for the relevant parameter space of configurations and mass values of two white dwarfs and a third star. Low tertiary masses of 0.1M⊙ can be studied, and the collision probability can be estimated with good confidence for the case of nearly equal mass white dwarfs.

[ascl:1305.014]
TAU: 1D radiative transfer code for transmission spectroscopy of extrasolar planet atmospheres

TAU is a 1D line-by-line radiative transfer code for modeling transmission spectra of close-in extrasolar planets. The code calculates the optical path through the planetary atmosphere of the radiation from the host star and quantifies the absorption due to the modeled composition in a transmission spectrum of transit depth as a function of wavelength. The code is written in C++ and is parallelized using OpenMP.

[ascl:1402.018]
TARDIS: Temperature And Radiative Diffusion In Supernovae

TARDIS creates synthetic spectra for supernova ejecta and is sufficiently fast to allow exploration of the complex parameter spaces of models for SN ejecta. TARDIS uses Monte Carlo methods to obtain a self-consistent description of the plasma state and to compute a synthetic spectrum. It is written in Python with a modular design that facilitates the implementation of a range of physical approximations that can be compared to assess both accuracy and computational expediency; this allows users to choose a level of sophistication appropriate for their application.

[ascl:1306.007]
Tapir: A web interface for transit/eclipse observability

Tapir is a set of tools, written in Perl, that provides a web interface for showing the observability of periodic astronomical events, such as exoplanet transits or eclipsing binaries. The package provides tools for creating finding charts for each target and airmass plots for each event. The code can access target lists that are stored on-line in a Google spreadsheet or in a local text file.

[ascl:1503.003]
TAME: Tool for Automatic Measurement of Equivalent-width

TAME measures the equivalent width (EWs) in high-resolution spectra. Written by IDL, TAME provides the EWs of spectral lines by profile fitting in an automatic or interactive mode and is reliable for measuring EWs in a spectrum with a spectral resolution of R ≳ 20000. It offers an interactive mode for more flexible measurement of the EW and a fully automatic mode that can simultaneously measure the EWs for a large set of lines.

[ascl:1202.004]
TALYS: Nuclear Reaction Simulator

TALYS simulates nuclear reactions which involve neutrons, gamma-rays, protons, deuterons, tritons, helions and alpha-particles, in the 1 keV-200MeV energy range. A suite of nuclear reaction models has been implemented into a single code system, enabling one to evaluate basically all nuclear reactions beyond the resonance range. In particular, TALYS estimates the Maxwellian-averaged reaction rates that are of astrophysical relevance. This enables reaction rates to be calculated with increased accuracy and reliability and the approximations of previous codes to be investigated. The TALYS predictions for the thermonuclear rates of relevance to astrophysics are detailed and compared with those derived by widely-used codes for the same nuclear ingredients. TALYS predictions may differ significantly from those of previous codes, in particular for nuclei for which no or little nuclear data is available. The pre-equilibrium process is shown to influence the astrophysics rates of exotic neutron-rich nuclei significantly. The TALYS code provides a tool to estimate all nuclear reaction rates of relevance to astrophysics with improved accuracy and reliability.

[submitted]
taktent: A Python framework for agent-based simulations of SETI observations

This Python package allows the user to setup and run an agent-based simulation of a SETI survey. The package allows the creation of a population of observing and transmitting civilisations. Each transmitter and observer conducts their activities according to an input strategy. The success of observers and transmitters can then be recorded, and multiple simulations can be run for Monte Carlo Realisation.

This package is therefore a flexible framework in which to simulate and test different SETI strategies, both as an Observer and as a Transmitter. It is primarily designed with radio SETI in mind, but is sufficiently flexible to simulate all forms of electromagnetic SETI, and potentially neutrino and gravitational wave SETI.

[ascl:1602.013]
TailZ: Redshift distributions estimator of photometric samples of galaxies

TailZ estimates redshift distributions of photometric samples of galaxies selected photometrically given a subsample with measured spectroscopic redshifts. The approach uses a non-parametric Voronoi tessellation density estimator to interpolate the galaxy distribution in the redshift and photometric color space. The Voronoi tessellation estimator performs well at reconstructing the tails of the redshift distribution of individual galaxies and gives unbiased estimates of the first and second moments.

[ascl:1512.020]
TACT: The Action Computation Tool

The Action Computation Tool (TACT) tests methods for estimating actions, angles and frequencies of orbits in both axisymmetric and triaxial potentials, including general spherical potentials, analytic potentials (Isochrone and Harmonic oscillator), axisymmetric Stackel fudge, average generating function from orbit (AvGF), and others. It is written in C++; code is provided to compile the routines into a Python library. TM (ascl:1512.014) and LAPACK are required to access some features.

[ascl:1303.010]
TAC-maker: Transit Analytical Curve maker

TAC-maker allows for rapid and interactive calculation of synthetic planet transits by numerical computations of the integrals, allowing the use of an arbitrary limb-darkening law of the host star. This advantage together with the practically arbitrary precision of the calculations makes the code a valuable tool for the continuously increasing photometric precision of ground-based and space observations.

[ascl:1210.006]
TA-DA: A Tool for Astrophysical Data Analysis

TA-DA is a pre-compiled IDL widget-based application which greatly simplifies and improves the analysis of stellar photometric data in comparison with theoretical models and allows the derivation of stellar parameters from multi-band photometry. It is flexible and can address a number of problems, from the interpolation of stellar models or sets of stellar physical parameters in general to the computation of synthetic photometry in arbitrary filters or units. It also analyzes observed color-magnitude diagrams and allows a Bayesian derivation of stellar parameters (and extinction) based on multi-band data.

[ascl:1403.014]
T(dust) as a function of sSFR

This IDL code returns the dust temperature of a galaxy from its redshift, SFR and stellar mass; it can also predict the observed monochromatic fluxes of the galaxy. These monochromatic fluxes correspond to those of a DH SED template with the appropriate dust temperature and the appropriate normalization. Dust temperatures and fluxes predictions are only valid and provided in the redshift, stellar mass, SSFR and wavelength ranges 0 < z < 2.5, Mstar> 10^10 Msun, 10^-11 < SSFR[yr-1]< 10^-7 and 30um < lambda_rest < 2mm.

[ascl:1906.008]
T-RECS: Tiered Radio Extragalactic Continuum Simulation

Bonaldi, Anna; Bonato, Matteo; Galluzzi, Vincenzo; Harrison, Ian; Massardi, Marcella; Kay, Scott; De Zotti, Gianfranco; Brown, Michael L.

T-RECS produces radio sources catalogs with user-defined frequencies, area and depth. It models two main populations of radio galaxies, Active Galactic Nuclei (AGNs) and Star-Forming Galaxies (SFGs), and corresponding sub-populations. T-RECS is not computationally demanding and can be run multiple times, using the same catalog inputs, to project the simulated sky onto different fields.

[ascl:1609.001]
T-PHOT: PSF-matched, prior-based, multiwavelength extragalactic deconfusion photometry

Merlin, E.; Fontana, A.; Ferguson, H. C.; Dunlop, J. S.; Elbaz, D.; Bourne, N.; Bruce, V. A.; Buitrago, F.; Castellano, M.; Schreiber, C.; Grazian, A.; McLure, R. J.; Okumura, K.; Shu, X.; Wang, T.; Amorín, R.; Boutsia, K.; Cappelluti, N.; Comastri, A.; Derriere, S.; Faber, S. M.; Santini, P.

T-PHOT extracts accurate photometry from low-resolution images of extragalactic fields, where the blending of sources can be a serious problem for accurate and unbiased measurement of fluxes and colors. It gathers data from a high-resolution image of a region of the sky and uses the source positions and morphologies to obtain priors for the photometric analysis of the lower resolution image of the same field. T-PHOT handles different types of datasets as input priors, including a list of objects that will be used to obtain cutouts from the real high-resolution image, a set of analytical models (as .fits stamps), and a list of unresolved, point-like sources, useful for example for far-infrared wavelength domains. T-PHOT yields accurate estimations of fluxes within the intrinsic uncertainties of the method when systematic errors are taken into account (which can be done using a flagging code given in the output), and handles multiwavelength optical to far-infrared image photometry. T-PHOT was developed as part of the ASTRODEEP project (www.astrodeep.eu).

[ascl:1511.006]
T-Matrix: Codes for Computing Electromagnetic Scattering by Nonspherical and Aggregated Particles

The T-Matrix package includes codes to compute electromagnetic scattering by homogeneous, rotationally symmetric nonspherical particles in fixed and random orientations, randomly oriented two-sphere clusters with touching or separated components, and multi-sphere clusters in fixed and random orientations. All codes are written in Fortran-77. LAPACK-based, extended-precision, Gauss-elimination- and NAG-based, and superposition codes are available, as are double-precision superposition, parallelized double-precision, double-precision Lorenz-Mie codes, and codes for the computation of the coefficients for the generalized Chebyshev shape.

[ascl:1304.018]
SZpack: Computation of Sunyaev-Zeldovich (SZ) signals

SZpack is a numerical library which allows fast and precise computation of the Sunyaev-Zeldovich (SZ) signal for hot, moving clusters of galaxies. Both explicit numerical integration as well as approximate representation of the SZ signals can be obtained. Variations of the electron temperature and bulk velocity along the line-of-sight can be included. SZpack allows very fast and precise (<~0.001% at frequencies h nu <~ 30kT_g and electron temperature kTe ~ 75 keV) computation and its accuracy practically eliminates uncertainties related to more expensive numerical evaluation of the Boltzmann collision term. It furthermore cleanly separates kinematic corrections from scattering physics, effects that previously have not been clarified.

[ascl:1210.018]
Systemic Console: Advanced analysis of exoplanetary data

Systemic Console is a tool for advanced analysis of exoplanetary data. It comprises a graphical tool for fitting radial velocity and transits datasets and a library of routines for non-interactive calculations. Among its features are interactive plotting of RV curves and transits, combined fitting of RV and transit timing (primary and secondary), interactive periodograms and FAP estimation, and bootstrap and MCMC error estimation. The console package includes public radial velocity and transit data.

[ascl:1212.010]
Synth3: Non-magnetic spectrum synthesis code

Synth3 is a non-magnetic spectrum synthesis code. It works with model atmospheres in Kurucz format and VALD Sf line lists and features element stratification, molecular equilibrium and individual microturbulence for each line. Disk integration can be done with s3di which is included in the archive. Synth3 computes spectra emergent from the stellar atmospheres with a depth-dependent chemical composition if depth-dependent abundance is provided in the input model atmosphere file.

[ascl:1109.022]
Synspec: General Spectrum Synthesis Program

Synspec is a user-oriented package written in FORTRAN for modeling stellar atmospheres and for stellar spectroscopic diagnostics. It assumes an existing model atmosphere, calculated previously with Tlusty or taken from the literature (for instance, from the Kurucz grid of models). The opacity sources (continua, atomic and molecular lines) are fully specified by the user. An arbitrary stellar rotation and instrumental profile can be applied to the synthetic spectrum.

[ascl:1811.001]
synphot: Synthetic photometry using Astropy

Synphot simulates photometric data and spectra, observed or otherwise. It can incorporate the user's filters, spectra, and data, and use of a pre-defined standard star (Vega), bandpass, or extinction law. synphot can also construct complicated composite spectra using different models, simulate observations, and compute photometric properties such as count rate, effective wavelength, and effective stimulus. It can manipulate a spectrum by, for example, applying redshift, or normalize it to a given flux value in a given bandpass. Synphot can also sample a spectrum at given wavelengths, plot a quick-view of a spectrum, and perform repetitive operations such as simulating the observations of multiple type of sources through multiple bandpasses. Synphot understands Astropy (ascl:1304.002) models and units and is an Astropy affiliated package.

[ascl:1010.055]
SYNOW: A Highly Parameterized Spectrum Synthesis Code for Direct Analysis of SN Spectra

SYNOW is a highly parameterized spectrum synthesis code used primarily for direct (empirical) analysis of SN spectra. The code is based on simple assumptions : spherical symmetry; homologous expansion; a sharp photosphere that emits a blackbody continuous spectrum; and line formation by resonance scattering, treated in the Sobolev approximation. Synow does not do continuum transport, it does not solve rate equations, and it does not calculate ionization ratios. Its main function is to take line multiple scattering into account so that it can be used in an empirical spirit to make line identifications and estimate the velocity at the photosphere (or pseudo-photosphere) and the velocity interval within which each ion is detected. these quantities provide constraints on the composition structure of the ejected matter.

[ascl:1302.014]
SYNMAG Photometry: Catalog-level Matched Colors of Extended Sources

Bundy, Kevin; Hogg, David W.; Higgs, Tim D.; Nichol, Robert C.; Yasuda, Naoki; Masters, Karen L.; Lang, Dustin; Wake, David A.

SYNMAG is a tool for producing synthetic aperture magnitudes to enable fast matched photometry at the catalog level without reprocessing imaging data. Aperture magnitudes are the most widely tabulated flux measurements in survey catalogs; obtaining reliable, matched photometry for galaxies imaged by different observatories represents a key challenge in the era of wide-field surveys spanning more than several hundred square degrees. Methods such as flux fitting, profile fitting, and PSF homogenization followed by matched-aperture photometry are all computationally expensive. An alternative solution called "synthetic aperture photometry" exploits galaxy profile fits in one band to efficiently model the observed, point-spread-function-convolved light profile in other bands and predict the flux in arbitrarily sized apertures.

[ascl:1308.007]
SYNAPPS: Forward-modeling of supernova spectroscopy data sets

SYNAPPS is a spectrum fitter embedding a highly parameterized synthetic SN spectrum calculation within a parallel asynchronous optimizer. This open-source code is aimed primarily at the problem of systematically interpreting large sets of SN spectroscopy data.

[ascl:1308.008]
SYN++: Standalone SN spectrum synthesis

SYN++ is a standalone SN spectrum synthesis program. It is a rewrite of the original SYNOW (ascl:1010.055) code in modern C++. It offers further enhancements, a new structured input control file format, and the atomic data files have been repackaged and are more complete than those of SYNOW.

[ascl:1806.019]
SYGMA: Modeling stellar yields for galactic modeling

SYGMA (Stellar Yields for Galactic Modeling Applications) follows the ejecta of simple stellar populations as a function of time to model the enrichment and feedback from simple stellar populations. It is the basic building block of the galaxy code One-zone Model for the Evolution of GAlaxies (OMEGA, ascl:1806.018) and is part of the NuGrid Python Chemical Evolution Environment (NuPyCEE, ascl:1610.015). Stellar yields of AGB and massive stars are calculated with the same nuclear physics and are provided by the NuGrid collaboration.

[ascl:1904.001]
sxrbg: ROSAT X-Ray Background Tool

The ROSAT X-Ray Background Tool (sxrbg) calculates the average X-ray background count rate and statistical uncertainty in each of the six standard bands of the ROSAT All-Sky Survey (RASS) diffuse background maps (R1, R2, R4, R5, R6, R7) for a specified astronomical position and a search region consisting of either a circle with a specified radius or an annulus with specified inner and outer radii centered on the position. The values returned by the tool are in units of 10^-6 counts/second/arcminute^2. sxrbg can also create a count-rate-based spectrum file which can be used with XSpec (ascl:9910.005) to calculate fluxes and offers support for counts statistics (cstat), an alternative method for generating a background spectrum. HEASoft (ascl:1408.004) is a prerequisite for building. The code is in the public domain.

[ascl:1707.007]
swot: Super W Of Theta

SWOT (Super W Of Theta) computes two-point statistics for very large data sets, based on “divide and conquer” algorithms, mainly, but not limited to data storage in binary trees, approximation at large scale, parellelization (open MPI), and bootstrap and jackknife resampling methods “on the fly”. It currently supports projected and 3D galaxy auto and cross correlations, galaxy-galaxy lensing, and weighted histograms.

[ascl:1606.001]
SWOC: Spectral Wavelength Optimization Code

SWOC (Spectral Wavelength Optimization Code) determines the wavelength ranges that provide the optimal amount of information to achieve the required science goals for a spectroscopic study. It computes a figure-of-merit for different spectral configurations using a user-defined list of spectral features, and, utilizing a set of flux-calibrated spectra, determines the spectral regions showing the largest differences among the spectra.

[ascl:1112.018]
SwiftVis: Data Analysis & Visualization For Planetary Science

SwiftVis is a tool originally developed as part of a rewrite of Swift to be used for analysis and plotting of simulations performed with Swift and Swifter. The extensibility built into the design has allowed us to make SwiftVis a general purpose analysis and plotting package customized to be usable by the planetary science community at large. SwiftVis is written in Java and has been tested on Windows, Linux, and Mac platforms. Its graphical interface allows users to do complex analysis and plotting without having to write custom code.

[ascl:1805.020]
SWIFT: SPH With Inter-dependent Fine-grained Tasking

SWIFT runs cosmological simulations on peta-scale machines for solving gravity and SPH. It uses the Fast Multipole Method (FMM) to calculate gravitational forces between nearby particles, combining these with long-range forces provided by a mesh that captures both the periodic nature of the calculation and the expansion of the simulated universe. SWIFT currently uses a single fixed but time-variable softening length for all the particles. Many useful external potentials are also available, such as galaxy haloes or stratified boxes that are used in idealised problems. SWIFT implements a standard LCDM cosmology background expansion and solves the equations in a comoving frame; equations of state of dark-energy evolve with scale-factor. The structure of the code allows implementation for modified-gravity solvers or self-interacting dark matter schemes to be implemented. Many hydrodynamics schemes are implemented in SWIFT and the software allows users to add their own.

[ascl:1303.001]
SWIFT: A solar system integration software package

SWIFT follows the long-term dynamical evolution of a swarm of test particles in the solar system. The code efficiently and accurately handles close approaches between test particles and planets while retaining the powerful features of recently developed mixed variable symplectic integrators. Four integration techniques are included: Wisdom-Holman Mapping; Regularized Mixed Variable Symplectic (RMVS) method; fourth order T+U Symplectic (TU4) method; and Bulirsch-Stoer method. The package is designed so that the calls to each of these look identical so that it is trivial to replace one with another. Complex data manipulations and results can be analyzed with the graphics packace SwiftVis.

[ascl:1010.068]
SWarp: Resampling and Co-adding FITS Images Together

SWarp resamples and co-adds together FITS images using any arbitrary astrometric projection defined in the WCS standard. It operates on pre-reduced images and their weight-maps. Based on the astrometric and photometric calibrations derived at an earlier phase of the pipeline, SWarp re-maps ("warps") the pixels to a perfect projection system, and co-adds them in an optimum way, according to their relative weights. SWarp's astrometric engine is based on a customized version of Calabretta's WCSLib 2.6 and supports all of the projections defined in the 2000 version of the WCS proposal.

[ascl:1208.012]
Swarm-NG: Parallel n-body Integrations

Dindar, Saleh; Ford, Eric B.; Juric, Mario; Young, In Yeo; Gao, Jianwei; Boley, Aaron C.; Nelson, Benjamin; Peters, Jorg

Swarm-NG is a C++ library for the efficient direct integration of many n-body systems using highly-parallel Graphics Processing Units (GPU). Swarm-NG focuses on many few-body systems, e.g., thousands of systems with 3...15 bodies each, as is typical for the study of planetary systems; the code parallelizes the simulation, including both the numerical integration of the equations of motion and the evaluation of forces using NVIDIA's "Compute Unified Device Architecture" (CUDA) on the GPU. Swarm-NG includes optimized implementations of 4th order time-symmetrized Hermite integration and mixed variable symplectic integration as well as several sample codes for other algorithms to illustrate how non-CUDA-savvy users may themselves introduce customized integrators into the Swarm-NG framework. Applications of Swarm-NG include studying the late stages of planet formation, testing the stability of planetary systems and evaluating the goodness-of-fit between many planetary system models and observations of extrasolar planet host stars (e.g., radial velocity, astrometry, transit timing). While Swarm-NG focuses on the parallel integration of many planetary systems,the underlying integrators could be applied to a wide variety of problems that require repeatedly integrating a set of ordinary differential equations many times using different initial conditions and/or parameter values.

[ascl:1804.016]
surrkick: Black-hole kicks from numerical-relativity surrogate models

surrkick quickly and reliably extract recoils imparted to generic, precessing, black hole binaries. It uses a numerical-relativity surrogate model to obtain the gravitational waveform given a set of binary parameters, and from this waveform directly integrates the gravitational-wave linear momentum flux. This entirely bypasses the need of fitting formulae which are typically used to model black-hole recoils in astrophysical contexts.

[ascl:1605.017]
Surprise Calculator: Estimating relative entropy and Surprise between samples

The Surprise is a measure for consistency between posterior distributions and operates in parameter space. It can be used to analyze either the compatibility of separately analyzed posteriors from two datasets, or the posteriors from a Bayesian update. The Surprise Calculator estimates relative entropy and Surprise between two samples, assuming they are Gaussian. The software requires the R package CompQuadForm to estimate the significance of the Surprise, and rpy2 to interface R with Python.

[ascl:1809.007]
surfinBH: Surrogate final black hole properties for mergers of binary black holes

surfinBH predicts the final mass, spin and recoil velocity of the remnant of a binary black hole merger. Trained directly against numerical relativity simulations, these models are extremely accurate, reproducing the results of the simulations at the same level of accuracy as the simulations themselves. Fits such as these play a crucial role in waveform modeling and tests of general relativity with gravitational waves, performed by LIGO.

[ascl:1403.008]
SURF: Submm User Reduction Facility

SURF reduces data from the SCUBA instrument from the James Clerk Maxwell Telescope. Facilities are provided for reducing all the SCUBA observing modes including jiggle, scan and photometry modes. SURF uses the Starlink environment (ascl:1110.012).

[ascl:1612.015]
Superplot: Graphical interface for plotting and analyzing data

Superplot calculates and plots statistical quantities relevant to parameter inference from a "chain" of samples drawn from a parameter space produced by codes such as MultiNest (ascl:1109.006), BAYES-X (ascl:1505.027), and PolyChord (ascl:1502.011). It offers a graphical interface for browsing a chain of many variables quickly and can produce numerous kinds of publication quality plots, including one- and two-dimensional profile likelihood, three-dimensional scatter plots, and confidence intervals and credible regions. Superplot can also save plots in PDF format, create a summary text file, and export a plot as a pickled object for importing and manipulating in a Python interpreter.

[ascl:1705.017]
supernovae: Photometric classification of supernovae

Supernovae classifies supernovae using their light curves directly as inputs to a deep recurrent neural network, which learns information from the sequence of observations. Observational time and filter fluxes are used as inputs; since the inputs are agnostic, additional data such as host galaxy information can also be included.

[ascl:1109.014]
Supernova Flux-averaging Likelihood Code

Flux-averaging justifies the use of the distance-redshift relation for a smooth universe in the analysis of type Ia supernova (SN Ia) data. Flux-averaging of SN Ia data is required to yield cosmological parameter constraints that are free of the bias induced by weak gravitational lensing. SN Ia data are converted into flux. For a given cosmological model, the distance dependence of the data is removed, then the data are binned in redshift, and placed at the average redshift in each redshift bin. The likelihood of the given cosmological model is then computed using "flux statistics''. These Fortran codes compute the likelihood of an arbitrary cosmological model [with given H(z)/H_0] using flux-averaged Type Ia supernova data.

[ascl:1511.001]
SuperFreq: Numerical determination of fundamental frequencies of an orbit

SuperFreq numerically estimates the fundamental frequencies and orbital actions of pre-computed orbital time series. It is an implementation of a version of the Numerical Analysis of Fundamental Frequencies close to that by Monica Valluri, which itself is an implementation of an algorithm first used by Jacques Laskar.

[ascl:1507.002]
SUPERBOX: Particle-multi-mesh code to simulate galaxies

SUPERBOX is a particle-mesh code that uses moving sub-grids to track and resolve high-density peaks in the particle distribution and a nearest grid point force-calculation scheme based on the second derivatives of the potential. The code implements a fast low-storage FFT-algorithm and allows a highly resolved treatment of interactions in clusters of galaxies, such as high-velocity encounters between elliptical galaxies and the tidal disruption of dwarf galaxies, as sub-grids follow the trajectories of individual galaxies. SUPERBOX is efficient in that the computational overhead is kept as slim as possible and is also memory efficient since it uses only one set of grids to treat galaxies in succession.

[ascl:1609.019]
SuperBoL: Module for calculating the bolometric luminosities of supernovae

SuperBoL calculates the bolometric lightcurves of Type II supernovae using observed photometry; it includes three different methods for calculating the bolometric luminosity: quasi-bolometric, direct, and bolometric correction. SuperBoL propagates uncertainties in the input data through the calculations made by the code, allowing for error bars to be included in plots of the lightcurve.

[ascl:1109.007]
SuperBayeS: Supersymmetry Parameters Extraction Routines for Bayesian Statistics

SuperBayeS is a package for fast and efficient sampling of supersymmetric theories. It uses Bayesian techniques to explore multidimensional SUSY parameter spaces and to compare SUSY predictions with observable quantities, including sparticle masses, collider observables, dark matter abundance, direct detection cross sections, indirect detection quantities etc. Scanning can be performed using Markov Chain Monte Carlo (MCMC) technology or even more efficiently by employing a new scanning technique called, MultiNest. which implements the nested sampling algorithm. Using MultiNest, a full 8-dimensional scan of the CMSSM takes about 12 hours on 10 2.4GHz CPUs. There is also an option for old-style fixed-grid scanning. A discussion forum for SuperBayeS is available.

The package combines SoftSusy, DarkSusy, FeynHiggs, Bdecay, MultiNest and MicrOMEGAs. Some of the routines and the plotting tools are based on CosmoMC.

SuperBayeS comes with SuperEGO, a MATLAB graphical user interface tool for interactive plotting of the results. SuperEGO has been developed by Rachid Lemrani and is based on CosmoloGUI by Sarah Bridle.

[ascl:1105.007]
Sunspot Models

This IDL code creates a thick magneto-static structure with parameters of a typical sunspot in a solar like photosphere - chromosphere. The variable parameters are field strength on the axis, radius, and Wilson depression (displacement of the atmosphere on the axis with respect to the field-free atmosphere). Output are magnetic field vector, pressure and density distributions with radius and height. The structure has azimuthal symmetry. The codes are relatively self explanatory and the download packages contain README files.

[ascl:1303.030]
Sunrise: Radiation transfer through interstellar dust

Sunrise is a Monte Carlo radiation transfer code for calculating absorption and scattering of light to study the effects of dust in hydrodynamic simulations of interacting galaxies. It uses an adaptive mesh refinement grid to describe arbitrary geometries of emitting and absorbing/scattering media, with spatial dynamical range exceeding 10^{4}; it can efficiently generate images of the emerging radiation at arbitrary points in space and spectral energy distributions of simulated galaxies run with the Gadget, Gasoline, Arepo, Enzo or ART codes. In addition to the monochromatic radiative transfer typically used by Monte Carlo codes, Sunrise can propagate a range of wavelengths simultaneously. This "polychromatic" algorithm gives significant improvements in efficiency and accuracy when spectral features are calculated.

[ascl:1401.010]
SunPy: Python for Solar Physicists

SunPy is a community-developed free and open-source software package for solar physics and is an alternative to the SolarSoft data analysis environment. SunPy provides data structures for representing the most common solar data types (images, lightcurves, and spectra) and integration with the Virtual Solar Observatory (VSO) and the Heliophysics Event Knowledgebase (HEK) for data acquisition.

[ascl:1010.067]
Stuff: Simulating “Perfect” Astronomical Catalogues

Stuff is a program that simulates “perfect” astronomical catalogues. It generate object lists in ASCII which can read by the SkyMaker program to produce realistic astronomical fields. Stuff is part of the EFIGI development project.

[submitted]
stsynphot: synphot for HST and JWST

An extension to synphot (ascl:1811.001), stsynphot implements synthetic photometry package for HST and JWST support. The software constructs spectra from various grids of model atmosphere spectra, parameterized spectrum models, and atlases of stellar spectrophotometry. It also simulates observations specific to HST and JWST, computes photometric calibration parameters for any supported instrument mode, and plots instrument-specific sensitivity curves and calibration target spectra.

[ascl:1206.003]
STSDAS: IRAF Tools for Hubble Space Telescope data reduction

The Space Telescope Science Data Analysis System (STSDAS) is a software package for reducing and analyzing astronomical data. It is layered on top of IRAF and provides general-purpose tools for astronomical data analysis as well as routines specifically designed for HST data. In particular, STSDAS contains all the programs used for the calibration and reduction of HST data in the STScI post-observation processing pipelines.

[ascl:1106.021]
StringFast: Fast Code to Compute CMB Power Spectra induced by Cosmic Strings

StringFast implements a method for efficient computation of the C_l spectra induced by a network of strings, which is fast enough to be used in Markov Chain Monte Carlo analyses of future data. This code allows the user to calculate TT, EE, and BB power spectra (scalar [for TT and EE], vector, and tensor modes) for "wiggly" cosmic strings. StringFast uses the output of the public code CMBACT (ascl:1106.023). The properties of the strings are described by four parameters: Gμ—dimensionless string tension; v—rms transverse velocity (as fraction of c); α—"wiggliness"; ξ—comoving correlation length of the string network. It is written as a Fortran 90 module.

[ascl:1702.010]
streamgap-pepper: Effects of peppering streams with many small impacts

streamgap-pepper computes the effect of subhalo fly-bys on cold tidal streams based on the action-angle representation of streams. A line-of-parallel-angle approach is used to calculate the perturbed distribution function of a given stream segment by undoing the effect of all impacts. This approach allows one to compute the perturbed stream density and track in any coordinate system in minutes for realizations of the subhalo distribution down to 10^5 Msun, accounting for the stream's internal dispersion and overlapping impacts. This code uses galpy (ascl:1411.008) and the streampepperdf.py galpy extension, which implements the fast calculation of the perturbed stream structure.

[ascl:1702.009]
stream-stream: Stellar and dark-matter streams interactions

Stream-stream analyzes the interaction between a stellar stream and a disrupting dark-matter halo. It requires galpy (ascl:1411.008), NEMO (ascl:1010.051), and the usual common scientific Python packages.

[ascl:1708.005]
STools: IDL Tools for Spectroscopic Analysis

STools contains a variety of simple tools for spectroscopy, such as reading an IRAF-formatted (multispec) echelle spectrum in FITS, measuring the wavelength of the center of a line, Gaussian convolution, deriving synthetic photometry from an input spectrum, and extracting and interpolating a MARCS model atmosphere (standard composition).

[ascl:1204.009]
STOKES: Modeling Radiative Transfer and Polarization

STOKES was designed to perform three-dimensional radiative transfer simulations for astronomical applications. The code also considers the polarization properties of the radiation. The program is based on the Monte-Carlo method and treats optical and ultraviolet polarization induced by scattering off free electrons or dust grains. Emission and scattering regions can be arranged in various geometries within the model space, the computed continuum and line spectra can be evaluated at different inclinations and azimuthal viewing angles.

[ascl:1608.001]
Stingray: Spectral-timing software

Stingray is a spectral-timing software package for astrophysical X-ray (and more) data. The package merges existing efforts for a (spectral-)timing package in Python and is composed of a library of time series methods (including power spectra, cross spectra, covariance spectra, and lags); scripts to load FITS data files from different missions; a simulator of light curves and event lists that includes different kinds of variability and more complicated phenomena based on the impulse response of given physical events (e.g. reverberation); and a GUI to ease the learning curve for new users.

[ascl:1105.001]
STILTS: Starlink Tables Infrastructure Library Tool Set

The STIL Tool Set is a set of command-line tools based on STIL, the Starlink Tables Infrastructure Library. It deals with the processing of tabular data; the package has been designed for, but is not restricted to, astronomical tables such as object catalogues. Some of the tools are generic and can work with multiple formats (including FITS, VOTable, CSV, SQL and ASCII), and others are specific to the VOTable format. In some ways, STILTS forms the command-line counterpart of the GUI table analysis tool TOPCAT. The package is robust, fully documented, and designed for efficiency, especially with very large datasets.

Facilities offered include:

- format conversion
- crossmatching
- plotting
- column calculation and rearrangement
- row selections
- data and metadata manipulation and display
- sorting
- statistical calculations
- histogram calculation
- data validation
- VO service access

[ascl:1110.006]
STIFF: Converting Scientific FITS Images to TIFF

STIFF is a program that converts scientific FITS1 images to the more popular TIFF2 format for illustration purposes. Most FITS readers and converters do not do a proper job at converting FITS image data to 8 bits. 8-bit images stored in JPEG, PNG or TIFF files have the intensities implicitely stored in a non-linear way. Most current FITS image viewers and converters provide the user an incorrect translation of the FITS image content by simply rescaling linearly input pixel values. A first consequence is that the people working on astronomical images usually have to apply narrow intensity cuts or square-root or logarithmic intensity transformations to actually see something on their deep-sky images. A less obvious consequence is that colors obtained by combining images processed this way are not consistent across such a large range of surface brightnesses. Though with other software the user is generally afforded a choice of nonlinear transformations to apply in order to make the faint stuff stand out more clearly in the images, with the limited selection of choices provides, colors will not be accurately rendered, and some manual tweaking will be necessary. The purpose of STIFF is to produce beautiful pictures in an automatic and consistent way.

[ascl:1810.014]
STiC: Stockholm inversion code

STiC is a MPI-parallel non-LTE inversion code for observed full-Stokes observations. The code processes lines from multiple atoms in non-LTE, including partial redistribution effects of scattered photons in angle and frequency of scattered photons (PRD), and can be used with model atmospheres that have a complex depth stratification without introducing artifacts.

[submitted]
stginga: Ginga for STScI

stginga customizes Ginga to aid data analysis for the data supported by STScI (e.g., HST or JWST). For instance, it provides plugins and configuration files that understand HST and JWST data products.

[ascl:1306.009]
STF: Structure Finder

STF is a general structure finder designed to find halos, subhaloes, and tidal debris in N-body simulations. The current version is designed to read in "particle data" (that is SPH N-body data), but a simple modification of the I/O can have it read grid data from Grid based codes.

[ascl:1805.006]
StePS: Stereographically Projected Cosmological Simulations

StePS (Stereographically Projected Cosmological Simulations) compactifies the infinite spatial extent of the Universe into a finite sphere with isotropic boundary conditions to simulate the evolution of the large-scale structure. This eliminates the need for periodic boundary conditions, which are a numerical convenience unsupported by observation and which modifies the law of force on large scales in an unrealistic fashion. StePS uses stereographic projection for space compactification and naive O(N2) force calculation; this arrives at a correlation function of the same quality more quickly than standard (tree or P3M) algorithms with similar spatial and mass resolution. The N2 force calculation is easy to adapt to modern graphics cards, hence StePS can function as a high-speed prediction tool for modern large-scale surveys.

[ascl:1809.014]
stepped_luneburg: Stacked-based ray tracing code to model a stepped Luneburg lens

stepped_luneburg investigates the scattered light properties of a Luneburg lens approximated as a series of concentric shells with discrete refractive indices. The optical Luneburg lens has promising applications for low-cost, continuous all-sky monitoring to obtain transit light curves of bright, nearby stars. This code implements a stack-based algorithm that tracks all reflected and refracted rays generated at each optical interface of the lens as described by Snell's law. The Luneburg lens model parameters, such as number of lens layers, the power-law that describes the refractive indices, the number of incident rays, and the initial direction of the incident wavefront can be altered to optimize lens performance. The stepped_luneburg module can be imported within the Python environment or used with scripting, and it is accompanied by two other modules, enc_int and int_map, that help the user to determine the resolving power of the lens and the strength of scattered light haloes for the purpose of quality assessment.

[ascl:1901.012]
stellarWakes: Dark matter subhalo searches using stellar kinematic data

stellarWakes uses stellar kinematic data to search for dark matter (DM) subhalos through their gravitational perturbations to the stellar phase-space distribution.

[ascl:1303.028]
Stellarics: Inverse Compton scattering from stellar heliospheres

Cosmic ray electrons scatter on the photon fields around stars, including the sun, to create gamma rays by the inverse Compton effect. Stellarics computes the spectrum and angular distribution of this emission. The software also includes general-purpose routines for inverse Compton scattering on a given electron spectrum, for example for interstellar or astrophysical source modelling.

[ascl:1505.009]
StellaR: Stellar evolution tracks and isochrones tools

stellaR accesses and manipulates publicly available stellar evolutionary tracks and isochrones from the Pisa low-mass database. It retrieves and plots the required calculations from CDS, constructs by interpolation tracks or isochrones of compositions different to the ones available in the database, constructs isochrones for age not included in the database, and extracts relevant evolutionary points from tracks or isochrones.

[ascl:1108.013]
STELLA: Multi-group Radiation Hydrodynamics Code

STELLA is a one-dimensional multi-group radiation hydrodynamics code. STELLA incorporates implicit hydrodynamics coupled to a multi-group non-equilibrium radiative transfer for modeling SN II-L light curves. The non-equilibrium description of radiation is crucial for this problem since the presupernova envelope may be of low mass and very dilute. STELLA implicitly treats time dependent equations of the angular moments of intensity averaged over a frequency bin. Local thermodynamic equilibrium is assumed to determine the ionization levels of materials.

[ascl:1108.018]
STECKMAP: STEllar Content and Kinematics via Maximum A Posteriori likelihood

STECKMAP stands for STEllar Content and Kinematics via Maximum A Posteriori likelihood. It is a tool for interpreting galaxy spectra in terms of their stellar populations through the derivation of their star formation history, age-metallicity relation, kinematics and extinction. The observed spectrum is projected onto a temporal sequence of models of single stellar populations, so as to determine a linear combination of these models that best fits the observed spectrum. The weights of the various components of this linear combination indicate the stellar content of the population. This procedure is regularized using various penalizing functions. The principles of the method are detailed in Ocvirk et al. 2006.

[ascl:1206.006]
statpl: Goodness-of-fit for power-law distributed data

statpl estimates the parameter of power-law distributed data and calculates goodness-of-fit tests for them. Many objects studied in astronomy follow a power-law distribution function (DF), for example the masses of stars or star clusters. Such data is often analyzed by generating a histogram and fitting a straight line to it. The parameters obtained in this way can be severely biased, and the properties of the underlying DF, such as its shape or a possible upper limit, are difficult to extract. statpl is an (effectively) bias-free estimator for the exponent and the upper limit.

[ascl:1704.004]
STATCONT: Statistical continuum level determination method for line-rich sources

STATCONT determines the continuum emission level in line-rich spectral data by inspecting the intensity distribution of a given spectrum by using different statistical approaches. The sigma-clipping algorithm provides the most accurate continuum level determination, together with information on the uncertainty in its determination; this uncertainty is used to correct the final continuum emission level. In general, STATCONT obtains accuracies of < 10 % in the continuum determination, and < 5 % in most cases. The main products of the software are the continuum emission level, together with its uncertainty, and data cubes containing only spectral line emission, i.e. continuum-subtracted data cubes. STATCONT also includes the option to estimate the spectral index or variation of the continuum emission with frequency.

[ascl:1805.010]
StarSmasher: Smoothed Particle Hydrodynamics code for smashing stars and planets

Smoothed Particle Hydrodynamics (SPH) is a Lagrangian particle method that approximates a continuous fluid as discrete nodes, each carrying various parameters such as mass, position, velocity, pressure, and temperature. In an SPH simulation the resolution scales with the particle density; StarSmasher is able to handle both equal-mass and equal number-density particle models. StarSmasher solves for hydro forces by calculating the pressure for each particle as a function of the particle's properties - density, internal energy, and internal properties (e.g. temperature and mean molecular weight). The code implements variational equations of motion and libraries to calculate the gravitational forces between particles using direct summation on NVIDIA graphics cards. Using a direct summation instead of a tree-based algorithm for gravity increases the accuracy of the gravity calculations at the cost of speed. The code uses a cubic spline for the smoothing kernel and an artificial viscosity prescription coupled with a Balsara Switch to prevent unphysical interparticle penetration. The code also implements an artificial relaxation force to the equations of motion to add a drag term to the calculated accelerations during relaxation integrations. Initially called StarCrash, StarSmasher was developed originally by Rasio.

[ascl:1703.005]
starsense_algorithms: Performance evaluation of various star sensors

Sarpotdar, Mayuresh; Mathew, Joice; Sreejith, A. G.; Nirmal, K.; Ambily, S.; Prakash, Ajin; Safonova, Margarita; Murthy, Jayant

The Matlab starsense_algorithms package evaluates the performance of various star sensors through the implementation of centroiding, geometric voting and QUEST algorithms. The physical parameters of a star sensor are parametrized and by changing these parameters, performance estimators such as sky coverage, memory requirement, and timing requirements can be estimated for the selected star sensor.

[ascl:1107.008]
STARS: A Stellar Evolution Code

Eggleton, P. P.; Tout, Christopher; Pols, Onno; Izzard, Rob; Eldridge, John; Lesaffre, Pierre; Stancliffe, Richard; Church, Ross; Lau, Herbert

We have developed a detailed stellar evolution code capable of following the simultaneous evolution of both stars in a binary system, together with their orbital properties. To demonstrate the capabilities of the code we investigate potential progenitors for the Type IIb supernova 1993J, which is believed to have been an interacting binary system prior to its primary exploding. We use our detailed binary stellar evolution code to model this system to determine the possible range of primary and secondary masses that could have produced the observed characteristics of this system, with particular reference to the secondary. Using the luminosities and temperatures for both stars (as determined by Maund et al. 2004) and the remaining mass of the hydrogen envelope of the primary at the time of explosion, we find that if mass transfer is 100 per cent efficient the observations can be reproduced by a system consisting of a 15 solar mass primary and a 14 solar mass secondary in an orbit with an initial period of 2100 days. With a mass transfer efficiency of 50 per cent, a more massive system consisting of a 17 solar mass primary and a 16 solar mass secondary in an initial orbit of 2360 days is needed. We also investigate some of the uncertainties in the evolution, including the effects of tidal interaction, convective overshooting and thermohaline mixing.

[ascl:1810.005]
STARRY: Analytic computation of occultation light curves

Luger, Rodrigo; Agol, Eric; Foreman-Mackey, Daniel; Fleming, David P.; Lustig-Yaeger, Jacob; Deitrick, Russell

STARRY computes light curves for various applications in astronomy: transits and secondary eclipses of exoplanets, light curves of eclipsing binaries, rotational phase curves of exoplanets, light curves of planet-planet and planet-moon occultations, and more. By modeling celestial body surface maps as sums of spherical harmonics, STARRY does all this analytically and is therefore fast, stable, and differentiable. Coded in C++ but wrapped in Python, STARRY is easy to install and use.

[ascl:1609.002]
StarPy: Quenched star formation history parameters of a galaxy using MCMC

Smethurst, R. J.; Lintott, C. J.; Simmons, B. D.; Schawinski, K.; Marshall, P. J.; Bamford, S.; Fortson, L.; Kaviraj, S.; Masters, K. L.; Melvin, T.; Nichol, R. C.; Skibba, R. A.; Willett, K. W.

StarPy derives the quenching star formation history (SFH) of a single galaxy through the Bayesian Markov Chain Monte Carlo method code *emcee* (ascl:1303.002). The sample function implements the emcee EnsembleSampler function for the galaxy colors input. Burn-in is run and calculated for the length specified before the sampler is reset and then run for the length of steps specified. StarPy provides the ability to use the look-up tables provided or creating your own.

[ascl:1406.020]
STARMAN: Stellar photometry and image/table handling

STARMAN is a stellar photometry package designed for the reduction of data from imaging systems. Its main components are crowded-field photometry programs, aperture photometry programs, a star finding program, and a CCD reduction program.

Image and table handling are served by a large number of programs which have a general use in photometry and other types of work. The package is a coherent whole, for use in the entire process of stellar photometry from raw images to the final standard-system magnitudes and their plotting as color-magnitude and color-color diagrams. It was distributed as part of the Starlink software collection (ascl:1110.012).

[ascl:1110.012]
Starlink: Multi-purpose Astronomy Software

Starlink has many applications within it to meet a variety of needs; it includes:

- a general astronomical image viewer;
- data reduction tools, including programs for reducing CCD-like data;
- general-purpose data-analysis and visualisation tools;
- image processing, data visualisation, and manipulating NDF components;
- a flexible and powerful library for handling World Coordinate Systems (partly based on the SLALIB library);
- a library of routines intended to make accurate and reliable positional-astronomy applications easier to write; and
- and a Hierarchical Data System that is portable and flexible for storing and retrieving data.

[ascl:1411.022]
Starlink Figaro: Starlink version of the Figaro data reduction software package

Shortridge, Keith; Meyerdierks, Horst; Currie, Malcolm J.; Davenhall, Clive; Jenness, Tim; Clayton, Martin

Starlink Figaro is an independently-maintained fork of Figaro (ascl:1203.013) that runs in the Starlink software environment (ascl:1110.012). It is a general-purpose data reduction package targeted mainly at optical/IR spectroscopy. It uses the NDF data format and the ADAM libraries for parameters and messaging.

[ascl:1108.006]
STARLIGHT: Spectral Synthesis Code

The study of stellar populations in galaxies is entering a new era with the availability of large and high quality databases of both observed galactic spectra and state-of-the-art evolutionary synthesis models. The power of spectral synthesis can be investigated as a mean to estimate physical properties of galaxies. Spectral synthesis is nothing more than the decomposition of an observed spectrum in terms of a superposition of a base of simple stellar populations of various ages and metallicities, producing astrophysically interesting output such as the star-formation and chemical enrichment histories of a galaxy, its extinction and velocity dispersion. This is what the STARLIGHT spectral synthesis code does.

[ascl:1010.076]
Starlab: A Software Environment for Collisional Stellar Dynamics

Traditionally, a simulation of a dense stellar system required choosing an initial model, running an integrator, and analyzing the output. Almost all of the effort went into writing a clever integrator that could handle binaries, triples and encounters between various multiple systems efficiently. Recently, the scope and complexity of these simulations has increased dramatically, for three reasons: 1) the sheer size of the data sets, measured in Terabytes, make traditional 'awking and grepping' of a single output file impractical; 2) the addition of stellar evolution data brings qualitatively new challenges to the data reduction; 3) increased realism of the simulations invites realistic forms of 'SOS': Simulations of Observations of Simulations, to be compared directly with observations. We are now witnessing a shift toward the construction of archives as well as tailored forms of visualization including the use of virtual reality simulators and planetarium domes, and a coupling of both with budding efforts in constructing virtual observatories. This review describes these new trends, presenting Starlab as the first example of a full software environment for realistic large-scale simulations of dense stellar systems.

[ascl:1505.007]
Starfish: Robust spectroscopic inference tools

Starfish is a set of tools used for spectroscopic inference. It robustly determines stellar parameters using high resolution spectral models and uses Markov Chain Monte Carlo (MCMC) to explore the full posterior probability distribution of the stellar parameters. Additional potential applications include other types of spectra, such as unresolved stellar clusters or supernovae spectra.

[ascl:1204.008]
StarFISH: For Inferring Star-formation Histories

StarFISH is a suite of programs designed to determine the star formation history (SFH) of a stellar population, given multicolor stellar photometry and a library of theoretical isochrones. It constructs a library of synthetic color-magnitude diagrams from the isochrones, which includes the effects of extinction, photometric errors and completeness, and binarity. A minimization routine is then used to determine the linear combination of synthetic CMDs that best matches the observed photometry. The set of amplitudes modulating each synthetic CMD describes the star formation history of the observed stellar population.

[ascl:0011.001]
StarFinder: A code for stellar field analysis

Diolaiti, Emiliano; Bendinelli, Orazio; Bonaccini, Domenico; Close, Laird M.; Currie, Doug G.; Parmeggiani, Gianluigi

StarFinder is an IDL code for the deep analysis of stellar fields, designed for Adaptive Optics well-sampled images with high and low Strehl ratio. The Point Spread Function is extracted directly from the frame, to take into account the actual structure of the instrumental response and the atmospheric effects. The code is written in IDL language and organized in the form of a self-contained widget-based application, provided with a series of tools for data visualization and analysis. A description of the method and some applications to Adaptive Optics data are presented.

[ascl:1010.074]
StarCrash: 3-d Evolution of Self-gravitating Fluid Systems

StarCrash is a parallel fortran code based on Smoothed Particle Hydrodynamics (SPH) techniques to calculate the 3-d evolution of self-gravitating fluid systems. The code in particularly suited to the study of stellar interactions, such as mergers of binary star systems and stellar collisions. The StarCrash code comes with several important features, including:

- Several routines which construct the initial conditions appropriate to a wide variety of physical systems

- An efficient parallel neighbor-finding algorithm for calculating hydrodynamic quantities

- A parallel gravitational field solver based on FFT convolution techniques, which uses the FFTW software libraries

- Relaxation Techniques for single stars and synchronized binaries

- Three different artificial viscosity treatments to calculate the thermodynamic evolution of the matter

- An optional gravitational radiation back-reaction treatment, which calculates the damping force from gravity wave losses to lowest relativistic order in a spatially accurate way

[ascl:1104.003]
Starburst99: Synthesis Models for Galaxies with Active Star Formation

Leitherer, Claus; Schaerer, Daniel; Goldader, Jeff; Gonzalez-Delgado, Rosa; Robert, Carmelle; Foo Kune, Denis; de Mello, Duilia; Devost, Daniel; Heckman, Timothy M.; Aloisi, Alessandra; Martins, Lucimara; Vazquez, Gerardo

Starburst99 is a comprehensive set of model predictions for spectrophotometric and related properties of galaxies with active star formation. The models are presented in a homogeneous way for five metallicities between Z = 0.040 and 0.001 and three choices of the initial mass function. The age coverage is 10^6 to 10^9 yr. Spectral energy distributions are used to compute colors and other quantities.

[ascl:1805.009]
STARBLADE: STar and Artefact Removal with a Bayesian Lightweight Algorithm from Diffuse Emission

STARBLADE (STar and Artefact Removal with a Bayesian Lightweight Algorithm from Diffuse Emission) separates superimposed point-like sources from a diffuse background by imposing physically motivated models as prior knowledge. The algorithm can also be used on noisy and convolved data, though performing a proper reconstruction including a deconvolution prior to the application of the algorithm is advised; the algorithm could also be used within a denoising imaging method. STARBLADE learns the correlation structure of the diffuse emission and takes it into account to determine the occurrence and strength of a superimposed point source.

[ascl:1111.010]
Starbase Data Tables: An ASCII Relational Database for Unix

Database management is an increasingly important part of astronomical data analysis. Astronomers need easy and convenient ways of storing, editing, filtering, and retrieving data about data. Commercial databases do not provide good solutions for many of the everyday and informal types of database access astronomers need. The Starbase database system with simple data file formatting rules and command line data operators has been created to answer this need. The system includes a complete set of relational and set operators, fast search/index and sorting operators, and many formatting and I/O operators. Special features are included to enhance the usefulness of the database when manipulating astronomical data. The software runs under UNIX, MSDOS and IRAF.

[ascl:1801.003]
Stan: Statistical inference

Stan facilitates statistical inference at the frontiers of applied statistics and provides both a modeling language for specifying complex statistical models and a library of statistical algorithms for computing inferences with those models. These components are exposed through interfaces in environments such as R, Python, and the command line.

[ascl:1105.012]
Stagger: MHD Method for Modeling Star Formation

Stagger is an astrophysical MHD code actively used to model star formation. It is equipped with a multi-frequency radiative transfer module and a comprehensive equation of state module that includes a large number of atomic and molecular species, to be able to compute realistic 3-D models of the near-surface layers of stars. The current version of the code allows a discretization that explicitly conserves mass, momentum, energy, and magnetic flux. The tensor formulation of the viscosity ensures that the viscous force is insensitive to the coordinate system orientation, thereby avoiding artificial grid-alignment.

[ascl:1901.006]
ssos: Solar system objects detection pipeline

The ssos pipeline detects and identifies known and unknown Solar System Objects (SSOs) in astronomical images. ssos requires at least 3 images with overlapping field-of-views in the sky taken within a reasonable amount of time (*e.g.*, 2 hours, 1 night). SSOs are detected mainly by judging the apparent motion of all sources in the images. The pipeline serves as a wrapper for the SExtractor (ascl:1010.064) and SCAMP (ascl:1010.063) software suites and allows different source extraction strategies to be chosen. All sources in the images are subject to a highly configurable filter pipeline. ssos is a versatile, light-weight, and easy-to-use software for surveys or PI-observation campaigns lacking a dedicated SSO detection pipeline.

[ascl:1807.032]
SSMM: Slotted Symbolic Markov Modeling for classifying variable star signatures

SSMM (Slotted Symbolic Markov Modeling) reduces time-domain stellar variable observations to classify stellar variables. The method can be applied to both folded and unfolded data, and does not require time-warping for waveform alignment. Written in Matlab, the performance of the supervised classification code is quantifiable and consistent, and the rate at which new data is processed is dependent only on the computational processing power available.

[ascl:1303.015]
SSE: Single Star Evolution

SSE is a rapid single-star evolution (SSE) code; these analytical formulae cover all phases of evolution from the zero-age main-sequence up to and including remnant phases. It is valid for masses in the range 0.1-100 Msun and metallicity can be varied. The SSE package contains a prescription for mass loss by stellar winds. It also follows the evolution of rotational angular momentum for the star.

[ascl:1705.005]
SPTCLASS: SPecTral CLASSificator code

SPTCLASS assigns semi-automatic spectral types to a sample of stars. The main code includes three spectral classification schemes: the first one is optimized to classify stars in the mass range of TTS (K5 or later, hereafter LATE-type scheme); the second one is optimized to classify stars in the mass range of IMTTS (F late to K early, hereafter Gtype scheme), and the third one is optimized to classify stars in the mass range of HAeBe (F5 or earlier, hereafter HAeBe scheme). SPTCLASS has an interactive module that allows the user to select the best result from the three schemes and analyze the input spectra.

[ascl:1411.025]
SPT Lensing Likelihood: South Pole Telescope CMB lensing likelihood code

The SPT lensing likelihood code, written in Fortran90, performs a Gaussian likelihood based upon the lensing potential power spectrum using a file from CAMB (ascl:1102.026) which contains the normalization required to get the power spectrum that the likelihood call is expecting.

[ascl:1201.013]
SPS: SPIRE Photometer Simulator

The SPS software simulates the operation of the Spectral and Photometric Imaging Receiver on-board the ESA’s Herschel Space Observatory. It is coded using the Interactive Data Language (IDL), and produces simulated data at the level-0 stage (non-calibrated data in digitised units). The primary uses for the simulator are to:

- optimize and characterize the photometer observing functions
- aid in the development, validation, and characterization of the SPIRE data pipeline
- provide a realistic example of SPIRE data, and thus to facilitate the development of specific analysis tools for specific science cases.

[ascl:1806.013]
SpS: Single-pulse Searcher

The presence of human-made interference mimicking the behavior of celestial radio pulses is a major challenge when searching for radio pulses emitted on millisecond timescales by celestial radio sources such as pulsars and fast radio bursts due to the highly imbalanced samples. Single-pulse Searcher (SpS) reduces the presence of radio interference when processing standard output from radio single-pulse searches to produce diagnostic plots useful for selecting good candidates. The modular software allows modifications for specific search characteristics. LOTAAS Single-pulse Searcher (L-SpS) is an implementation of different features of the software (such as a machine-learning approach) developed for a particular study: the LOFAR Tied-Array All-Sky Survey (LOTAAS).

[ascl:1506.008]
SPRITE: Sparsity-based super-resolution algorithm

SPRITE (Sparse Recovery of InstrumenTal rEsponse) computes a well-resolved compact source image from several undersampled and noisy observations. The algorithm is based on sparse regularization; adding a sparse penalty in the recovery leads to far better accuracy in terms of ellipticity error, especially at low S/N.

[ascl:1411.015]
SPOTROD: Semi-analytic model for transits of spotted stars

SPOTROD is a model for planetary transits of stars with an arbitrary limb darkening law and a number of homogeneous, circular spots on their surface. It facilitates analysis of anomalies due to starspot eclipses, and is a free, open source implementation written in C with a Python API.

[ascl:1809.006]
spops: Spinning black-hole binary population synthesis

Gerosa, Davide; Berti, Emanuele; O'Shaughnessy, Richard; Belczynski, Krzysztof; Kesden, Michael; Wysocki, Daniel; Gladysz, Wojciech

spops is a database of populations synthesis simulations of spinning black-hole binary systems, together with a python module to query it. Data are obtained with the startrack and precession [ascl:1611.004] numerical codes to consistently evolve binary stars from formation to gravitational-wave detection. spops allows quick exploration of the interplay between stellar physics and black-hole spin dynamics.

[ascl:1103.005]
Splotch: Ray Tracer to Visualize SPH Simulations

Splotch is a light and fast, publicly available, ray-tracer software tool which supports the effective visualization of cosmological simulations data. The algorithm it relies on is designed to deal with point-like data, optimizing the ray-tracing calculation by ordering the particles as a function of their 'depth', defined as a function of one of the coordinates or other associated parameters. Realistic three-dimensional impressions are reached through a composition of the final colour in each pixel properly calculating emission and absorption of individual volume elements.

[ascl:1402.007]
SPLAT: Spectral Analysis Tool

SPLAT is a graphical tool for displaying, comparing, modifying and analyzing astronomical spectra stored in NDF, FITS and TEXT files as well as in NDX format. It can read in many spectra at the same time and then display these as line plots. Display windows can show one or several spectra at the same time and can be interactively zoomed and scrolled, centered on specific wavelengths, provide continuous coordinate readout, produce printable hardcopy and be configured in many ways. Analysis facilities include the fitting of a polynomial to selected parts of a spectrum, the fitting of Gaussian, Lorentzian and Voigt profiles to emission and absorption lines and the filtering of spectra using average, median and line-shape window functions as well as wavelet denoising. SPLAT also supports a full range of coordinate systems for spectra, which allows coordinates to be displayed and aligned in many different coordinate systems (wavelength, frequency, energy, velocity) and transformed between these and different standards of rest (topocentric, heliocentric, dynamic and kinematic local standards of rest, etc). SPLAT is distributed as part of the Starlink (ascl:1110.012) software collection.

[ascl:1402.008]
SPLAT-VO: Spectral Analysis Tool for the Virtual Observatory

SPLAT-VO is an extension of the SPLAT (Spectral Analysis Tool, ascl:1402.007) graphical tool for displaying, comparing, modifying and analyzing astronomical spectra; it includes facilities that allow it to work as part of the Virtual Observatory (VO). SPLAT-VO comes in two different forms, one for querying and downloading spectra from SSAP servers and one for interoperating with VO tools, such as TOPCAT (ascl:1101.010).

[ascl:1103.004]
SPLASH: Interactive Visualization Tool for Smoothed Particle Hydrodynamics Simulations

SPLASH (formerly SUPERSPHPLOT) visualizes output from (astrophysical) simulations using the Smoothed Particle Hydrodynamics (SPH) method in one, two and three dimensions. Written in Fortran 90, it uses the PGPLOT graphics subroutine library for plotting. It is based around a command-line menu structure but utilizes the interactive capabilities of PGPLOT to manipulate data interactively in the plotting window. SPLASH is fully interactive; visualizations can be changed rapidly at the touch of a button (e.g. zooming, rotating, shifting cross section positions etc). Data is read directly from the code dump format giving rapid access to results and the visualization is advanced forwards and backwards through timesteps by single keystrokes. SPLASH uses the SPH kernel to render plots of not only density but other physical quantities, giving a smooth representation of the data.

[ascl:1512.015]
Spirality: Spiral arm pitch angle measurement

Shields, Douglas W.; Boe, Benjamin; Pfountz, Casey; Davis, Benjamin L.; Hartley, Matthew; Pour Imani, Hamed; Slade, Zac; Kennefick, Daniel; Kennefick, Julia

Spirality measures spiral arm pitch angles by fitting galaxy images to spiral templates of known pitch. Written in MATLAB, the code package also includes GenSpiral, which produces FITS images of synthetic spirals, and SpiralArmCount, which uses a one-dimensional Fast Fourier Transform to count the spiral arms of a galaxy after its pitch is determined.

[ascl:1710.004]
SPIPS: Spectro-Photo-Interferometry of Pulsating Stars

SPIPS (Spectro-Photo-Interferometry of Pulsating Stars) combines radial velocimetry, interferometry, and photometry to estimate physical parameters of pulsating stars, including presence of infrared excess, color excess, Teff, and ratio distance/p-factor. The global model-based parallax-of-pulsation method is implemented in Python. Derived parameters have a high level of confidence; statistical precision is improved (compared to other methods) due to the large number of data taken into account, accuracy is improved by using consistent physical modeling and reliability of the derived parameters is strengthened by redundancy in the data.

[ascl:1608.020]
SPIDERz: SuPport vector classification for IDEntifying Redshifts

SPIDERz (SuPport vector classification for IDEntifying Redshifts) applies powerful support vector machine (SVM) optimization and statistical learning techniques to custom data sets to obtain accurate photometric redshift (photo-z) estimations. It is written for the IDL environment and can be applied to traditional data sets consisting of photometric band magnitudes, or alternatively to data sets with additional galaxy parameters (such as shape information) to investigate potential correlations between the extra galaxy parameters and redshift.

[ascl:1711.019]
SPIDERMAN: Fast code to simulate secondary transits and phase curves

SPIDERMAN calculates exoplanet phase curves and secondary eclipses with arbitrary surface brightness distributions in two dimensions. The code uses a geometrical algorithm to solve exactly the area of sections of the disc of the planet that are occulted by the star. Approximately 1000 models can be generated per second in typical use, which makes making Markov Chain Monte Carlo analyses practicable. The code is modular and allows comparison of the effect of multiple different brightness distributions for a dataset.

[ascl:1903.016]
SpiceyPy: Python wrapper for the NAIF C SPICE Toolkit

Annex, Andrew; Carcich, Brian; Murakami, Shin-ya; Kulumani, Shankar; de Val-Borro, Miguel; Stefko, Marcel; Diaz del Rio, Jorge; Seignovert, B.

SpiceyPy is a Python wrapper for the NAIF C SPICE Toolkit (ascl:1903.015). It is compatible with Python 2 and 3, and was written using ctypes.

[ascl:1903.015]
SPICE: Observation Geometry System for Space Science Missions

The SPICE (Spacecraft Planet Instrument C-matrix [“Camera matrix”] Events) toolkit offers a set of building blocks for constructing tools supporting multi-mission, international space exploration programs and research in planetary science, heliophysics, Earth science, and for observations from terrestrial observatories. It computes many kinds of observation geometry parameters, including the ephemerides, orientations, sizes, and shapes of planets, satellites, comets and asteroids. It can also compute the orientation of a spacecraft, its various moving structures, and an instrument's field-of-view location on a planet's surface or atmosphere. It can determine when a specified geometric event occurs, such as when an object is in shadow or is in transit across another object. The SPICE toolkit is available in FORTRAN 77, ANSI C, IDL, and MATLAB.

[ascl:1709.001]
SPHYNX: SPH hydrocode for subsonic hydrodynamical instabilities and strong shocks

SPHYNX addresses subsonic hydrodynamical instabilities and strong shocks; it is Newtonian, grounded on the Euler-Lagrange formulation of the smoothed-particle hydrodynamics technique, and density based. SPHYNX uses an integral approach for estimating gradients, a flexible family of interpolators to suppress pairing instability, and incorporates volume elements to provides better partition of the unity.

[ascl:1103.009]
SPHRAY: A Smoothed Particle Hydrodynamics Ray Tracer for Radiative Transfer

SPHRAY, a Smoothed Particle Hydrodynamics (SPH) ray tracer, is designed to solve the 3D, time dependent, radiative transfer (RT) equations for arbitrary density fields. The SPH nature of SPHRAY makes the incorporation of separate hydrodynamics and gravity solvers very natural. SPHRAY relies on a Monte Carlo (MC) ray tracing scheme that does not interpolate the SPH particles onto a grid but instead integrates directly through the SPH kernels. Given initial conditions and a description of the sources of ionizing radiation, the code will calculate the non-equilibrium ionization state (HI, HII, HeI, HeII, HeIII, e) and temperature (internal energy/entropy) of each SPH particle. The sources of radiation can include point like objects, diffuse recombination radiation, and a background field from outside the computational volume. The MC ray tracing implementation allows for the quick introduction of new physics and is parallelization friendly. A quick Axis Aligned Bounding Box (AABB) test taken from computer graphics applications allows for the acceleration of the raytracing component. We present the algorithms used in SPHRAY and verify the code by performing all the test problems detailed in the recent Radiative Transfer Comparison Project of Iliev et. al. The Fortran 90 source code for SPHRAY and example SPH density fields are made available online.

[ascl:1502.012]
SPHGR: Smoothed-Particle Hydrodynamics Galaxy Reduction

SPHGR (Smoothed-Particle Hydrodynamics Galaxy Reduction) is a python based open-source framework for analyzing smoothed-particle hydrodynamic simulations. Its basic form can run a baryonic group finder to identify galaxies and a halo finder to identify dark matter halos; it can also assign said galaxies to their respective halos, calculate halo & galaxy global properties, and iterate through previous time steps to identify the most-massive progenitors of each halo and galaxy. Data about each individual halo and galaxy is collated and easy to access.

SPHGR supports a wide range of simulations types including N-body, full cosmological volumes, and zoom-in runs. Support for multiple SPH code outputs is provided by pyGadgetReader (ascl:1411.001), mainly Gadget (ascl:0003.001) and TIPSY (ascl:1111.015).

[ascl:1311.005]
Spheroid: Electromagnetic Scattering by Spheroids

Spheroid determines the size distribution of polarizing interstellar dust grains based on electromagnetic scattering by spheroidal particles. It contains subroutines to treat the case of complex refractive indices, and also includes checks for some limiting cases.

[ascl:1309.004]
Spherical: Geometry operations and searches on spherical surfaces

The Spherical Library provides an efficient and accurate mathematical representation of shapes on the celestial sphere, such as sky coverage and footprints. Shapes of arbitrary complexity and size can be dynamically created from simple building blocks, whose exact area is also analytically computed. This methodology is also perfectly suited for censoring problematic parts of datasets, e.g., bad seeing, satellite trails or diffraction spikes of bright stars.

[ascl:1806.023]
Spheral++: Coupled hydrodynamical and gravitational numerical simulations

Spheral++ provides a steerable parallel environment for performing coupled hydrodynamical and gravitational numerical simulations. Hydrodynamics and gravity are modeled using particle-based methods (SPH and N-Body). It uses an Adaptive Smoothed Particle Hydrodynamics (ASPH) algorithm, provides a total energy conserving compatible hydro mode, and performs fluid and solid material modeling and damage and fracture modeling in solids.

[ascl:9912.001]
SPH_1D: Hierarchical gravity/SPH treecode for simulations of interacting galaxies

We describe a fast tree algorithm for gravitational N-body simulation on SIMD parallel computers. The tree construction uses fast, parallel sorts. The sorted lists are recursively divided along their x, y and z coordinates. This data structure is a completely balanced tree (i.e., each particle is paired with exactly one other particle) and maintains good spatial locality. An implementation of this tree-building algorithm on a 16k processor Maspar MP-1 performs well and constitutes only a small fraction (approximately 15%) of the entire cycle of finding the accelerations. Each node in the tree is treated as a monopole. The tree search and the summation of accelerations also perform well. During the tree search, node data that is needed from another processor is simply fetched. Roughly 55% of the tree search time is spent in communications between processors. We apply the code to two problems of astrophysical interest. The first is a simulation of the close passage of two gravitationally, interacting, disk galaxies using 65,636 particles. We also simulate the formation of structure in an expanding, model universe using 1,048,576 particles. Our code attains speeds comparable to one head of a Cray Y-MP, so single instruction, multiple data (SIMD) type computers can be used for these simulations. The cost/performance ratio for SIMD machines like the Maspar MP-1 make them an extremely attractive alternative to either vector processors or large multiple instruction, multiple data (MIMD) type parallel computers. With further optimizations (e.g., more careful load balancing), speeds in excess of today's vector processing computers should be possible.

[ascl:1404.017]
Spextool: Spectral EXtraction tool

Spextool (Spectral EXtraction tool) is an IDL-based data reduction package for SpeX, a medium resolution near-infrared spectrograph on the NASA IRTF. It performs all of the steps necessary to produce spectra ready for analysis and publication including non-linearity corrections, flat fielding, wavelength calibration, telluric correction, flux calibration, and order merging.

[ascl:1308.014]
SPEX: High-resolution cosmic X-ray spectra analysis

SPEX is optimized for the analysis and interpretation of high-resolution cosmic X-ray spectra. The software is especially suited for fitting spectra obtained by current X-ray observatories like XMM-Newton, Chandra, and Suzaku. SPEX can fit multiple spectra with different model components simultaneously and handles highly complex models with many free parameters.

[ascl:1807.014]
SPEGID: Single-Pulse Event Group IDentification

SPEGID (Single-Pulse Event Group IDentification) identifies astrophysical pulse candidates as trial single-pulse event groups (SPEGs) by first applying Density Based Spatial Clustering of Applications with Noise (DBSCAN) on trial single-pulse events and then merging the clusters that fall within the expected DM (Dispersion Measure) and time span of astrophysical pulses. SPEGID also calculates the peak score for each SPEG in the S/N versus DM space to identify the expected peak-like shape in the signal-to-noise (S/N) ratio versus DM curve of astrophysical pulses. Additionally, SPEGID groups SPEGs that appear at a consistent DM and therefore are likely emitted from the same source. After running SPEGID, periocity.py can be used to find (or verify) the underlying periodicity among a group of SPEGs (i.e., astrophysical pulse candidates).

[ascl:1310.008]
SPECX: Spectral Line Data Reduction Package

SPECX is a general purpose line data reduction system. It can read and write FITS data cubes but has specialist support for the GSD format data from the James Clerk Maxwell Telescope. It includes commands to store and retrieve intermediate spectra in storage registers and perform the fitting and removal of polynomial, harmonic and Gaussian baselines.

SPECX can filter and edit spectra and list and display spectra on a graphics terminal. It is able to perform Fourier transform and power spectrum calculations, process up to eight spectra (quadrants) simultaneously with either the same or different center, and assemble a number of reduced individual spectra into a map file and contour or greyscale any plane or planes of the resulting cube.

Two versions of SPECX are distributed. Version 6.x is the VMS and Unix version and is distributed as part of the Starlink software collection. Version 7.x is a complete rewrite of SPECX distributed for Windows.

[ascl:1902.011]
SpecViz: 1D Spectral Visualization Tool

SpecViz interactively visualizes and analyzes 1D astronomical spectra. It reads data from FITS and ASCII tables and allows spectra to be easily plotted and examined. It supports instrument-specific data quality handling, flexible spectral units conversions, custom plotting attributes, plot annotations, tiled plots, among other features. SpecViz includes a measurement tool for spectral lines for performing and recording measurements and a model fitting capability for creating simple (e.g., single Gaussian) or multi-component models (e.g., multiple Gaussians for emission and absorption lines in addition to regions of flat continua). SpecViz is built on top of the Specutils (ascl:1902.012) Astropy-affiliated python library, providing a visual, interactive interface to the analysis capabilities in that library.

[ascl:1210.016]
Specview: 1-D spectral visualization and analysis of astronomical spectrograms

Specview is a tool for 1-D spectral visualization and analysis of astronomical spectrograms. Written in Java, it is capable of reading all the Hubble Space Telescope spectral data formats as well as data from several other instruments (such as IUE, FUSE, ISO, FORS and SDSS), preview spectra from MAST, and data from generic FITS and ASCII tables. It can read data from Virtual Observatory servers, and read and write spectrogram data in Virtual Observatory SED format. It can also read files in the SPC Galactic format used in the chemistry field. Once ingested, data can be plotted and examined with a large selection of custom settings. Specview supports instrument-specific data quality handling, flexible spectral units conversions, custom plotting attributes, plot annotations, tiled plots, hardcopy to JPEG files and PostScript file or printer, etc. Specview can be used to build wide-band SEDs, overplotting or combining data from the same astronomical source taken with different instruments and/or spectral bands. Data can be further processed with averaging, splicing, detrending, and Fourier filtering tools. Specview has a spectral model fitting capability that enables the user to work with multi-component models (including user-defined models) and fit models to data.

[ascl:1902.012]
Specutils: Spectroscopic analysis and reduction

Specutils provides a basic interface for the loading, manipulation, and common forms of analysis of spectroscopic data. Its generic data containers and accompanying modules can be used to build a particular scientific workflow or higher-level analysis tool. It is an AstroPy (ascl:1304.002) affiliated package, and SpecViz (ascl:1902.011), which is built on top of Specutils, provides a visual, interactive interface to its analysis capabilities.

[ascl:9910.002]
SPECTRUM: A stellar spectral synthesis program

SPECTRUM ((C) Richard O. Gray, 1992-2008) is a stellar spectral synthesis program which runs on a number of platforms, including most flavors of UNIX and LINUX. It will also run under Windwos 9x/ME/NT/2000/XP using the Cygwin tools or the distributed Windows binaries. The code for SPECTRUM has been written in the "C" language. SPECTRUM computes the LTE synthetic spectrum given a stellar atmosphere model. SPECTRUM can use as input the fully blanketed stellar atmosphere models of Robert Kurucz including the new models of Castelli and Kurucz, but any other stellar atmosphere model which can be cast into the format of Kurucz's models can be used as well. SPECTRUM can be programmed with "command-line switches" to give a number of different outputs. In the default mode, SPECTRUM computes the stellar-disk-integrated normalized-intensity spectrum, but in addition, SPECTRUM will compute the absolute monochromatic flux from the stellar atmosphere or the specific intensity from any point on the stellar surface.

[ascl:1202.010]
SPECTRE: Manipulation of single-order spectra

SPECTRE's chief purpose is the manipulation of single-order spectra, and it performs many of the tasks contained in such IRAF routines as "splot" and "rv". It is not meant to replace the much more general capabilities of IRAF, but does some functions in a manner that some might find useful. A brief list of SPECTRE tasks are: spectrum smoothing; equivalent width calculation; continuum rectification; noise spike excision; and spectrum comparison. SPECTRE was written to manipulate coude spectra, and thus is probably most useful for working on high dispersion spectra. Echelle spectra can be gathered from various observatories, reduced to singly-dimensioned spectra using IRAF, then written out as FITS files, thus becoming accessible to SPECTRE. Three different spectra may be manipulated and displayed simultaneously. SPECTRE, written in standard FORTRAN77, can be used only with the SM graphics package.

[ascl:1609.017]
spectral-cube: Read and analyze astrophysical spectral data cubes

Spectral-cube provides an easy way to read, manipulate, analyze, and write data cubes with two positional dimensions and one spectral dimension, optionally with Stokes parameters. It is a versatile data container for building custom analysis routines. It provides a uniform interface to spectral cubes, robust to the wide range of conventions of axis order, spatial projections, and spectral units that exist in the wild, and allows easy extraction of cube sub-regions using physical coordinates. It has the ability to create, combine, and apply masks to datasets and is designed to work with datasets too large to load into memory, and provide basic summary statistic methods like moments and array aggregates.

[ascl:1701.003]
Spectra: Time series power spectrum calculator

Spectra calculates the power spectrum of a time series equally spaced or not based on the Spectral Correlation Coefficient (Ferraz-Mello 1981, Astron. Journal 86 (4), 619). It is very efficient for detection of low frequencies.

[ascl:1111.005]
SPECTCOL: Spectroscopic and Collisional Data Retrieval

Studies of astrophysical non-LTE media require the combination of atomic and molecular spectroscopic and collisional data often described differently in various databases. SPECTCOL is a tool that implements VAMDC standards, retrieve relevant information from different databases such as CDMS, HITRAN, BASECOL, and can upload local files. All transfer of data between the client and the databases use the VAMDC-XSAMS schema. The spectroscopic and collisional information is combined and useful outputs (ascii or xsams) are provided for the study of the interstellar medium.

[ascl:1904.018]
Specstack: A simple spectral stacking tool

Specstack creates stacked spectra using a simple algorithm with sigma-clipping to combine the spectra of galaxies in the rest-frame into a single averaged spectrum. Though written originally for galaxy spectra, it also works for other types of objects. It is written in Python and is started from the command-line.

[ascl:1404.014]
SpecPro: Astronomical spectra viewer and analyzer

SpecPro is an interactive program for viewing and analyzing spectra, particularly in the context of modern imaging surveys. In addition to displaying the 1D and 2D spectrum, SpecPro can simultaneously display available stamp images as well as the spectral energy distribution of a source. This extra information can help significantly in assessing a spectrum.

[ascl:1407.003]
SPECDRE: Spectroscopy Data Reduction

Specdre performs spectroscopy data reduction and analysis. General features of the package include data cube manipulation, arc line calibration, resampling and spectral fitting. Particular care is taken with error propagation, including tracking covariance. SPECDRE is distributed as part of the Starlink software collection (ascl:1110.012).

[ascl:1203.003]
spec2d: DEEP2 DEIMOS Spectral Pipeline

The DEEP2 DEIMOS Data Reduction Pipeline ("spec2d") is an IDL-based, automated software package designed to reduce Keck/DEIMOS multi-slit spectroscopic observations, collected as part of the DEEP2 Galaxy Redshift Survey. The pipeline is best suited for handling data taken with the 1200 line/mm grating tilted towards the red (lambda_c ~ 7800Å). The spec2d reduction package takes the raw DEIMOS data as its input and produces a variety of outputs including 2-d slit spectra and 1-d object spectra.

[ascl:1010.016]
SpDust/SpDust.2: Code to Calculate Spinning Dust Spectra

SpDust is an IDL program that evaluates the spinning dust emissivity for user-provided environmental conditions. A new version of the code became available in March, 2010.

[ascl:1711.001]
SpcAudace: Spectroscopic processing and analysis package of Audela software

SpcAudace processes long slit spectra with automated pipelines and performs astrophysical analysis of the latter data. These powerful pipelines do all the required steps in one pass: standard preprocessing, masking of bad pixels, geometric corrections, registration, optimized spectrum extraction, wavelength calibration and instrumental response computation and correction. Both high and low resolution long slit spectra are managed for stellar and non-stellar targets. Many types of publication-quality figures can be easily produced: pdf and png plots or annotated time series plots. Astrophysical quantities can be derived from individual or large amount of spectra with advanced functions: from line profile characteristics to equivalent width and periodogram. More than 300 documented functions are available and can be used into TCL scripts for automation. SpcAudace is based on Audela open source software.

[ascl:1511.011]
SparsePZ: Sparse Representation of Photometric Redshift PDFs

SparsePZ uses sparse basis representation to fully represent individual photometric redshift probability density functions (PDFs). This approach requires approximately half the parameters for the same multi-Gaussian fitting accuracy, and has the additional advantage that an entire PDF can be stored by using a 4-byte integer per basis function. Only 10-20 points per galaxy are needed to reconstruct both the individual PDFs and the ensemble redshift distribution, N(z), to an accuracy of 99.9 per cent when compared to the one built using the original PDFs computed with a resolution of δz = 0.01, reducing the required storage of 200 original values by a factor of 10-20. This basis representation can be directly extended to a cosmological analysis, thereby increasing computational performance without losing resolution or accuracy.

[ascl:1905.013]
SPARK: K-band Multi Object Spectrograph data reduction

SPARK (Software Package for Astronomical Reduction with KMOS) reduces data from the K-band Multi Object Spectrograph (KMOS) for the VLT. In many cases, science data can be processed using a single recipe; alternately, all functions this recipe provides can be performed using other recipes provided as tools. Among the functions the recipes provide are sky subtraction, cube reconstruction with the application of flexure corrections, dividing out the telluric spectrum, applying an illumination correction, aligning the cubes, and then combinging them. The result is a set of files which contain the combined datacube and associated noise cube for each of the 24 integral field unit (IFUs). The pipeline includes simple error propagation.

[ascl:1105.006]
SPARC: Seismic Propagation through Active Regions and Convection

The Seismic Propagation through Active Regions and Convection (SPARC) code was developed by S. Hanasoge. The acoustic wavefield in SPARC is simulated by numerically solving the linearised 3-D Euler equations in Cartesian geometry (e.g., see Hanasoge, Duvall and Couvidat (2007)). Spatial derivatives are calculated using sixth-order compact finite differences (Lele,1992) and time evolution is achieved through the repeated application of an optimized second-order five-stage Runge-Kutta scheme (Hu, 1996). Periodic horizontal boundaries are used.

[ascl:1812.005]
SPAMCART: Smoothed PArticle Monte CArlo Radiative Transfer

SPAMCART generates synthetic spectral energy distributions and intensity maps from smoothed particle hydrodynamics simulation snapshots. It follows discrete luminosity packets as they propagate through a density field, and computes the radiative equilibrium temperature of the ambient dust from their trajectories. The sources can be extended and/or embedded, and discrete and/or diffuse. The density is not mapped on to a grid, and therefore the calculation is performed at exactly the same resolution as the hydrodynamics. The code strictly adheres to Kirchhoff's law of radiation. The algorithm is based on the Lucy Monte Carlo radiative transfer method and is fairly simple to implement, as it uses data structures that are already constructed for other purposes in modern particle codes

[ascl:1408.006]
SPAM: Source Peeling and Atmospheric Modeling

SPAM is a extension to AIPS for reducing high-resolution, low-frequency radio interferometric observations. Direction-dependent ionospheric calibration and image-plane ripple suppression are among the features that help to make high-quality sub-GHz images. Data reductions are captured in well-tested Python scripts that execute AIPS tasks directly (mostly during initial data reduction steps), call high-level functions that make multiple AIPS or ParselTongue calls, and require few manual operations.

[ascl:1907.007]
SPAM: Hu-Sawicki f(R) gravity imprints search

SPAM searches for imprints of Hu-Sawicki f(R) gravity on the rotation curves of the SPARC (Spitzer Photometry and Accurate Rotation Curves) sample using the MCMC sampler emcee (ascl:1303.002). The code provides attributes for inspecting the MCMC chains and translating names of parameters to indices. The SPAM package also contains plotting scripts.

[ascl:1806.010]
SpaghettiLens: Web-based gravitational lens modeling tool

SpaghettiLens allows citizen scientists to model gravitational lenses collaboratively; the software should also be easily adaptable to any other, reasonably similar problem. It lets volunteers execute a computer intensive task that cannot be easily executed client side and relies on citizen scientists collaborating. SpaghettiLens makes survey data available to citizen scientists, manages the model configurations generated by the volunteers, stores the resulting model configuration, and delivers the actual model. A model can be shared and discussed with other volunteers and revised, and new child models can be created, resulting in a branching version tree of models that explore different possibilities. Scientists can choose a collection of models; discussion among volunteers and scientists prune the tree to determine which models will receive further analysis.

[ascl:1401.002]
SpacePy: Python-Based Tools for the Space Science Community

SpacePy provides data analysis and visualization tools for the space science community. Written in Python, it builds on the capabilities of the NumPy and MatPlotLib packages to make basic data analysis, modeling and visualization easier. It contains modules for handling many complex time formats, obtaining data from the OMNI database, and accessing the powerful Onera library. It contains a library of commonly used empirical relationships, performs association analysis, coordinate transformations, radiation belt modeling, and CDF reading, and creates publication quality plots.

[ascl:1504.002]
SPA: Solar Position Algorithm

The Solar Position Algorithm (SPA) calculates the solar zenith and azimuth angles in the period from the year -2000 to 6000, with uncertainties of +/- 0.0003 degrees based on the date, time, and location on Earth. SPA is implemented in C; in addition to being available for download, an online calculator using this code is available at http://www.nrel.gov/midc/solpos/spa.html.

[ascl:1805.028]
SP_Ace: Stellar Parameters And Chemical abundances Estimator

SP_Ace (Stellar Parameters And Chemical abundances Estimator) estimates the stellar parameters Teff, log g, [M/H], and elemental abundances. It employs 1D stellar atmosphere models in Local Thermodynamic Equilibrium (LTE). The code is highly automated and suitable for analyzing the spectra of large spectroscopic surveys with low or medium spectral resolution (R = 2000-20 000). A web service for calculating these values with the software is also available.

[ascl:1307.020]
SOPT: Sparse OPTimisation

SOPT (Sparse OPTimisation) is a C implementation of the Sparsity Averaging Reweighted Analysis (SARA) algorithm. The approach relies on the observation that natural images exhibit strong average sparsity; average sparsity outperforms state-of-the-art priors that promote sparsity in a single orthonormal basis or redundant frame, or that promote gradient sparsity.

[ascl:1607.014]
SOPIE: Sequential Off-Pulse Interval Estimation

SOPIE (Sequential Off-Pulse Interval Estimation) provides functions to non-parametrically estimate the off-pulse interval of a source function originating from a pulsar. The technique is based on a sequential application of P-values obtained from goodness-of-fit tests for the uniform distribution, such as the Kolmogorov-Smirnov, Cramér-von Mises, Anderson-Darling and Rayleigh goodness-of-fit tests.

[ascl:1810.017]
SOPHISM: Software Instrument Simulator

Blanco Rodríguez, J.; del Toro Iniesta, J. C.; Orozco Suárez, D.; Martínez Pillet, V.; Bonet, J. A.; Feller, A.; Hirzberger, J.; Lagg, A.; Piqueras, J.; Gasent Blesa, J. L.

SOPHISM models astronomical instrumentation from the entrance of the telescope to data acquisition at the detector, along with software blocks dealing with, for example, demodulation, inversion, and compression. The code performs most analyses done with light in astronomy, such as differential photometry, spectroscopy, and polarimetry. The simulator offers flexibility and implementation of new effects and subsystems, making it user-adaptable for a wide variety of instruments. SOPHISM can be used for all stages of instrument definition, design, operation, and lifetime tracking evaluation.

[ascl:1412.014]
SOPHIA: Simulations Of Photo Hadronic Interactions in Astrophysics

SOPHIA (Simulations Of Photo Hadronic Interactions in Astrophysics) solves problems connected to photohadronic processes in astrophysical environments and can also be used for radiation and background studies at high energy colliders such as LEP2 and HERA, as well as for simulations of photon induced air showers. SOPHIA implements well established phenomenological models, symmetries of hadronic interactions in a way that describes correctly the available exclusive and inclusive photohadronic cross section data obtained at fixed target and collider experiments.

[ascl:1701.012]
SONG: Second Order Non-Gaussianity

SONG computes the non-linear evolution of the Universe in order to predict cosmological observables such as the bispectrum of the Cosmic Microwave Background (CMB). More precisely, it is a second-order Boltzmann code, as it solves the Einstein and Boltzmann equations up to second order in the cosmological perturbations.

[ascl:1208.013]
SolarSoft: Programming and data analysis environment for solar physics

SolarSoft is a set of integrated software libraries, data bases, and system utilities which provide a common programming and data analysis environment for Solar Physics. The SolarSoftWare (SSW) system is built from Yohkoh, SOHO, SDAC and Astronomy libraries and draws upon contributions from many members of those projects. It is primarily an IDL based system, although some instrument teams integrate executables written in other languages. The SSW environment provides a consistent look and feel at widely distributed co-investigator institutions to facilitate data exchange and to stimulate coordinated analysis. Commonalities and overlap in solar data and analysis goals are exploited to permit application of fundamental utilities to the data from many different solar instruments. The use of common libraries, utilities, techniques and interfaces minimizes the learning curve for investigators who are analyzing new solar data sets, correlating results from multiple experiments or performing research away from their home institution.

[ascl:1412.001]
SoFiA: Source Finding Application

Serra, Paolo; Westmeier, Tobias; Giese, Nadine; Jurek, Russell; Flöer, Lars; Popping, Attila; Winkel, Benjamin; van der Hulst, Thijs; Meyer, Martin; Koribalski, Bärbel; Staveley-Smith, Lister; Courtois, Hélène

SoFiA is a flexible source finding pipeline designed to detect and parameterise sources in 3D spectral-line data cubes. SoFiA combines several powerful source finding and parameterisation algorithms, including wavelet denoising, spatial and spectral smoothing, source mask optimisation, spectral profile fitting, and calculation of the reliability of detections. In addition to source catalogues in different formats, SoFiA can also generate a range of output data cubes and images, including source masks, moment maps, sub-cubes, position-velocity diagrams, and integrated spectra. The pipeline is controlled by simple parameter files and can either be invoked on the command line or interactively through a modern graphical user interface.

[ascl:1403.026]
SOFA: Standards of Fundamental Astronomy

SOFA (Standards Of Fundamental Astronomy) is a collection of subprograms, in source-code form, that implement official IAU algorithms for fundamental astronomy computations. SOFA offers more than 160 routines for fundamental astronomy, including time scales (including dealing with leap seconds), Earth rotation, sidereal time, precession, nutation, polar motion, astrometry and transforms between various reference systems (e.g. BCRS, ICRS, GCRS, CIRS, TIRS, ITRS). The subprograms are supported by 55 vector/matrix routines, and are available in both Fortran77 and C implementations.

[ascl:1504.021]
SOAP 2.0: Spot Oscillation And Planet 2.0

SOAP (Spot Oscillation And Planet) 2.0 simulates the effects of dark spots and bright plages on the surface of a rotating star, computing their expected radial velocity and photometric signatures. It includes the convective blueshift and its inhibition in active regions.

[ascl:1902.001]
SNTD: Supernova Time Delays

Supernova Time Delays (SNTD) simulates and measures time delay of multiply-imaged supernovae, and offers an improved characterization of the uncertainty caused by microlensing. Lensing time delays can be determined by fitting the multiple light curves of these objects; measuring these delays provide precise tests of lens models or constraints on the Hubble constant and other cosmological parameters that are independent of the local distance ladder. Fitting the effects of microlensing without an accurate prior often leads to biases in the time delay measurement and over-fitting to the data; this can be mitigated by using a Gaussian Process Regression (GPR) technique to determine the uncertainty due to microlensing. SNTD can produce accurate simulations for wide-field time domain surveys such as LSST and WFIRST.

[ascl:1805.017]
SNSEDextend: SuperNova Spectral Energy Distributions extrapolation toolkit

Pierel, Justin D. R.; Rodney, Steven A.; Avelino, Arturo; Bianco, Federica; Foley, Ryan J.; Friedman, Andrew; Hicken, Malcolm; Hounsell, Rebekah; Jha, Saurabh W.; Kessler, Richard; Kirshner, Robert; Mandel, Kaisey; Narayan, Gautham; Filippenko, Alexei V.; Scolnic, Daniel; Strolger, Louis-Gregory

SNSEDextend extrapolates core-collapse and Type Ia Spectral Energy Distributions (SEDs) into the UV and IR for use in simulations and photometric classifications. The user provides a library of existing SED templates (such as those in the authors' SN SED Repository) along with new photometric constraints in the UV and/or NIR wavelength ranges. The software then extends the existing template SEDs so their colors match the input data at all phases. SNSEDextend can also extend the SALT2 spectral time-series model for Type Ia SN for a "first-order" extrapolation of the SALT2 model components, suitable for use in survey simulations and photometric classification tools; as the code does not do a rigorous re-training of the SALT2 model, the results should not be relied on for precision applications such as light curve fitting for cosmology.

[ascl:1703.006]
SNRPy: Supernova remnant evolution modeling

SNRPy (Super Nova Remnant Python) models supernova remnant (SNR) evolution and is useful for understanding SNR evolution and to model observations of SNR for obtaining good estimates of SNR properties. It includes all phases for the standard path of evolution for spherically symmetric SNRs and includes alternate evolutionary models, including evolution in a cloudy ISM, the fractional energy loss model, and evolution in a hot low-density ISM. The graphical interface takes in various parameters and produces outputs such as shock radius and velocity vs. time, SNR surface brightness profile and spectrum.

[ascl:1505.023]
SNooPy: TypeIa supernovae analysis tools

Burns, Christopher R.; Stritzinger, Maximilian; Phillips, M. M.; Kattner, ShiAnne; Persson, S. E.; Madore, Barry F.; Freedman, Wendy L.; Boldt, Luis; Campillay, Abdo; Contreras, Carlos; Folatelli, Gaston; Gonzalez, Sergio; Krzeminski, Wojtek; Morrell, Nidia; Salgado, Francisco; Suntzeff, Nicholas B.

The SNooPy package (also known as SNpy), written in Python, contains tools for the analysis of TypeIa supernovae. It offers interactive plotting of light-curve data and models (and spectra), computation of reddening laws and K-corrections, LM non-linear least-squares fitting of light-curve data, and various types of spline fitting, including Diercx and tension. The package also includes a SNIa lightcurve template generator in the CSP passbands, estimates of Milky-Way Extinction, and a module for dealing with filters and spectra.

[ascl:1505.022]
Snoopy: General purpose spectral solver

Snoopy is a spectral 3D code that solves the MHD and Boussinesq equations, such as compressibility, particles, and Braginskii viscosity, and several other physical effects. It's useful for turbulence study involving shear and rotation. Snoopy requires the FFTW library (ascl:1201.015), and can run on parallel machine using MPI OpenMP or both at the same time.

[ascl:1107.001]
SNID: Supernova Identification

We present an algorithm to identify the type of an SN spectrum and to determine its redshift and age. This algorithm, based on the correlation techniques of Tonry & Davis, is implemented in the Supernova Identification (SNID) code. It is used by members of ongoing high-redshift SN searches to distinguish between type Ia and type Ib/c SNe, and to identify "peculiar" SNe Ia. We develop a diagnostic to quantify the quality of a correlation between the input and template spectra, which enables a formal evaluation of the associated redshift error. Furthermore, by comparing the correlation redshifts obtained using SNID with those determined from narrow lines in the SN host galaxy spectrum, we show that accurate redshifts (with a typical error less than 0.01) can be determined for SNe Ia without a spectrum of the host galaxy. Last, the age of an input spectrum is determined with a typical 3-day accuracy, shown here by using high-redshift SNe Ia with well-sampled light curves. The success of the correlation technique confirms the similarity of some SNe Ia at low and high redshifts. The SNID code, which is available to the community, can also be used for comparative studies of SN spectra, as well as comparisons between data and models.

[ascl:1505.033]
SNEC: SuperNova Explosion Code

SNEC (SuperNova Explosion Code) is a spherically-symmetric Lagrangian radiation-hydrodynamics code that follows supernova explosions through the envelope of their progenitor star, produces bolometric (and approximate multi-color) light curve predictions, and provides input to spectral synthesis codes for spectral modeling. SNEC's features include 1D (spherical) Lagrangian Newtonian hydrodynamics with artificial viscosity, stellar equation of state with a Saha solver ionization/recombination, equilibrium flux-limited photon diffusion with OPAL opacities and low-temperature opacities, and prediction of bolometric light curves and multi-color lightcurves (in the blackbody approximation).

[ascl:1611.017]
SNCosmo: Python library for supernova cosmology

Barbary, Kyle; Barclay, Tom; Biswas, Rahul; Craig, Matt; Feindt, Ulrich; Friesen, Brian; Goldstein, Danny; Jha, Saurabh; Rodney, Steve; Sofiatti, Caroline; Thomas, Rollin C.; Wood-Vasey, Michael

SNCosmo synthesizes supernova spectra and photometry from SN models, and has functions for fitting and sampling SN model parameters given photometric light curve data. It offers fast implementations of several commonly used extinction laws and can be used to construct SN models that include dust. The SNCosmo library includes supernova models such as SALT2, MLCS2k2, Hsiao, Nugent, PSNID, SNANA and Whalen models, as well as a variety of built-in bandpasses and magnitude systems, and provides convenience functions for reading and writing peculiar data formats used in other packages. The library is extensible, allowing new models, bandpasses, and magnitude systems to be defined using an object-oriented interface.

[ascl:1010.027]
SNANA: A Public Software Package for Supernova Analysis

Kessler, Richard; Bernstein, Joseph P.; Cinabro, David; Dilday, Benjamin; Frieman, Joshua A.; Jha, Saurabh; Kuhlmann, Stephen; Miknaitis, Gajus; Sako, Masao; Taylor, Matt; VanderPlas, Jake

SNANA is a general analysis package for supernova (SN) light curves that contains a simulation, light curve fitter, and cosmology fitter. The software is designed with the primary goal of using SNe Ia as distance indicators for the determination of cosmological parameters, but it can also be used to study efficiencies for analyses of SN rates, estimate contamination from non-Ia SNe, and optimize future surveys. Several SN models are available within the same software architecture, allowing technical features such as K-corrections to be consistently used among multiple models, and thus making it easier to make detailed comparisons between models. New and improved light-curve models can be easily added. The software works with arbitrary surveys and telescopes and has already been used by several collaborations, leading to more robust and easy-to-use code. This software is not intended as a final product release, but rather it is designed to undergo continual improvements from the community as more is learned about SNe.

[ascl:1310.007]
SMURF: SubMillimeter User Reduction Facility

Jenness, Tim; Chapin, Edward L.; Berry, David S.; Gibb, Andy G.; Tilanus, Remo P. J.; Balfour, Jennifer; Tilanus, Vincent; Currie, Malcolm J.

SMURF reduces submillimeter single-dish continuum and heterodyne data. It is mainly targeted at data produced by the James Clerk Maxwell Telescope but data from other telescopes have been reduced using the package. SMURF is released as part of the bundle that comprises Starlink (ascl:1110.012) and most of the packages that use it. The two key commands are MAKEMAP for the creation of maps from sub millimeter continuum data and MAKECUBE for the creation of data cubes from heterodyne array instruments. The software can also convert data from legacy JCMT file formats to the modern form to allow it to be processed by MAKECUBE. SMURF is a core component of the ORAC-DR (ascl:1310.001) data reduction pipeline for JCMT.

[ascl:1303.005]
SMMOL: Spherical Multi-level MOLecular line radiative transfer

SMMOL (Spherical Multi-level MOLecular line radiative transfer) is a molecular line radiative transfer code that uses Accelerated Lambda Iteration to solve the coupled level population and line transfer problem in spherical geometry. The code uses a discretized grid and a ray tracing methodology. SMMOL is designed for high optical depth regimes and can cope with maser emission as long as the spatial-velocity sampling is fine enough.

[ascl:1904.005]
SMILI: Sparse Modeling Imaging Library for Interferometry

Akiyama, Kazunori; Tazaki, Fumie; Moriyama, Kotaro; Cho, Ilje; Ikeda, Shiro; Sasada, Mahito; Okino, Hiroki; Honma, Mareki

SMILI uses sparse sampling techniques and other regularization methods for interferometric imaging. The python-interfaced library is mainly designed for very long baseline interferometry, and has been under the active development primarily for the Event Horizon Telescope (EHT).

[ascl:1308.001]
SMILE: Orbital analysis and Schwarzschild modeling of triaxial stellar systems

SMILE is interactive software for studying a variety of 2D and 3D models, including arbitrary potentials represented by a basis-set expansion, a spherical-harmonic expansion with coefficients being smooth functions of radius (splines), or a set of fixed point masses. Its main features include:

- orbit integration in various 2d and 3d potentials (including N-body and basis-set representations of an arbitrary potential);
- methods for analysis of orbital class, fundamental frequencies, regular or chaotic nature of an orbit, computation of Lyapunov exponents;
- Poincaré sections (in 2d) and frequency maps (in 3d) for analyzing orbital structure of potential;
- construction of self-consistent Schwarzschild models; and
- convenient visualization and integrated GUI environment, and a console scriptable version.

[ascl:1804.010]
SMERFS: Stochastic Markov Evaluation of Random Fields on the Sphere

SMERFS (Stochastic Markov Evaluation of Random Fields on the Sphere) creates large realizations of random fields on the sphere. It uses a fast algorithm based on Markov properties and fast Fourier Transforms in 1d that generates samples on an n *X* n grid in O(*n*^{2} log *n*) and efficiently derives the necessary conditional covariance matrices.

[ascl:1202.013]
SME: Spectroscopy Made Easy

Spectroscopy Made Easy (SME) is IDL software and a compiled external library that fits an observed high-resolution stellar spectrum with a synthetic spectrum to determine stellar parameters. The SME external library is available for Mac, Linux, and Windows systems. Atomic and molecular line data formatted for SME may be obtained from VALD. SME can solve for empirical log(gf) and damping parameters, using an observed spectrum of a star (usually the Sun) as a constraint.

[ascl:1603.007]
SMARTIES: Spheroids Modelled Accurately with a Robust T-matrix Implementation for Electromagnetic Scattering

SMARTIES calculates the optical properties of oblate and prolate spheroidal particles, with comparable capabilities and ease-of-use as Mie theory for spheres. This suite of MATLAB codes provides a fully documented implementation of an improved T-matrix algorithm for the theoretical modelling of electromagnetic scattering by particles of spheroidal shape. Included are scripts that cover a range of scattering problems relevant to nanophotonics and plasmonics, including calculation of far-field scattering and absorption cross-sections for fixed incidence orientation, orientation-averaged cross-sections and scattering matrix, surface-field calculations as well as near-fields, wavelength-dependent near-field and far-field properties, and access to lower-level functions implementing the T-matrix calculations, including the T-matrix elements which may be calculated more accurately than with competing codes.

[ascl:1210.021]
SMART: Spectroscopic Modeling Analysis and Reduction Tool

SMART is an IDL-based software tool, developed by the IRS Instrument Team at Cornell University, that allows users to reduce and analyze Spitzer data from all four modules of the Infrared Spectrograph, including the peak-up arrays. The software is designed to make full use of the ancillary files generated in the Spitzer Science Center pipeline so that it can either remove or flag artifacts and corrupted data and maximize the signal-to-noise ratio in the extraction routines. It can be run in both interactive and batch modes. SMART includes visualization tools for assessing data quality, basic arithmetic operations for either two-dimensional images or one-dimensional spectra, extraction of both point and extended sources, and a suite of spectral analysis tools.

[ascl:1106.012]
SLUG: Stochastically Lighting Up Galaxies

The effects of stochasticity on the luminosities of stellar populations are an often neglected but crucial element for understanding populations in the low mass or low star formation rate regime. To address this issue, we present SLUG, a new code to "Stochastically Light Up Galaxies". SLUG synthesizes stellar populations using a Monte Carlo technique that treats stochastic sampling properly including the effects of clustering, the stellar initial mass function, star formation history, stellar evolution, and cluster disruption. This code produces many useful outputs, including i) catalogs of star clusters and their properties, such as their stellar initial mass distributions and their photometric properties in a variety of filters, ii) two dimensional histograms of color-magnitude diagrams of every star in the simulation, iii) and the photometric properties of field stars and the integrated photometry of the entire simulated galaxy. After presenting the SLUG algorithm in detail, we validate the code through comparisons with starburst99 in the well-sampled regime, and with observed photometry of Milky Way clusters. Finally, we demonstrate the SLUG's capabilities by presenting outputs in the stochastic regime.

[ascl:1010.035]
SLR: Stellar Locus Regression

Stellar Locus Regression (SLR) is a simple way to calibrate colors at the 1-2% level, and magnitudes at the sub-5% level as limited by 2MASS, without the traditional use of standard stars. With SLR, stars in any field are "standards." This is an entirely new way to calibrate photometry. SLR exploits the simple fact that most stars lie along a well defined line in color-color space called the stellar locus. Cross-match point-sources in flattened images taken through different passbands and plot up all color vs color combinations, and you will see the stellar locus with little effort. SLR calibrates colors by fitting these colors to a standard line. Cross-match with 2MASS on top of that, and SLR will deliver calibrated magnitudes as well.

[ascl:9906.001]
SLOPES: Least-squares linear regression lines for bivariate datasets

SLOPES computes six least-squares linear regression lines for bivariate datasets of the form (x_i,y_i) with unknown population distributions. Measurement errors, censoring (nondetections) or other complications are not treated. The lines are: the ordinary least-squares regression of y on x, OLS(Y|X); the inverse regression of x on y, OLS(X_Y); the angular bisector of the OLS lines; the orthogonal regression line; the reduced major axis, and the mean-OLS line. The latter four regressions treat the variables symmetrically, while the first two regressions are asymmetrical. Uncertainties for the regression coefficients of each method are estimated via asymptotic formulae, bootstrap resampling, and bivariate normal simulation. These methods, derivation of the regression coefficient uncertainties, and discussions of their use are provided in three papers listed below. The user is encouraged to read and reference these studies.

[ascl:1507.005]
slimplectic: Discrete non-conservative numerical integrator

slimplectic is a python implementation of a numerical integrator that uses a fixed time-step variational integrator formalism applied to the principle of stationary nonconservative action. It allows nonconservative effects to be included in the numerical evolution while preserving the major benefits of normally conservative symplectic integrators, particularly the accurate long-term evolution of momenta and energy. slimplectic is appropriate for exploring cosmological or celestial N-body dynamics problems where nonconservative interactions, e.g. dynamical friction or dissipative tides, can play an important role.

[ascl:1409.010]
Slim: Numerical data compression for scientific data sets

Slim performs lossless compression on binary data files. Written in C++, it operates very rapidly and achieves better compression on noisy physics data than general-purpose tools designed primarily for text.

[ascl:1105.004]
SLiM: A Code for the Simulation of Wave Propagation through an Inhomogeneous, Magnetised Solar Atmosphere

The semi-spectral linear MHD (SLiM) code follows the interaction of linear waves through an inhomogeneous three-dimensional solar atmosphere. The background model allows almost arbitrary perturbations of density, temperature, sound speed as well as magnetic and velocity fields. The code is useful in understanding the helioseismic signatures of various solar features, including sunspots.

[ascl:1611.021]
SlicerAstro: Astronomy (HI) extension for 3D Slicer

SlicerAstro extends 3D Slicer, a multi-platform package for visualization and medical image processing, to provide a 3-D interactive viewer with 3-D human-machine interaction features, based on traditional 2-D input/output hardware, and analysis capabilities.

[ascl:1403.025]
SLALIB: A Positional Astronomy Library

SLALIB is a library of routines that make accurate and reliable positional-astronomy applications easier to write. Most SLALIB routines are concerned with astronomical position and time, but a number have wider trigonometrical, numerical or general applications. A Fortran implementation of SLALIB under GPL licensing is available as part of Starlink (ascl:1110.012).

[ascl:1312.014]
SL1M: Synthesis through L1 Minimization

SL1M deconvolves radio synthesis images based on direct inversion of the measured visibilities that can deal with the non-coplanar base line effect and can be applied to telescopes with direction dependent gains. The code is more computationally demanding than some existing methods, but is highly parallelizable and scale well to clusters of CPUs and GPUs. The algorithm is also extremely flexible, allowing the solution of the deconvolution problem on arbitrarily placed pixels.

[ascl:1511.003]
SkyView Virtual Telescope

The SkyView Virtual telescope provides access to survey datasets ranging from radio through the gamma-ray regimes. Over 100 survey datasets are currently available. The SkyView library referenced here is used as the basis for the SkyView web site (at http://skvyiew.gsfc.nasa.gov) but is designed for individual use by researchers as well.

SkyView's approach to access surveys is distinct from most other toolkits. Rather than providing links to the original data, SkyView attempts to immediately re-render the source data in the user-requested reference frame, projection, scaling, orientation, etc. The library includes a set of geometry transformation and mosaicking tools that may be integrated into other applications independent of SkyView.

[ascl:1312.007]
SkyNet: Neural network training tool for machine learning in astronomy

SkyNet is an efficient and robust neural network training code for machine learning. It is able to train large and deep feed-forward neural networks, including autoencoders, for use in a wide range of supervised and unsupervised learning applications, such as regression, classification, density estimation, clustering and dimensionality reduction. SkyNet is implemented in C/C++ and fully parallelized using MPI.

[ascl:1710.005]
SkyNet: Modular nuclear reaction network library

The general-purpose nuclear reaction network SkyNet evolves the abundances of nuclear species under the influence of nuclear reactions. SkyNet can be used to compute the nucleosynthesis evolution in all astrophysical scenarios where nucleosynthesis occurs. Any list of isotopes can be evolved and SkyNet supports various different types of nuclear reactions. SkyNet is modular, permitting new or existing physics, such as nuclear reactions or equations of state, to be easily added or modified.

[ascl:1010.066]
SkyMaker: Astronomical Image Simulations Made Easy

SkyMaker is a program that simulates astronomical images. It accepts object lists in ASCII generated by the Stuff program to produce realistic astronomical fields. SkyMaker is part of the EFIGI development project.

[ascl:1408.007]
Skycorr: Sky emission subtraction for observations without plain sky information

Noll, S.; Kausch, W.; Kimeswenger, S.; Barden, M.; Jones, A. M.; Modigliani, A.; Szyszka, C.; Taylor, J.

Skycorr is an instrument-independent sky subtraction code that uses physically motivated line group scaling in the reference sky spectrum by a fitting approach for an improved sky line removal in the object spectrum. Possible wavelength shifts between both spectra are corrected by fitting Chebyshev polynomials and advanced rebinning without resolution decrease. For the correction, the optimized sky line spectrum and the automatically separated sky continuum (without scaling) is subtracted from the input object spectrum. Tests show that Skycorr performs well (per cent level residuals) for data in different wavelength regimes and of different resolution, even in the cases of relatively long time lags between the object and the reference sky spectrum. Lower quality results are mainly restricted to wavelengths not dominated by airglow lines or pseudo continua by unresolved strong emission bands.

[ascl:1109.019]
SkyCat: Visualization and Catalog and Data Access Tool

ESO's Data Management; Very Large Telescope (VLT) Project Divisions; Canadian Astronomical Data Center (CADC)

SkyCat is a tool that combines visualization of images and access to catalogs and archive data for astronomy. The tool, developed in Tcl/Tk, was originally conceived as a demo of the capabilities of the class library that was developed for the VLT. The Skycat sources currently consist of five packages:

- Tclutil - Generic Tcl and C++ utilities
- Astrotcl - Astronomical Tcl and C++ utilities
- RTD - Real-time Display classes and widgets
- Catlib - Catalog library and widgets
- Skycat - Skycat application and library package

[ascl:1609.014]
Sky3D: Time-dependent Hartree-Fock equation solver

Written in Fortran 90, Sky3D solves the static or dynamic equations on a three-dimensional Cartesian mesh with isolated or periodic boundary conditions and no further symmetry assumptions. Pairing can be included in the BCS approximation for the static case. The code can be easily modified to include additional physics or special analysis of the results and requires LAPACK and FFTW3.

[ascl:1109.003]
SKIRT: Stellar Kinematics Including Radiative Transfer

SKIRT is a radiative transfer code based on the Monte Carlo technique. The name SKIRT, acronym for Stellar Kinematics Including Radiative Transfer, reflects the original motivation for its creation: it has been developed to study the effects of dust absorption and scattering on the observed kinematics of dusty galaxies. In a second stage, the SKIRT code was extended with a module to self-consistently calculate the dust emission spectrum under the assumption of local thermal equilibrium. This LTE version of SKIRT has been used to model the dust extinction and emission of various types of galaxies, as well as circumstellar discs and clumpy tori around active galactic nuclei. A new, extended version of SKIRT code can perform efficient 3D radiative transfer calculations including a self-consistent calculation of the dust temperature distribution and the associated FIR/submm emission with a full incorporation of the emission of transiently heated grains and PAH molecules.

[ascl:1102.020]
SKID: Finding Gravitationally Bound Groups in N-body Simulations

SKID finds gravitationally bound groups in N-body simulations. The SKID program will group different types of particles depending on the type of input binary file. This could be either dark matter particles, gas particles, star particles or gas and star particles depending on what is in the input tipsy binary file. Once groups with at least a certain minimum number of members have been determined, SKID will remove particles which are not bound to the group. SKID must use the original positions of all the particles to determine whether or not particles are bound. This procedure which we call unbinding, is again dependent on the type of grouping we are dealing with. There are two cases, one for dark matter only or star particles only (case 1 unbinding), the other for inputs including gas (also stars in a dark matter environment this is case 2 unbinding).

Skid version 1.3 is a much improved version of the old denmax-1.1 version. The new name was given to avoid confusion with the DENMAX program of Gelb & Bertschinger, and although it is based on the same idea it represents a substantial evolution in the method.

[ascl:1903.002]
SIXTE: Simulation of X-ray Telescopes

SIXTE simulates X-Ray telescope observation; the software performs instrument performance analyses and produces simulated event files for mission and analysis studies. SIXTE strives to find a compromise between exactness of the simulation and speed. Using calibration files such as the PSF, RMF and ARF makes efficient simulations possible at comparably high speed, even though they include nonlinear effects such as pileup. Setups for some current and future missions, such as XMM-Newton and Athena, are included in the package; others can be added by the user with relatively little effort through specifying the main instrument characteristics in a flexible, human-readable XML-based format. Properties of X-ray sources to be simulated are described in a detector-independent format, i.e., the same input can be used for simulating observations with all available instruments, and the same input can also be used for simulations with the SIMX simulator. The input files are easily generated from standard data such as XSPEC (ascl:9910.005) spectral models or FITS images with tools provided with the SIXTE distribution. The input data scale well from single point sources up to very complicated setups.

[ascl:1111.008]
SITools2: A Framework for Archival Systems

SITools2 is a CNES generic tool performed by a joint effort between CNES and scientific laboratories. SITools provides a self-manageable data access layer deployed on already existing scientific laboratory databases. This new version of SITools is a JAVA-based framework, under open source license, that provides a portable archive system, highly configurable, easy to use by laboratories, with a plugin mechanism so developers can add their own applications.

[ascl:1212.008]
SIR: Stokes Inversion based on Response functions

SIR is a general-purpose code capable of dealing with gradients of the physical quantities with height. It admits one and two-component model atmospheres. It allows the recovery of the stratification of the temperature, the magnetic field vector, and the line of sight velocity through the atmosphere, and the micro- and macroturbulence velocities - which are assumed to be constant with depth. It is based on the response functions, which enter a Marquardt nonlinear least-squares algorithm in a natural way. Response functions are calculated at the same time as the full radiative transfer equation for polarized light is integrated, which determines values of many free parameters in a reasonable computation time. SIR demonstrates high stability, accuracy, and uniqueness of results, even when simulated observations present signal-to-noise ratios of the order of the lowest acceptable values in real observations.

[ascl:1609.018]
SIP: Systematics-Insensitive Periodograms

SIP (Systematics-Insensitive Periodograms) extends the generative model used to create traditional sine-fitting periodograms for finding the frequency of a sinusoid by including systematic trends based on a set of eigen light curves in the generative model in addition to using a sum of sine and cosine functions over a grid of frequencies, producing periodograms with vastly reduced systematic features. Acoustic oscillations in giant stars and measurement of stellar rotation periods can be recovered from the SIP periodograms without detrending. The code can also be applied to detection other periodic phenomena, including eclipsing binaries and short-period exoplanet candidates.

[ascl:1010.026]
SingLe: A F90-package devoted to Softened Gravity in gaseous discs

**S**often**ingLe**ngth: Because Newton's law of Gravitation diverges as the relative separations |r'-r| tends to zero, it is common to add a positive constant λ also known as the "softening length", i.e. :

|r'-r|² ← |r'-r|² + λ².

SingLe determines the appropriate value of this Softening Length λ for a given disc local structure (thickness 2h and vertical stratification ρ), in the axially symmetric, flat disc limit, preserving at best the Newtonian character of the gravitational potential and associated forces. Mass density ρ(z) is assumed to be locally expandable in the z-direction according to:

ρ(z)= ρ_{0}[1 + a_{1}(z/h)^{2}+...+a_{q} (z/h)^{2q}+...+a_{N} (z/h)^{2 N}].

[ascl:1708.019]
SINFONI Pipeline: Data reduction pipeline for the Very Large Telescope SINFONI spectrograph

The SINFONI pipeline reduces data from the Very Large Telescope's SINFONI (Spectrograph for INtegral Field Observations in the Near Infrared) instrument. It can evaluate the detector linearity and generate a corresponding non linear pixel map, create a master dark and a hot-pixel map, a master flat and a map of pixels which have intensities greater than a given threshold. It can also compute the optical distortions and slitlets distances, and perform wavelength calibration, PSF, telluric standard and other science data reduction, and can coadd bad pixel maps, collapse a cube to an image over a given wavelength range, perform cube arithmetics, among other useful tasks.

[ascl:1307.013]
SIMX: Event simulator

SIMX simulates a photon-counting detector's response to an input source, including a simplified model of any telescope. The code is not a full ray-trace, but a convolution tool that uses standard descriptions of telescope PSF (via either a simple Gaussian parameter, an energy-dependent encircled-energy function, or an image of the PSF) and the detector response (using the OGIP response function) to model how sources will appear. simx uses a predefined set of PSFs, vignetting information, and instrumental responses and outputs to make the simulation. It is designed to be a 'approximation' tool to estimate issues such as source confusion, background effects, pileup, and other similar issues.

[ascl:1904.016]
simuTrans: Gravity-darkened exoplanet transit simulator

simuTrans models transit light curves affected by gravity-darkened stars. The code defines a star on a grid by modeling the brightness of each point as blackbody emission, then sets a series of parameters and uses emcee (ascl:1303.002) to explore the posterior probability distribution for the remaining fitted parameters and determine their best-fit values.

[ascl:1903.006]
SimSpin: Kinematic analysis of galaxy simulations

The R-package SimSpin measures the kinematics of a galaxy simulation as if it had been observed using an IFU. The functions included in the package can produce a kinematic data cube and measure the "observables" from this data cube, specifically the observable spin parameter λr. This package, once installed, is fully documented and tested.

[ascl:1606.010]
SimpLens: Interactive gravitational lensing simulator

SimpLens illustrates some of the theoretical ideas important in gravitational lensing in an interactive way. After setting parameters for elliptical mass distribution and external mass, SimpLens displays the mass profile and source position, the lens potential and image locations, and indicate the image magnifications and contours of virtual light-travel time. A lens profile can be made shallower or steeper with little change in the image positions and with only total magnification affected.

[ascl:1110.022]
simple_cosfitter: Supernova-centric Cosmological Fitter

This is an implementation of a fairly simple-minded luminosity distance fitter, intended for use with supernova data. The calculational technique is based on evaluating the $chi^2$ of the model fit on a grid and marginalization over various nuisance parameters. Of course, the nature of these things is that this code has gotten steadily more complex, so perhaps the simple moniker is no longer justified.

[ascl:1010.025]
SimFast21: Simulation of the Cosmological 21cm Signal

SimFast 21 generates a simulation of the cosmological 21cm signal. While limited to low spatial resolution, the next generation low-frequency radio interferometers that target 21 cm observations during the era of reionization and prior will have instantaneous fields-of-view that are many tens of square degrees on the sky. Predictions related to various statistical measurements of the 21 cm brightness temperature must then be pursued with numerical simulations of reionization with correspondingly large volume box sizes, of order 1000 Mpc on one side. The authors pursued a semi-numerical scheme to simulate the 21 cm signal during and prior to Reionization by extending a hybrid approach where simulations are performed by first laying down the linear dark matter density field, accounting for the non-linear evolution of the density field based on second-order linear perturbation theory as specified by the Zel'dovich approximation, and then specifying the location and mass of collapsed dark matter halos using the excursion-set formalism. The location of ionizing sources and the time evolving distribution of ionization field is also specified using an excursion-set algorithm. They account for the brightness temperature evolution through the coupling between spin and gas temperature due to collisions, radiative coupling in the presence of Lyman-alpha photons and heating of the intergalactic medium, such as due to a background of X-ray photons. The method is capable of producing the required large volume simulations with adequate resolution in a reasonable time so a large number of realizations can be obtained with variations in assumptions related to astrophysics and background cosmology that govern the 21 cm signal.

[submitted]
SimCADO - An observations simulator for infrared telescopes and instruments

SimCADO is a python package which allows the user to simulate observations with any NIR/Vis imaging system. The package was originally designed to simulate images for the European extremely large telescope (ELT) and MICADO, however with the proper input it is capable of simulating observations from many different Telescope + Instrument configurations.

The documentation can be found here: https://simcado.readthedocs.io/en/latest/

[ascl:1811.011]
SIM5: Library for ray-tracing and radiation transport in general relativity

The SIM5 library contains routines for relativistic raytracing and radiation transfer in GR. Written C with a Python interface, it has a special focus on raytracing from accretion disks, tori, hot spots or any other 3D configuration of matter in Kerr geometry, but it can be used with any other metric as well. It handles both optically thick and thin sources as well as transport of polarization of the radiation and calculates the propagation of light rays from the source to an observer through a curved spacetime. It supports parallelization and runs on GPUs.

[ascl:1603.001]
SILSS: SPHERE/IRDIS Long-Slit Spectroscopy pipeline

The ESO's VLT/SPHERE instrument includes a unique long-slit spectroscopy (LSS) mode coupled with Lyot coronagraphy in its infrared dual-band imager and spectrograph (IRDIS) for spectral characterization of young, giant exoplanets detected by direct imaging. The SILSS pipeline is a combination of the official SPHERE pipeline and additional custom IDL routines developed within the SPHERE consortium for the speckle subtraction and spectral extraction of a companion's spectrum; it offers a complete end-to-end pipeline, from raw data (science+calibrations) to a final spectrum of the companion. SILSS works on both the low-resolution (LRS) and medium-resolution (MRS) data, and allows correction for some of the known biases of the instrument. Documentation is included in the header of the main routine of the pipeline.

[ascl:1107.016]
SIGPROC: Pulsar Signal Processing Programs

SIGPROC is a package designed to standardize the initial analysis of the many types of fast-sampled pulsar data. Currently recognized machines are the Wide Band Arecibo Pulsar Processor (WAPP), the Penn State Pulsar Machine (PSPM), the Arecibo Observatory Fourier Transform Machine (AOFTM), the Berkeley Pulsar Processors (BPP), the Parkes/Jodrell 1-bit filterbanks (SCAMP) and the filterbank at the Ooty radio telescope (OOTY). The SIGPROC tools should help users look at their data quickly, without the need to write (yet) another routine to read data or worry about big/little endian compatibility (byte swapping is handled automatically).

[ascl:1110.023]
SiFTO: An Empirical Method for Fitting SN Ia Light Curves

SiFTO is an empirical method for modeling Type Ia supernova (SN Ia) light curves by manipulating a spectral template. We make use of high-redshift SN data when training the model, allowing us to extend it bluer than rest-frame U. This increases the utility of our high-redshift SN observations by allowing us to use more of the available data. We find that when the shape of the light curve is described using a stretch prescription, applying the same stretch at all wavelengths is not an adequate description. SiFTO therefore uses a generalization of stretch which applies different stretch factors as a function of both the wavelength of the observed filter and the stretch in the rest-frame B band. SiFTO has been compared to other published light-curve models by applying them to the same set of SN photometry, and it's been demonstrated that SiFTO and SALT2 perform better than the alternatives when judged by the scatter around the best-fit luminosity distance relationship. When SiFTO and SALT2 are trained on the same data set the cosmological results agree.

[ascl:1703.007]
sidm-nbody: Monte Carlo N-body Simulation for Self-Interacting Dark Matter

Self-Interacting Dark Matter (SIDM) is a hypothetical model for cold dark matter in the Universe. A strong interaction between dark matter particles introduce a different physics inside dark-matter haloes, making the density profile cored, reduce the number of subhaloes, and trigger gravothermal collapse. sidm-nbody is an N-body simulation code with Direct Simulation Monte Carlo scattering for self interaction, and some codes to analyse gravothermal collapse of isolated haloes. The N-body simulation is based on GADGET 1.1.

[ascl:1905.024]
SICON: Stokes Inversion based on COnvolutional Neural networks

SICON (Stokes Inversion based on COnvolutional Neural networks) provides a three-dimensional cube of thermodynamical and magnetic properties from the interpretation of two-dimensional maps of Stokes profiles by use of a convolutional neural network. In addition to being much faster than parallelized inversion codes, SICON, when trained on synthetic Stokes profiles from two numerical simulations of different structures of the solar atmosphere, also provided a three-dimensional view of the physical properties of the region of interest in geometrical height, and pressure and Wilson depression properties that are decontaminated from the blurring effect of instrumental point spread functions.

[ascl:1706.009]
sick: Spectroscopic inference crank

sick infers astrophysical parameters from noisy observed spectra. Phenomena that can alter the data (e.g., redshift, continuum, instrumental broadening, outlier pixels) are modeled and simultaneously inferred with the astrophysical parameters of interest. This package relies on emcee (ascl:1303.002); it is best suited for situations where a grid of model spectra already exists, and one would like to infer model parameters given some data.

[ascl:1411.026]
sic: Sparse Inpainting Code

Feeney, Stephen M.; Marinucci, Domenico; McEwen, Jason D.; Peiris, Hiranya V.; Wandelt, Benjamin D.; Cammarota, Valentina

sic (Sparse Inpainting Code) generates Gaussian, isotropic CMB realizations, masks them, and recovers the large-scale masked data using sparse inpainting; it is written in Fortran90.

[ascl:1704.003]
Shwirl: Meaningful coloring of spectral cube data with volume rendering

Shwirl visualizes spectral data cubes with meaningful coloring methods. The program has been developed to investigate transfer functions, which combines volumetric elements (or voxels) to set the color, and graphics shaders, functions used to compute several properties of the final image such as color, depth, and/or transparency, as enablers for scientific visualization of astronomical data. The program uses Astropy (ascl:1304.002) to handle FITS files and World Coordinate System, Qt (and PyQt) for the user interface, and VisPy, an object-oriented Python visualization library binding onto OpenGL.

[ascl:1110.004]
SHTOOLS: Tools for Working with Spherical Harmonics

SHTOOLS is an archive of fortran 95 based software that can be used to perform (among others) spherical harmonic transforms and reconstructions, rotations of spherical harmonic coefficients, and multitaper spectral analyses on the sphere. The package accommodates any standard normalization of the spherical harmonic functions ("geodesy" 4π normalized, Schmidt semi-normalized, orthonormalized, and unnormalized), and either real or complex spherical harmonics can be employed. Spherical harmonic transforms are calculated by exact quadrature rules using either (1) the sampling theorem of Driscoll and Healy (1994) where data are equally sampled (or spaced) in latitude and longitude, or (2) Gauss-Legendre quadrature. A least squares inversion routine for irregularly sampled data is included as well. The Condon-Shortley phase factor of (-1)m can be used or excluded with the associated Legendre functions. The spherical harmonic transforms are accurate to approximately degree 2800, corresponding to a spatial resolution of better than 4 arc minutes. Routines are included for performing localized multitaper spectral analyses and standard gravity calculations, such as computation of the geoid, and the determination of the potential associated with finite-amplitude topography. The routines are fast. Spherical harmonic transforms and reconstructions take on the order of 1 second for bandwidths less than 600 and about 3 minutes for bandwidths close to 2800.

[ascl:1107.005]
Sherpa: CIAO Modeling and Fitting Package

Sherpa is the CIAO (ascl:1311.006) modeling and fitting application made available by the Chandra X-ray Center (CXC). It can be used for analysis of images, spectra and time series from many telescopes, including optical telescopes such as Hubble. Sherpa is flexible, modular and extensible. It has an IPython user interface and it is also an importable Python module. Sherpa models, optimization and statistic functions are available via both C++ and Python for software developers wishing to link such functions directly to their own compiled code.

The CIAO 4.3 Sherpa release supports fitting of 1-D X-ray spectra from Chandra and other X-ray missions, as well as 1-D non-X-ray data, including ASCII data arrays, radial profiles, and lightcurves. The options for grating data analysis include fitting the spectrum with multiple response files required for overlapping orders in LETG observations. Modeling of 2-D spatial data is fully supported, including the PSF and exposure maps. User specified models can be added to Sherpa with advanced "user model" functionality.

[ascl:1108.002]
SHERA: SHEar Reconvolution Analysis

Current and upcoming wide-field, ground-based, broad-band imaging surveys promise to address a wide range of outstanding problems in galaxy formation and cosmology. Several such uses of ground-based data, especially weak gravitational lensing, require highly precise measurements of galaxy image statistics with careful correction for the effects of the point-spread function (PSF). The SHERA (SHEar Reconvolution Analysis) software simulates ground-based imaging data with realistic galaxy morphologies and observing conditions, starting from space-based data (from COSMOS, the Cosmological Evolution Survey) and accounting for the effects of the space-based PSF. This code simulates ground-based data, optionally with a weak lensing shear applied, in a model-independent way using a general Fourier space formalism. The utility of this pipeline is that it allows for a precise, realistic assessment of systematic errors due to the method of data processing, for example in extracting weak lensing galaxy shape measurements or galaxy radial profiles, given user-supplied observational conditions and real galaxy morphologies. Moreover, the simulations allow for the empirical test of error estimates and determination of parameter degeneracies, via generation of many noise maps. The public release of this software, along with a large sample of cleaned COSMOS galaxy images (corrected for charge transfer inefficiency), should enable upcoming ground-based imaging surveys to achieve their potential in the areas of precision weak lensing analysis, galaxy profile measurement, and other applications involving detailed image analysis.

This code is no longer maintained and has been superseded by GalSim (ascl:1402.009).

[ascl:1108.017]
SHELLSPEC: Simple Radiative Transfer along Line of Sight in Moving Media

SHELLSPEC is designed to calculate lightcurves, spectra and images of interacting binaries and extrasolar planets immersed in a moving circumstellar environment which is optically thin. It solves simple radiative transfer along the line of sight in moving media. The assumptions include LTE and optional known state quantities and velocity fields in 3D. Optional (non)transparent objects such as a spot, disc, stream, jet, shell or stars as well as an empty space may be defined (embedded) in 3D and their composite synthetic spectrum calculated. Roche model can be used as a boundary condition for the radiative tranfer. The program does not solve the inverse problem of finding the stellar and orbital parameters.

[ascl:1508.010]
SHDOM: Spherical Harmonic Discrete Ordinate Method for atmospheric radiative transfer

The Spherical Harmonic Discrete Ordinate Method (SHDOM) radiative transfer model computes polarized monochromatic or spectral band radiative transfer in a one, two, or three-dimensional medium for either collimated solar and/or thermal emission sources of radiation. The model is written in a variant of Fortran 77 and in Fortran90 and requires a Fortran 90 compiler. Also included are programs for generating the optical property files input to SHDOM from physical properties of water cloud particles and aerosols.

[ascl:1811.005]
Shark: Flexible semi-analytic galaxy formation model

Lagos, Claudia del P.; Tobar, Rodrigo J.; Robotham, Aaron S. G.; Obreschkow, Danail; Mitchell, Peter D.; Power, Chris; Elahi, Pascal J.

Shark is a flexible semi-analytic galaxy formation model for easy exploration of different physical processes. Shark has been implemented with several models for gas cooling, active galactic nuclei, stellar and photo-ionization feedback, and star formation (SF). The software can determine the stellar mass function and stellar–halo mass relation at z=0–4; cosmic evolution of the star formation rate density, stellar mass, atomic and molecular hydrogen; local gas scaling relations; and structural galaxy properties. It performs particularly well for the mass–size relation for discs/bulges, the gas–stellar mass and stellar mass–metallicity relations. Shark is written in C++11 and has been parallelized with OpenMP.

[ascl:1307.014]
Shapelets: Image Modelling

Shapelets are a complete, orthonormal set of 2D basis functions constructed from Laguerre or Hermite polynomials weighted by a Gaussian. A linear combination of these functions can be used to model any image, in a similar way to Fourier or wavelet synthesis. The shapelet decomposition is particularly efficient for images localized in space, and provide a high level of compression for individual galaxies in astronomical data. The basis has many elegant mathematical properties that make it convenient for image analysis and processing.

[ascl:1204.010]
Shape: A 3D Modeling Tool for Astrophysics

Shape is a flexible interactive 3D morpho-kinematical modeling application for astrophysics. It reduces the restrictions on the physical assumptions, data type and amount required for a reconstruction of an object's morphology. It applies interactive graphics and allows astrophysicists to provide a-priori knowledge about the object by interactively defining 3D structural elements. By direct comparison of model prediction with observational data, model parameters can then be automatically optimized to fit the observation.

[ascl:1011.005]
Shape of Cosmic String Loops

Complicated cosmic string loops will fragment until they reach simple, non-intersecting ("stable") configurations. Through extensive numerical study we characterize these attractor loop shapes including their length, velocity, kink, and cusp distributions. We find that an initial loop containing $M$ harmonic modes will, on average, split into 3M stable loops. These stable loops are approximately described by the degenerate kinky loop, which is planar and rectangular, independently of the number of modes on the initial loop. This is confirmed by an analytic construction of a stable family of perturbed degenerate kinky loops. The average stable loop is also found to have a 40% chance of containing a cusp. We examine the properties of stable loops of different lengths and find only slight variation. Finally we develop a new analytic scheme to explicitly solve the string constraint equations.

[ascl:1605.003]
Shadowfax: Moving mesh hydrodynamical integration code

Shadowfax simulates galaxy evolution. Written in object-oriented modular C++, it evolves a mixture of gas, subject to the laws of hydrodynamics and gravity, and any collisionless fluid only subject to gravity, such as cold dark matter or stars. For the hydrodynamical integration, it makes use of a (co-) moving Lagrangian mesh. The code has a 2D and 3D version, contains utility programs to generate initial conditions and visualize simulation snapshots, and its input/output is compatible with a number of other simulation codes, e.g. Gadget2 (ascl:0003.001) and GIZMO (ascl:1410.003).

[ascl:1712.015]
SgrbWorldModel: Short-duration Gamma-Ray Burst World Model

SgrbWorldModel, written in Fortran 90, presents an attempt at modeling the population distribution of the Short-duration class of Gamma-Ray Bursts (SGRBs) as detected by the NASA's now-defunct Burst And Transient Source Experiment (BATSE) onboard the Compton Gamma Ray Observatory (CGRO). It is assumed that the population distribution of SGRBs is well fit by a multivariate log-normal distribution, whose differential cosmological rate of occurrence follows the Star-Formation-Rate (SFR) convolved with a log-normal binary-merger delay-time distribution. The best-fit parameters of the model are then found by maximizing the likelihood of the observed data by the BATSE detectors via a native built-in Adaptive Metropolis-Hastings Markov-Chain Monte Carlo (AMH-MCMC)Sampler that is part of the code. A model for the detection algorithm of the BATSE detectors is also provided.

[ascl:1210.005]
SGNAPS: Software for Graphical Navigation, Analysis and Plotting of Spectra

SGNAPS allows the user to plot a one-dimensional spectrum, together with the corresponding two-dimensional and a reference spectrum (for example the sky spectrum). This makes it possible to check on the reality of spectral features that are present in the one-dimensional spectrum, which could be due to bad sky subtraction or fringing residuals. It is also possible to zoom in and out all three spectra, edit the one-dimensional spectrum, smooth it with a simple square window function, measure the signal to noise over a selected wavelength interval, and fit the position of a selected spectral line. SGNAPS also allows the astronomer to obtain quick redshift estimates by providing a tool to fit or mark the position of a spectral line, and a function that will compute a list of possible redshifts based on a list of known lines in galaxy spectra. SGNAPS is derived from the plotting tools of VIPGI and contains almost all of their capabilities.

[ascl:1712.007]
SFoF: Friends-of-friends galaxy cluster detection algorithm

SFoF is a friends-of-friends galaxy cluster detection algorithm that operates in either spectroscopic or photometric redshift space. The linking parameters, both transverse and along the line-of-sight, change as a function of redshift to account for selection effects.

[ascl:1304.013]
SFH: Star Formation History

SFH is an efficient IDL tool that quickly computes accurate predictions for the baryon budget history in a galactic halo.

[ascl:1010.064]
SExtractor: Source Extractor

This new software optimally detects, de-blends, measures and classifies sources from astronomical images: SExtractor (Source Extractor). A very reliable star/galaxy separation can be achieved on most images using a neural network trained with simulated images. Salient features of SExtractor include its ability to work on very large images, with minimal human intervention, and to deal with a wide variety of object shapes and magnitudes. It is therefore particularly suited to the analysis of large extragalactic surveys.

[ascl:1508.006]
SExSeg: SExtractor segmentation

SExSeg forces SExtractor (ascl:1010.064) to run using a pre-defined segmentation map (the definition of objects and their borders). The defined segments double as isophotal apertures. SExSeg alters the detection image based on a pre-defined segmenation map while preparing your "analysis image" by subtracting the background in a separate SExtractor run (using parameters you specify). SExtractor is then run in "double-image" mode with the altered detection image and background-subtracted analysis image.

[ascl:1803.009]
SETI-EC: SETI Encryption Code

The SETI Encryption code, written in Python, creates a message for use in testing the decryptability of a simulated incoming interstellar message. The code uses images in a portable bit map (PBM) format, then writes the corresponding bits into the message, and finally returns both a PBM image and a text (TXT) file of the entire message. The natural constants (c, G, h) and the wavelength of the message are defined in the first few lines of the code, followed by the reading of the input files and their conversion into 757 strings of 359 bits to give one page. Each header of a page, i.e. the little-endian binary code translation of the tempo-spatial yardstick, is calculated and written on-the-fly for each page.

[ascl:1304.009]
Sérsic: Exact deprojection of Sérsic surface brightness profiles

Sérsic is an implementation of the exact deprojection of Sérsic surface brightness profiles described in Baes and Gentile (2011). This code depends on the mpmath python library for an implementation of the Meijer G function required by the Baes and Gentile (hereafter B+G) formulas for rational values of the Sérsic index. Sérsic requires rational Sérsic indices, but any irrational number can be approximated arbitrarily well by some rational number. The code also depends on scipy, but the dependence is mostly for testing. The implementation of the formulas and the formulas themselves have undergone comprehensive testing.

[ascl:1312.001]
SERPent: Scripted E-merlin Rfi-mitigation PipelinE for iNTerferometry

SERPent is an automated reduction and RFI-mitigation procedure that uses the SumThreshold methodology. It was originally developed for the LOFAR pipeline. SERPent is written in Parseltongue, enabling interaction with the Astronomical Image Processing Software (AIPS) program. Moreover, SERPent is a simple "out of the box" Python script, which is easy to set up and is free of compilers.

[ascl:1102.010]
SEREN: A SPH code for star and planet formation simulations

Hubber, David; Batty, Chris; McLeod, Andrew; Whitworth, Anthony; Bisbas, Thomas; Stamatellos, Dimitrios; Walch, Stefanie; Rawiraswattana, Krisada; Goodwin, Simon

SEREN is an astrophysical Smoothed Particle Hydrodynamics code designed to investigate star and planet formation problems using self-gravitating hydrodynamics simulations of molecular clouds, star-forming cores, and protostellar disks.

SEREN is written in Fortran 95/2003 with a modular philosophy for adding features into the code. Each feature can be easily activated or deactivated by way of setting options in the Makefile before compiling the code. This has the added benefit of allowing unwanted features to be removed at the compilation stage resulting in a smaller and faster executable program. SEREN is written with OpenMP directives to allow parallelization on shared-memory architecture.

[ascl:1404.005]
SER: Subpixel Event Repositioning Algorithms

Subpixel Event Repositioning (SER) techniques significantly improve the already unprecedented spatial resolution of Chandra X-ray imaging with the Advanced CCD Imaging Spectrometer (ACIS). Chandra CCD SER techniques are based on the premise that the impact position of events can be refined, based on the distribution of charge among affected CCD pixels. Unlike ACIS SER models that are restricted to corner split (3- and 4-pixel) events and assume that such events take place at the split pixel corners, this IDL code uses two-pixel splits as well, and incorporates more realistic estimates of photon impact positions.

[ascl:1811.004]
SEP: Source Extraction and Photometry

SEP (Source Extraction and Photometry) makes the core algorithms of Source Extractor (ascl:1010.064) available as a library of standalone functions and classes. These operate directly on in-memory arrays (no FITS files or configuration files). The code is derived from the Source Extractor code base (written in C) and aims to produce results compatible with Source Extractor whenever possible. SEP consists of a C library with no dependencies outside the standard library and a Python module that wraps the C library in a Pythonic API. The Python wrapper operates on NumPy arrays with NumPy as its only dependency. It is generated using Cython.

From Source Extractor, SEP includes background estimation, image segmentation (including on-the-fly filtering and source deblending), aperture photometry in circular and elliptical apertures, and source measurements such as Kron radius, "windowed" position fitting, and half-light radius. It also adds the following features that are not available in Source Extractor: optimized matched filter for variable noise in source extraction; circular annulus and elliptical annulus aperture photometry functions; local background subtraction in shape consistent with aperture in aperture photometry functions; exact pixel overlap mode in all aperture photometry functions; and masking of elliptical regions on images.

[ascl:1807.026]
SENR: Simple, Efficient Numerical Relativity

SENR (Simple, Efficient Numerical Relativity) provides the algorithmic framework that combines the C codes generated by NRPy+ (ascl:1807.025) into a functioning numerical relativity code. It is part of the numerical relativity code package SENR/NRPy+. The package extends previous implementations of the BSSN reference-metric formulation to a much broader class of curvilinear coordinate systems, making it suitable for modeling physical configurations with approximate or exact symmetries, such as modeling black hole dynamics.

[ascl:1504.009]
Self-lensing binary code with Markov chain

The self-lensing binary code with Markov chain code was used to analyze the self-lensing binary system KOI-3278. It includes the MCMC modeling and the key figures.

[ascl:1411.007]
segueSelect: SDSS/SEGUE selection function modelling

The Python package segueSelect automatically models the SDSS/SEGUE selection fraction -- the fraction of stars with good spectra -- as a continuous function of apparent magnitude for each plate. The selection function can be determined for any desired sample cuts in signal-to-noise ratio, u-g, r-i, and E(B-V). The package requires Pyfits (ascl:1207.009) and, for coordinate transformations, galpy (ascl:1411.008). It can calculate the KS probability that the spectropscopic sample was drawn from the underlying photometric sample with the model selection function, plot the cumulative distribution function in r-band apparent magnitude of the spectroscopic sample (red) and the photometric sample+selection-function-model for this plate, and, if galpy is installed, can transform velocities into the Galactic coordinate frame. The code can also determine the selection function for SEGUE K stars.

[ascl:1607.020]
SEEK: Signal Extraction and Emission Kartographer

Akeret, Joel; Seehars, Sebastian; Chang, Chihway; Monstein, Christian; Amara, Adam; Refregier, Alexandre

SEEK (Signal Extraction and Emission Kartographer) processes time-ordered-data from single dish radio telescopes or from the simulation pipline HIDE (ascl:1607.019), removes artifacts from Radio Frequency Interference (RFI), automatically applies flux calibration, and recovers the astronomical radio signal. With its companion code HIDE (ascl:1607.019), it provides end-to-end simulation and processing of radio survey data.

[ascl:1905.026]
SEDPY: Modules for storing and operating on astronomical source spectral energy distribution

SEDPY performs a variety of tasks for astronomical spectral energy distributions. It can generate synthetic photometry through any filter, provides detailed modeling of extinction curves, and offers basic aperture photometry algorithms. SEDPY can also store and interpolate model SEDs, convolve absolute or apparent fluxes, and calculate rest-frame magnitudes.

[ascl:1901.008]
SEDobs: Observational spectral energy distribution simulation

SEDobs uses state-of-the-art theoretical galaxy SEDs (spectral energy distributions) to create simulated observations of distant galaxies. It used BC03 and M05 theoretical models and allows the user to configure the simulated observation that are needed. For a given simulated galaxy, the user is able to simulate multi-spectral and multi-photometric observations.

[ascl:1101.001]
Second-order Tight-coupling Code

Prior to recombination photons, electrons, and atomic nuclei rapidly scattered and behaved, almost, like a single tightly-coupled photon-baryon plasma. In order to solve the cosmological perturbation equations during that time, Cosmic Microwave Background (CMB) codes use the so-called tight-coupling approximation in which the problematic terms (i.e. the source of the stiffness) are expanded in inverse powers of the Thomson Opacity. Most codes only keep the terms linear in the inverse Thomson Opacity. We have developed a second-order tight-coupling code to test the validity of the usual first-order tight-coupling code. It is based on the publicly available code CAMB.

[ascl:1201.003]
SeBa: Stellar and binary evolution

The stellar and binary evolution package SeBa is fully integrated into the kira integrator, although it can also be used as a stand-alone module for non-dynamical applications. Due to the interaction between stellar evolution and stellar dynamics, it is difficult to solve for the evolution of both systems in a completely self-consistent way. The trajectories of stars are computed using a block timestep scheme, as described earlier. Stellar and binary evolution is updated at fixed intervals (every 1/64 of a crossing time, typically a few thousand years). Any feedback between the two systems may thus experience a delay of at most one timestep. Internal evolution time steps may differ for each star and binary, and depend on binary period, perturbations due to neighbors, and the evolutionary state of the star. Time steps in this treatment vary from several milliseconds up to (at most) a million years.

[ascl:1210.012]
SearchCal: The JMMC Evolutive Search Calibrator Tool

SearchCal builds an evolutive catalog of stars suitable as calibrators within any given user-defined angular distance and magnitude around a scientific target. SearchCal can select suitable bright calibration stars (V ≤ 10; K ≤ 5.0) for obtaining the ultimate precision of current interferometric instruments like the VLTI and faint calibration stars up to K ~ 15 around the scientific target. Star catalogs available at the CDS are searched via web requests and provide the useful astrometric and photometric informations for selecting calibrators. The missing photometries are computed with an accuracy of about 0.1 mag. The stellar angular diameter is estimated with a precision of about 10% through newly determined surface-brightness versus color-index relations based on the I, J, H and K magnitudes. For each star the squared visibility is computed taking into account the central wavelength and the maximum baseline of the predicted observations.

[ascl:1601.003]
SCOUSE: Semi-automated multi-COmponent Universal Spectral-line fitting Engine

Henshaw, J. D.; Longmore, S. N.; Kruijssen, J. M. D.; Davies, B.; Bally, J.; Barnes, A.; Battersby, C.; Burton, M.; Cunningham, M. R.; Dale, J. E.; Ginsburg, A.; Immer, K.; Jones, P. A.; Kendrew, S.; Mills, E. A. C.; Molinari, S.; Moore, T. J. T.; Ott, J.; Pillai, T.; Rathborne, J.; Schilke, P.; Schmiedeke, A.; Testi, L.; Walker, D.; Walsh, A.; Zhang, Q.

The Semi-automated multi-COmponent Universal Spectral-line fitting Engine (SCOUSE) is a spectral line fitting algorithm that fits Gaussian files to spectral line emission. It identifies the spatial area over which to fit the data and generates a grid of spectral averaging areas (SAAs). The spatially averaged spectra are fitted according to user-provided tolerance levels, and the best fit is selected using the Akaike Information Criterion, which weights the chisq of a best-fitting solution according to the number of free-parameters. A more detailed inspection of the spectra can be performed to improve the fit through an iterative process, after which SCOUSE integrates the new solutions into the solution file.

[ascl:1609.006]
SCIMES: Spectral Clustering for Interstellar Molecular Emission Segmentation

SCIMES identifies relevant molecular gas structures within dendrograms of emission using the spectral clustering paradigm. It is useful for decomposing objects in complex environments imaged at high resolution.

[ascl:1311.001]
SciDB: Open Source DMAS for Scientific Research

SciDB is a DMAS (Data Management and Analytics Software System) optimized for data management of big data and for big analytics. SciDB is organized around multidimensional array storage, a generalization of relational tables, and is designed to be scalable up to petabytes and beyond. Complex analytics are simplified with SciDB because arrays and vectors are first-class objects with built-in optimized operations. Spatial operators and time-series analysis are easy to express. Interfaces to common scientific tools like R as well as programming languages like C++ and Python are provided.

[ascl:1907.001]
schwimmbad: Parallel processing pools interface

schwimmbad provides a uniform interface to parallel processing pools and enables switching easily between local development (e.g., serial processing or with multiprocessing) and deployment on a cluster or supercomputer (via, e.g., MPI or JobLib). The utilities provided by schwimmbad require that tasks or data be “chunked” and that code can be “mapped” onto the chunked tasks.

[ascl:1505.008]
SCEPtER: Stellar CharactEristics Pisa Estimation gRid

SCEPtER (Stellar CharactEristics Pisa Estimation gRid) estimates the stellar mass and radius given a set of observable quantities; the results are obtained by adopting a maximum likelihood technique over a grid of pre-computed stellar models. The code is quite flexible since different observables can be used, depending on their availability, as well as different grids of models.

[ascl:1803.003]
scarlet: Source separation in multi-band images by Constrained Matrix Factorization

Melchior, Peter; Moolekamp, Fred; Jerdee, Maximilian; Armstrong, Robert; Sun, Ai-Lei; Bosch, James; Lupton, Robert

SCARLET performs source separation (aka "deblending") on multi-band images. It is geared towards optical astronomy, where scenes are composed of stars and galaxies, but it is straightforward to apply it to other imaging data. Separation is achieved through a constrained matrix factorization, which models each source with a Spectral Energy Distribution (SED) and a non-parametric morphology, or multiple such components per source. The code performs forced photometry (with PSF matching if needed) using an optimal weight function given by the signal-to-noise weighted morphology across bands. The approach works well if the sources in the scene have different colors and can be further strengthened by imposing various additional constraints/priors on each source. Because of its generic utility, this package provides a stand-alone implementation that contains the core components of the source separation algorithm. However, the development of this package is part of the LSST Science Pipeline; the meas_deblender package contains a wrapper to implement the algorithms here for the LSST stack.

[ascl:1209.012]
Scanamorphos: Maps from scan observations made with bolometer arrays

Scanamorphos is an IDL program to build maps from scan observations made with bolometer arrays. Scanamorphos can post-process scan observations performed with the Herschel photometer arrays. This post-processing mainly consists in subtracting the total low-frequency noise (both its thermal and non-thermal components), masking cosmic ray hit residuals, and projecting the data onto a map. Although it was developed for Herschel, it is also applicable with minimal adjustment to scan observations made with other bolometer arrays provided they entail sufficient redundancy; it was successfully applied to P-Artemis, an instrument operating on the APEX telescope. Scanamorphos does not assume any particular noise model and does not apply any Fourier-space filtering to the data. It is an empirical tool using only the redundancy built in the observations, taking advantage of the fact that each portion of the sky is sampled at multiple times by multiple bolometers. The user is allowed to optionally visualize and control results at each intermediate step, but the processing is fully automated.

[ascl:1010.063]
SCAMP: Automatic Astrometric and Photometric Calibration

Astrometric and photometric calibrations have remained the most tiresome step in the reduction of large imaging surveys. SCAMP has been written to address this problem. The program efficiently computes accurate astrometric and photometric solutions for any arbitrary sequence of FITS images in a completely automatic way. SCAMP is released under the GNU General Public License.

[ascl:1904.015]
SBGAT: Small Bodies Geophysical Analysis Tool

SBGAT (Small Body Geophysical Analysis Tool) generates simulated data originating from small bodies shape models, combined with advanced shape-modification properties. It uses polyhedral shape models from which can be computed mass properties such as volume, center of mass, and inertia, synthetic observations such as lightcurves and radar, and which can be used within dynamical models, such as spherical harmonics and polyhedron gravity modeling. SBGAT can generate spherical harmonics expansions from constant-density polyhedra (and export them to JSON) and evaluate the spherical harmonics expansions. It can also generate YORP coefficients, multi-threaded Polyhedron Gravity Model gravity and potential evaluations, and synthetic light-curve and radar observations for single/primary asteroids.

SBGAT has two distinct packages: a dynamic library SBGAT Core that contains the data structure and algorithm backbone of SBGAT, and SBGAT Gui, which wraps the former inside a VTK, Qt user interface to facilitate user/data interaction. SBGAT Core can be used without the SBGAT Gui wrapper.

[ascl:1601.012]
SavGolFilterCov: Savitzky Golay filter for data with error covariance

A Savitzky–Golay filter is often applied to data to smooth the data without greatly distorting the signal; however, almost all data inherently comes with noise, and the noise properties can differ from point to point. This python script improves upon the traditional Savitzky-Golay filter by accounting for error covariance in the data. The inputs and arguments are modeled after scipy.signal.savgol_filter.

[ascl:1309.005]
SATMC: SED Analysis Through Monte Carlo

SATMC is a general purpose, MCMC-based SED fitting code written for IDL and Python. Following Bayesian statistics and Monte Carlo Markov Chain algorithms, SATMC derives the best fit parameter values and returns the sampling of parameter space used to construct confidence intervals and parameter-parameter confidence contours. The fitting may cover any range of wavelengths. The code is designed to incorporate any models (and potential priors) of the user's choice. The user guide lists all the relevant details for including observations, models and usage under both IDL and Python.

[ascl:1707.002]
SASRST: Semi-Analytic Solutions for 1-D Radiative Shock Tubes

SASRST, a small collection of Python scripts, attempts to reproduce the semi-analytical one-dimensional equilibrium and non-equilibrium radiative shock tube solutions of Lowrie & Rauenzahn (2007) and Lowrie & Edwards (2008), respectively. The included code calculates the solution for a given set of input parameters and also plots the results using Matplotlib. This software was written to provide validation for numerical radiative shock tube solutions produced by a radiation hydrodynamics code.

[ascl:1404.004]
SAS: Science Analysis System for XMM-Newton observatory

The Science Analysis System (SAS) is an extensive suite of software tasks developed to process the data collected by the XMM-Newton Observatory. The SAS extracts standard (spectra, light curves) and/or customized science products, and allows reproductions of the reduction pipelines run to get the PPS products from the ODFs files. SAS includes a powerful and extensive suite of FITS file manipulation packages based on the Data Access Layer library.

[ascl:1904.020]
SARAH: SUSY and non-SUSY model builder and analyzer

SARAH builds and analyzes SUSY and non-SUSY models. It calculates all vertices, mass matrices, tadpoles equations, one-loop corrections for tadpoles and self-energies, and two-loop RGEs for a given model. SARAH writes model files for a variety of other software packages for dark matter studies, includes many SUSY and non-SUSY models, and makes implementing new models efficient and straightforward. Written in Mathematica, SARAH can also use output from Vevacious (ascl:1904.019) to check for the global minimum for a given model and parameter point.

[ascl:1907.005]
SARA-PPD: Preconditioned primal-dual algorithm for radio-interferometric imaging

SARA-PPD is a proof of concept MATLAB implementation of an acceleration strategy for a recently proposed primal-dual distributed algorithm. The algorithm optimizes resolution by accounting for the correct noise statistics, leverages natural weighting in the definition of the minimization problem for image reconstruction, and optimizes sensitivity by enabling accelerated convergence through a preconditioning strategy incorporating sampling density information. This algorithm offers efficient processing of large-scale data sets that will be acquired by next generation radio-interferometers such as the Square Kilometer Array.

[ascl:1210.029]
Sapporo: N-body simulation library for GPUs

Sapporo mimics the behavior of GRAPE hardware and uses the GPU to perform high-precision gravitational N-body simulations. It makes use of CUDA and therefore only works on NVIDIA GPUs. N-body codes currently running on GRAPE-6 can switch to Sapporo by a simple relinking of the library. Sapporo's precision is comparable to that of GRAPE-6, even though internally the GPU hardware is limited to single precision arithmetics. This limitation is effectively overcome by emulating double precision for calculating the distance between particles.

[ascl:0003.002]
SAOImage DS9: A utility for displaying astronomical images in the X11 window environment

SAOImage DS9 is an astronomical imaging and data visualization application. DS9 supports FITS images and binary tables, multiple frame buffers, region manipulation, and many scale algorithms and colormaps. It provides for easy communication with external analysis tasks and is highly configurable and extensible via XPA and SAMP. DS9 is a stand-alone application. It requires no installation or support files. Versions of DS9 currently exist for Solaris, Linux, MacOSX, and Windows. All versions and platforms support a consistent set of GUI and functional capabilities. DS9 supports advanced features such as multiple frame buffers, mosaic images, tiling, blinking, geometric markers, colormap manipulation, scaling, arbitrary zoom, rotation, pan, and a variety of coordinate systems. DS9 also supports FTP and HTTP access. The GUI for DS9 is user configurable. GUI elements such as the coordinate display, panner, magnifier, horizontal and vertical graphs, button bar, and colorbar can be configured via menus or the command line. DS9 is a Tk/Tcl application which utilizes the SAOTk widget set. It also incorporates the X Public Access (XPA) mechanism to allow external processes to access and control its data, GUI functions, and algorithms.

[ascl:1605.015]
SAND: Automated VLBI imaging and analyzing pipeline

The Search And Non-Destroy (SAND) is a VLBI data reduction pipeline composed of a set of Python programs based on the AIPS interface provided by ObitTalk. It is designed for the massive data reduction of multi-epoch VLBI monitoring research. It can automatically investigate calibrated visibility data, search all the radio emissions above a given noise floor and do the model fitting either on the CLEANed image or directly on the uv data. It then digests the model-fitting results, intelligently identifies the multi-epoch jet component correspondence, and recognizes the linear or non-linear proper motion patterns. The outputs including CLEANed image catalogue with polarization maps, animation cube, proper motion fitting and core light curves. For uncalibrated data, a user can easily add inline modules to do the calibration and self-calibration in a batch for a specific array.

[ascl:1504.011]
samiDB: A Prototype Data Archive for Big Science Exploration

samiDB is an archive, database, and query engine to serve the spectra, spectral hypercubes, and high-level science products that make up the SAMI Galaxy Survey. Based on the versatile Hierarchical Data Format (HDF5), samiDB does not depend on relational database structures and hence lightens the setup and maintenance load imposed on science teams by metadata tables. The code, written in Python, covers the ingestion, querying, and exporting of data as well as the automatic setup of an HTML schema browser. samiDB serves as a maintenance-light data archive for Big Science and can be adopted and adapted by science teams that lack the means to hire professional archivists to set up the data back end for their projects.

[ascl:1407.006]
SAMI: Sydney-AAO Multi-object Integral field spectrograph pipeline

Allen, J. T.; Green, A. W.; Fogarty, L. M. R.; Sharp, R.; Nielsen, J.; Konstantopoulos, I.; Taylor, E. N.; Scott, N.; Cortese, L.; Richards, S. N.; Croom, S.; Owers, M. S.; Bauer, A. E.; Sweet, S. M.; Bryant, J. J.

The SAMI (Sydney-AAO Multi-object Integral field spectrograph) pipeline reduces data from the Sydney-AAO Multi-object Integral field spectrograph (SAMI) for the SAMI Galaxy Survey. The python code organizes SAMI data and, along with the AAO 2dfdr package, carries out all steps in the data reduction, from raw data to fully calibrated datacubes. The principal steps are: data management, use of 2dfdr to produce row-stacked spectra, flux calibration, correction for telluric absorption, removal of atmospheric dispersion, alignment of dithered exposures, and drizzling onto a regular output grid. Variance and covariance information is tracked throughout the pipeline. Some quality control routines are also included.

[ascl:1203.011]
SALT2: Spectral Adaptive Lightcurve Template

SALT (Spectral Adaptive Lightcurve Template) is a package for Type Ia Supernovae light curve fitting. Its main purpose is to provide a distance estimator but it can also be used for photometric redshifts, and spectroscopic + photometric identification. This code is also known by the name snfit.

[ascl:1601.006]
SAGE: Semi-Analytic Galaxy Evolution

Croton, Darren J.; Stevens, Adam R. H.; Tonini, Chiara; Garel, Thibault; Bernyk, Maksym; Bibiano, Antonio; Hodkinson, Luke; Mutch, Simon J.; Poole, Gregory B.; Shattow, Genevieve M.

SAGE (Semi-Analytic Galaxy Evolution) models galaxy formation in a cosmological context. SAGE has been rebuilt to be modular and customizable. The model runs on any dark matter cosmological N-body simulation whose trees are organized in a supported format and contain a minimum set of basic halo properties.

[submitted]
Sacc: Save All Correlations and Covariances

Zuntz, J.; Slosar, A.; Alonso, D.; Becker, M.; Broussard, A.; McClintock, T.; Nicola, A.; Miyatake, H.; Sanchez, J.; Neveu, J.

SACC (Save All Correlations and Covariances) is a format and reference library for general storage

of summary statistic measurements for the Dark Energy Science Collaboration (DESC) within and from the Large Synoptic Survey Telescope (LSST) project's Dark Energy Science Collaboration.

[ascl:1306.001]
SAC: Sheffield Advanced Code

The Sheffield Advanced Code (SAC) is a fully non-linear MHD code designed for simulations of linear and non-linear wave propagation in gravitationally strongly stratified magnetized plasma. It was developed primarily for the forward modelling of helioseismological processes and for the coupling processes in the solar interior, photosphere, and corona; it is built on the well-known VAC platform that allows robust simulation of the macroscopic processes in gravitationally stratified (non-)magnetized plasmas. The code has no limitations of simulation length in time imposed by complications originating from the upper boundary, nor does it require implementation of special procedures to treat the upper boundaries. SAC inherited its modular structure from VAC, thereby allowing modification to easily add new physics.

[ascl:1111.003]
Saada: A Generator of Astronomical Database

Saada transforms a set of heterogeneous FITS files or VOtables of various categories (images, tables, spectra, etc.) in a powerful database deployed on the Web. Databases are located on your host and stay independent of any external server. This job doesn’t require writing code. Saada can mix data of various categories in multiple collections. Data collections can be linked each to others making relevant browsing paths and allowing data-mining oriented queries. Saada supports 4 VO services (Spectra, images, sources and TAP) . Data collections can be published immediately after the deployment of the Web interface.

[ascl:1103.003]
S2PLOT: Three-dimensional (3D) Plotting Library

We present a new, three-dimensional (3D) plotting library with advanced features, and support for standard and enhanced display devices. The library - S2PLOT - is written in C and can be used by C, C++ and FORTRAN programs on GNU/Linux and Apple/OSX systems. S2PLOT draws objects in a 3D (x,y,z) Cartesian space and the user interactively controls how this space is rendered at run time. With a PGPLOT inspired interface, S2PLOT provides astronomers with elegant techniques for displaying and exploring 3D data sets directly from their program code, and the potential to use stereoscopic and dome display devices. The S2PLOT architecture supports dynamic geometry and can be used to plot time-evolving data sets, such as might be produced by simulation codes. In this paper, we introduce S2PLOT to the astronomical community, describe its potential applications, and present some example uses of the library.

[ascl:1211.001]
S2LET: Fast wavelet analysis on the sphere

S2LET provides high performance routines for fast wavelet analysis of signals on the sphere. It uses the SSHT code built on the MW sampling theorem to perform exact spherical harmonic transforms on the sphere. The resulting wavelet transform implemented in S2LET is theoretically exact, i.e. a band-limited signal can be recovered from its wavelet coefficients exactly and the wavelet coefficients capture all the information. S2LET also supports the HEALPix sampling scheme, in which case the transforms are not theoretically exact but achieve good numerical accuracy. The core routines of S2LET are written in C and have interfaces in Matlab, IDL and Java. Real signals can be written to and read from FITS files and plotted as Mollweide projections.

[ascl:1110.013]
S2HAT: Scalable Spherical Harmonic Transform Library

Many problems in astronomy and astrophysics require a computation of the spherical harmonic transforms. This is in particular the case whenever data to be analyzed are distributed over the sphere or a set of corresponding mock data sets has to be generated. In many of those contexts, rapidly improving resolutions of both the data and simulations puts increasingly bigger emphasis on our ability to calculate the transforms quickly and reliably.

The scalable spherical harmonic transform library S2HAT consists of a set of flexible, massively parallel, and scalable routines for calculating diverse (scalar, spin-weighted, etc) spherical harmonic transforms for a class of isolatitude sky grids or pixelizations. The library routines implement the standard algorithm with the complexity of O(n^3/2), where n is a number of pixels/grid points on the sphere, however, owing to their efficient parallelization and advanced numerical implementation, they achieve very competitive performance and near perfect scalability. S2HAT is written in Fortran 90 with a C interface. This software is a derivative of the spherical harmonic transforms included in the HEALPix package and is based on both serial and MPI routines of its version 2.01, however, since version 2.5 this software is fully autonomous of HEALPix and can be compiled and run without the HEALPix library.

[ascl:1606.008]
s2: Object oriented wrapper for functions on the sphere

The s2 package can represent any arbitrary function defined on the sphere. Both real space map and harmonic space spherical harmonic representations are supported. Basic sky representations have been extended to simulate full sky noise distributions and Gaussian cosmic microwave background realisations. Support for the representation and convolution of beams is also provided. The code requires HEALPix (ascl:1107.018) and CFITSIO (ascl:1010.001).

[ascl:1907.013]
RVSpecFit: Radial velocity and stellar atmospheric parameter fitting

RVSpecFit determines radial velocities and stellar atmospheric parameters from spectra by direct pixel fitting by interpolated stellar templates. The code doesn't require spectrum normalization and can deal with non-flux calibrated spectra. RVSpecFit is able to fit multiple spectra simultaneously.

[ascl:9912.003]
RVSAO 2.0: Digital Redshifts and Radial Velocities

RVSAO is a set of programs to obtain redshifts and radial velocities from digital spectra. RVSAO operates in the IRAF (Tody 1986, 1993) environment. The heart of the system is xcsao, which implements the cross-correlation method, and is a direct descendant of the system built by Tonry and Davis (1979). emsao uses intelligent heuristics to search for emission lines in spectra, then fits them to obtain a redshift. sumspec shifts and sums spectra to build templates for cross-correlation. linespec builds synthetic spectra given a list of spectral lines. bcvcorr corrects velocities for the motion of the earth. We discuss in detail the parameters necessary to run xcsao and emsao properly. We discuss the reliability and error associated with xcsao derived redshifts. We develop an internal error estimator, and we show how large, stable surveys can be used to develop more accurate error estimators. We develop a new methodology for building spectral templates for galaxy redshifts. We show how to obtain correlation velocities using emission line templates. Emission line correlations are substantially more efficient than the previous standard technique, automated emission line fitting. We compare the use of RVSAO with new methods, which use Singular Value Decomposition and $chi^2$ fitting techniques.

[ascl:1210.031]
RVLIN: Fitting Keplerian curves to radial velocity data

The RVLIN package for IDL is a set of routines that quickly fits an arbitrary number of Keplerian curves to radial velocity data. It can handle data from multiple telescopes (i.e. it solves for the offset), constraints on P, e, and time of peri passage, and can incorporate transit timing data. The code handles fixed periods and circular orbits in combination and transit time constraints, including for multiple transiting planets.

[ascl:1505.020]
rvfit: Radial velocity curves fitting for binary stars or exoplanets

rvfit, developed in IDL 7.0, fits non-precessing keplerian radial velocity (RV) curves for double-line and single-line binary stars or exoplanets. It fits a simple keplerian model to the observed RV and computes the seven parameters (six for a single-line system) from the model. Some parameters can be fixed beforehand if they are known, for instance, if photometric observations are available. The fit is done using an Adaptive Simulated Annealing algorithm optimized for this specific task. Simulated Annealing methods are powerful heuristic algorithms to minimize functions in multiparametric spaces.

[ascl:1406.007]
RV: Radial Components of Observer's Velocity

The RV program produces a report listing the components, in a given direction, of the observer's velocity on a given date. This allows an observed radial velocity to be referred to an appropriate standard of rest -- typically either the Sun or an LSR.

As a secondary function, RV computes light time components to the Sun, thus allowing the times of phenomena observed from a terrestrial observatory to be referred to a heliocentric frame of reference. n.b. It will of course, in addition, be necessary to express the observations in the appropriate timescale as well as applying light time corrections. In particular, it is likely that an observed UTC will need to be converted to TDB as well as being corrected to the Sun.)

RV is distributed with the Starlink software collection (ascl:1110.012) and uses SLALIB (ascl:1403.025).

[ascl:1802.011]
runDM: Running couplings of Dark Matter to the Standard Model

runDM calculates the running of the couplings of Dark Matter (DM) to the Standard Model (SM) in simplified models with vector mediators. By specifying the mass of the mediator and the couplings of the mediator to SM fields at high energy, the code can calculate the couplings at low energy, taking into account the mixing of all dimension-6 operators. runDM can also extract the operator coefficients relevant for direct detection, namely low energy couplings to up, down and strange quarks and to protons and neutrons.

[ascl:1706.002]
rtpipe: Searching for Fast Radio Transients in Interferometric Data

rtpipe (real-time pipeline) analyzes radio interferometric data with an emphasis on searching for transient or variable astrophysical sources. The package combines single-dish concepts such as dedispersion and filters with interferometric concepts, including images and the uv-plane. In contrast to time-domain data recorded with large single-dish telescopes, visibilities from interferometers can precisely localize sources anywhere in the entire field of view. rtpipe opens interferometers to the study of fast transient sky, including sources like pulsars, stellar flares, rotating radio transients, and fast radio bursts. Key portions of the search pipeline, such as image generation and dedispersion, have been accelerated. That, in combination with its multi-threaded, multi-node design, makes rtpipe capable of searching millisecond timescale data in real time on small compute clusters.

[ascl:1607.015]
RT1D: 1D code for Rayleigh-Taylor instability

The parallel one-dimensional moving-mesh hydrodynamics code RT1D reproduces the multidimensional dynamics from Rayleigh-Taylor instability in supernova remnants.

[ascl:1808.002]
rsigma: Resonant disturbance

rsigma calculates the resonant disturbing function, R(sigma), for a massless particle in an arbitrary orbit perturbed by a planet in circular orbit. This function defines the strength of the resonance (its semi-amplitude) and the location of the stable equilibrium points (the minima). It depends on the variable sigma called critical angle and on the particle's orbital elements a, e, i and the argument of the perihelion. R(sigma) is numerically calculated and the code is valid for arbitrary eccentricities and inclinations, including retrograde orbits.

[ascl:1905.015]
rPICARD: Radboud PIpeline for the Calibration of high Angular Resolution Data

rPICARD (Radboud PIpeline for the Calibration of high Angular Resolution Data) reduces data from different VLBI arrays, including high-frequency and low-sensitivity arrays, and supports continuum, polarization, and phase-referencing observations. Built on the CASA (ascl:1107.013) framework, it uses CASA for CLEAN imaging and self-calibration, and can be run non-interactively after only a few non-default input parameters are set. rPICARD delivers high-quality calibrated data and large bandwidth data can be processed within reasonable computing times.

[ascl:1902.006]
RPFITS: Routines for reading and writing RPFITS files

Norris, Ray; Calabretta, Mark; Wieringa, Mark; Hunt, A.J.; May, H.; Killeen, N.; Sault, R.; Wilson, Warwick; Kesteven, Michael

The RPFITS data file format records synthesis visibility data obtained from the Australia Telescope Compact Array (ATCA) at Narrabri, NSW. It is also used for single-dish spectral line data obtained from Parkes and Mopra, including Parkes multibeam data. RPFITS superficially resembles random group FITS, but differs in important respects, making it incompatible with standard FITS software such as FITSIO (ascl:1010.001) and FTOOLS (ascl:9912.002) and, in particular, it precludes the use of fv (ascl:1205.005). The RPFITS Fortran library contains routines for reading and writing RPFITS files. A header file, RPFITS.h, is provided to facilitate usage by C and C++ applications. Also included is rpfhdr, a utility for viewing RPFITS headers (it also works for standard FITS), and rpfex for extracting selected scans from an RPFITS file.

[ascl:1712.009]
RODRIGUES: RATT Online Deconvolved Radio Image Generation Using Esoteric Software

RODRIGUES (RATT Online Deconvolved Radio Image Generation Using Esoteric Software) is a web-based radio telescope simulation and reduction tool. From a technical perspective it is a web based parameterized docker container scheduler with a result set viewer.

[ascl:1210.008]
Rockstar: Phase-space halo finder

Rockstar (Robust Overdensity Calculation using K-Space Topologically Adaptive Refinement) identifies dark matter halos, substructure, and tidal features. The approach is based on adaptive hierarchical refinement of friends-of-friends groups in six phase-space dimensions and one time dimension, which allows for robust (grid-independent, shape-independent, and noise-resilient) tracking of substructure. Our method is massively parallel (up to 10^5 CPUs) and runs on the largest current simulations (>10^10 particles) with high efficiency (10 CPU hours and 60 gigabytes of memory required per billion particles analyzed). Rockstar offers significant improvement in substructure recovery as compared to several other halo finders.

[ascl:1201.002]
Roche: Visualization and analysis tool for Roche-lobe geometry of evolving binaries

Roche is a visualization and analysis tool for drawing the Roche-lobe geometry of evolving binaries. Roche can be used as a standalone program reading data from the command line or from a file generated by SeBa (ascl:1201.003). Eventually Roche will be able to read data from any other binary evolution program. Roche requires Starlab (ascl:1010.076) version 4.1.1 or later and the pgplot (ascl:1103.002) libraries. Roche creates a series of images, based on the SeBa output file SeBa.data, displaying the evolutionary state of a binary.

[ascl:1502.023]
ROBOSPECT: Width fitting program

ROBOSPECT, written in C, automatically measures and deblends line equivalent widths for absorption and emission spectra. ROBOSPECT should not be used for stars with spectra in which there is no discernible continuum over large wavelength regions, nor for the most carbon-enhanced stars for which spectral synthesis would be favored. Although ROBOSPECT was designed for metal-poor stars, it is capable of fitting absorption and emission features in a variety of astronomical sources.

[ascl:1808.011]
Robbie: Radio transients and variables detection workflow

Robbie automates cataloging sources, finding variables, and identifying transients in the image domain. It works in a batch processing paradigm with a modular design so components can be swapped out or upgraded to adapt to different input data while retaining a consistent and coherent methodological approach. Robbie is based on commonly used and open software, including AegeanTools (ascl:1212.009) and STILS/TOPCAT (ascl:1101.010).

[ascl:1603.008]
ROBAST: ROOT-based ray-tracing library for cosmic-ray telescopes

ROBAST (ROOT-based simulator for ray tracing) is a non-sequential ray-tracing simulation library developed for wide use in optical simulations of gamma-ray and cosmic-ray telescopes. The library is written in C++ and fully utilizes the geometry library of the ROOT analysis framework, and can build the complex optics geometries typically used in cosmic ray experiments and ground-based gamma-ray telescopes.

[ascl:1104.008]
Rmodel: Determining Stellar Population Parameters

This program determines stellar population parameters (e.g. age, metallicity, IMF slope,...), using as input a pair of line-strength indices, through the interpolation in SSP model predictions. Both linear and bivariate fits are computed to perform the interpolation.

[ascl:1403.011]
RMHB: Hierarchical Reverberation Mapping

RMHB is a hierarchical Bayesian code for reverberation mapping (RM) that combines results of a sparsely sampled broad line region (BLR) light curve and a large sample of active galactic nuclei (AGN) to infer properties of the sample of the AGN. The key idea of RM is to measure the time lag τ between variations in the continuum emission from the accretion disc and subsequent response of the broad line region (BLR). The measurement of τ is typically used to estimate the physical size of the BLR and is combined with other measurements to estimate the black hole mass MBH. A major difficulty with RM campaigns is the large amount of data needed to measure τ. RMHB allows a clear interpretation of a posterior distribution for hyperparameters describing the sample of AGN.

[ascl:1409.011]
rmfit: Forward-folding spectral analysis software

Rmfit uses a forward-folding technique to obtain the best-fit parameters for a chosen model given user-selected source and background time intervals from data files containing observed count rates and a corresponding detector response matrix. rmfit displays lightcurves and spectra using a graphical interface that enables user-defined integrated or time-resolved spectral fits and binning in either time or energy. Originally developed for the analysis of BATSE Gamma-Ray Burst (GRB) spectroscopy, rmfit is a tool for the spectroscopy of transient sources; it accommodates the Fermi GBM and LAT data and Swift BAT.

[ascl:1806.024]
RMextract: Ionospheric Faraday Rotation calculator

RMextract calculates Ionospheric Faraday Rotation for a given epoch, location and line of sight. This Python code extracts TEC, vTEC, Earthmagnetic field and Rotation Measures from GPS and WMM data for radio interferometry observations.

[ascl:1708.011]
RM-CLEAN: RM spectra cleaner

RM-CLEAN reads in dirty Q and U cubes, generates rmtf based on the frequencies given in an ASCII file, and cleans the RM spectra following the algorithm given by Brentjens (2007). The output cubes contain the clean model components and the CLEANed RM spectra. The input cubes must be reordered with mode=312, and the output cubes will have the same ordering and thus must be reordered after being written to disk. RM-CLEAN runs as a MIRIAD (ascl:1106.007) task and a Python wrapper is included with the code.

[ascl:1811.009]
RLOS: Time-resolved imaging of model astrophysical jets

RLOS (Relativistic Line Of Sight) uses hydrocode output data, such as that from PLUTO (ascl:1010.045), to create synthetic images depicting what a model relativistic astrophysical jet looks like to a stationary observer. The approximate time-delayed imaging algorithm used is implemented within existing line-of-sight code. The software has the potential to study a variety of dynamical astrophysical phenomena in collaboration with other imaging and simulation tools.

[ascl:1410.005]
RICH: Numerical simulation of compressible hydrodynamics on a moving Voronoi mesh

RICH (Racah Institute Computational Hydrodynamics) is a 2D hydrodynamic code based on Godunov's method. The code, largely based on AREPO, acts on an unstructured moving mesh. It differs from AREPO in the interpolation and time advancement scheme as well as a novel parallelization scheme based on Voronoi tessellation. Though not universally true, in many cases a moving mesh gives better results than a static mesh: where matter moves one way and a sound wave is traveling in the other way (such that relative to the grid the wave is not moving), a static mesh gives better results than a moving mesh. RICH is designed in an object oriented, user friendly way that facilitates incorporation of new algorithms and physical processes.

[ascl:1611.009]
RHOCUBE: 3D density distributions modeling code

RHOCUBE models 3D density distributions on a discrete Cartesian grid and their integrated 2D maps. It can be used for a range of applications, including modeling the electron number density in LBV shells and computing the emission measure. The RHOCUBE Python package provides several 3D density distributions, including a powerlaw shell, truncated Gaussian shell, constant-density torus, dual cones, and spiralling helical tubes, and can accept additional distributions. RHOCUBE provides convenient methods for shifts and rotations in 3D, and if necessary, an arbitrary number of density distributions can be combined into the same model cube and the integration ∫ d*z* performed through the joint density field.

[ascl:1502.001]
RH 1.5D: Polarized multi-level radiative transfer with partial frequency distribution

RH 1.5D performs Zeeman multi-level non-local thermodynamical equilibrium calculations with partial frequency redistribution for an arbitrary amount of chemical species. Derived from the RH code and written in C, it calculates spectra from 3D, 2D or 1D atmospheric models on a column-by-column basis (or 1.5D). It includes optimization features to speed up or improve convergence, which are particularly useful in dynamic models of chromospheres. While one should be aware of its limitations, the calculation of spectra using the 1.5D or column-by-column is a good approximation in many cases, and generally allows for faster convergence and more flexible methods of improving convergence. RH 1.5D scales well to at least tens of thousands of CPU cores.

[ascl:1711.006]
RGW: Goodman-Weare Affine-Invariant Sampling

RGW is a lightweight R-language implementation of the affine-invariant Markov Chain Monte Carlo sampling method of Goodman & Weare (2010). The implementation is based on the description of the python package emcee (ascl:1303.002).

[ascl:1710.002]
rfpipe: Radio interferometric transient search pipeline

rfpipe supports Python-based analysis of radio interferometric data (especially from the Very Large Array) and searches for fast radio transients. This extends on the rtpipe library (ascl:1706.002) with new approaches to parallelization, acceleration, and more portable data products. rfpipe can run in standalone mode or be in a cluster environment.

[ascl:1505.028]
RESOLVE: Bayesian algorithm for aperture synthesis imaging in radio astronomy

RESOLVE is a Bayesian inference algorithm for image reconstruction in radio interferometry. It is optimized for extended and diffuse sources. Features include parameter-free Bayesian reconstruction of radio continuum data with a focus on extended and weak diffuse sources, reconstruction with uncertainty propagation dependent on measurement noise, and estimation of the spatial correlation structure of the radio astronomical source. RESOLVE provides full support for measurement sets and includes a simulation tool (if uv-coverage is provided).

[ascl:1809.016]
RequiSim: Variance weighted overlap calculator

RequiSim computes the Variance Weighted Overlap, which is a measure of the bias on the lensing signal from power spectrum modelling bias for any non-linear model. It assumes that the bias on the power spectrum is Gaussian with a covariance described by a user-provided knowledge matrix that describes the covariance in the bias on the power spectrum. The data from the Euclid wide-field survey are included.

[ascl:1612.022]
REPS: REscaled Power Spectra for initial conditions with massive neutrinos

Zennaro, Matteo; Bel, Julien; Villaescusa-Navarro, Francisco; Carbone, Carmelita; Sefusatti, Emiliano; Guzzo, Luigi

REPS (REscaled Power Spectra) provides accurate, one-percent level, numerical simulations of the initial conditions for massive neutrino cosmologies, rescaling the late-time linear power spectra to the simulation initial redshift.

[ascl:1904.008]
repack: Repack and compress line-transition data

repack re-packs and compresses line-transition data for radiative-transfer calculations. It identifies the strong lines that dominate the spectrum from the large-majority of weaker lines, returning a binary line-by-line (LBL) file with the strong lines info (wavenumber, Elow, gf, and isotope ID), and an ASCII file with the combined contribution of the weaker lines compressed into a continuum extinction coefficient (in cm-1 amagat-1) as function of wavenumber and temperature.

[ascl:1505.021]
relline: Relativistic line profiles calculation

relline calculates relativistic line profiles; it is compatible with the common X-ray data analysis software XSPEC (ascl:9910.005) and ISIS (ascl:1302.002). The two basic forms are an additive line model (RELLINE) and a convolution model to calculate relativistic smearing (RELCONV).

[ascl:1404.012]
RegPT: Regularized cosmological power spectrum

RegPT computes the power spectrum in flat wCDM class models based on the RegPT treatment when provided with either of transfer function or matter power spectrum. It then gives the multiple-redshift outputs for power spectrum, and optionally provides correlation function data. The Fortran code has two major options for power spectrum calculations; -fast, which quickly computes the power spectrum at two-loop level (typically a few seconds) using the pre-computed data set of PT kernels for fiducial cosmological models, and -direct, in which the code first applies the fast method, and then follows the regularized expression for power spectrum to directly evaluate the multi-dimensional integrals. The output results are the power spectrum of direct calculation and difference of the results between fast and direct method. The code also gives the data set of PT diagrams necessary for power spectrum calculations from which the power spectrum can be constructed.

[ascl:1206.001]
RegiStax: Alignment, stacking and processing of images

Berrevoets, Cor; DeClerq, Bart; George, Tony; Makolkin, Dmitry; Maxson, Paul; Pilz, Bob; Presnyakov, Pavel; Roel, Eric; Weiller, Sylvain

RegiStax is software for alignment/stacking/processing of images; it was released over 10 years ago and continues to be developed and improved. The current version is RegiStax 6, which supports the following formats: AVI, SER, RFL (RegiStax Framelist), BMP, JPG, TIF, and FIT. This version has a shorter and simpler processing sequence than its predecessor, and optimizing isn't necessary anymore as a new image alignment method optimizes directly. The interface of RegiStax 6 has been simplified to look more uniform in appearance and functionality, and RegiStax 6 now uses Multi-core processing, allowing the user to have up to have multiple cores(recommended to use maximally 4) working simultaneous during alignment/stacking.

[ascl:1401.004]
Reflex: Graphical workflow engine for data reduction

Reflex provides an easy and flexible way to reduce VLT/VLTI science data using the ESO pipelines. It allows graphically specifying the sequence in which the data reduction steps are executed, including conditional stops, loops and conditional branches. It eases inspection of the intermediate and final data products and allows repetition of selected processing steps to optimize the data reduction. The data organization necessary to reduce the data is built into the system and is fully automatic; advanced users can plug their own modules and steps into the data reduction sequence. Reflex supports the development of data reduction workflows based on the ESO Common Pipeline Library. Reflex is based on the concept of a scientific workflow, whereby the data reduction cascade is rendered graphically and data seamlessly flow from one processing step to the next. It is distributed with a number of complete test datasets so users can immediately start experimenting and familiarize themselves with the system.

[ascl:1508.003]
REDUCEME: Long-slit spectroscopic data reduction and analysis

Cardiel, N; Gorgas, J.; Pedraz, S.; Cenarro, J.; Alonso, O; Gil de Paz, A.; García-Dabó, E.; Sánchez-Blázquez, P.; Mármol-Queraltó, E.; Toloba, E.

The astronomical data reduction package REDUCEME reduces and analyzes long-slit spectroscopic data. The package uses the unformatted FORTRAN raw data format, so requires FITS files be transformed to REDUCEME format; the reverse operation (from REDUCEME to FITS format) is also available. The package is a set of programs written in FORTRAN 77 and includes shell scripts (using the C shell syntax) to perform routine tasks; it can be extended by the inclusion of external programs. REDUCEME uses PGPLOT (ascl:1103.002) for line plots and images, and a subset of subroutines, called BUTTON, enables the user to communicate interactively with the image display employing graphic buttons. One advantage of using REDUCEME is that for each image an associated error image can also be processed throughout the reduction process, allowing for a careful control of the error propagation.

[ascl:1507.017]
REDSPEC: NIRSPEC data reduction

REDSPEC is an IDL based reduction package designed with NIRSPEC in mind though can be used to reduce data from other spectrographs as well. REDSPEC accomplishes spatial rectification by summing an *A+B* pair of a calibration star to produce an image with two spectra; the image is remapped on the basis of polynomial fits to the spectral traces and calculation of gaussian centroids to define their separation, producing straight spectral traces with respect to the detector rows. The raw images are remapped onto a coordinate system with uniform intervals in spatial extent along the slit and in wavelength along the dispersion axis.

[ascl:1106.026]
RECFAST: Calculate the Recombination History of the Universe

RECFAST calculates the recombination of H, HeI, and HeII in the early Universe; this involves a line-by-line treatment of each atomic level. It differs in comparison to previous calculations in two major ways: firstly, the ionization fraction x_e is approximately 10% smaller for redshifts <~800, due to non-equilibrium processes in the excited states of H, and secondly, HeI recombination is much slower than previously thought, and is delayed until just before H recombines. RECFAST enables fast computation of the ionization history (and quantities such as the power spectrum of CMB anisotropies which depend on it) for arbitrary cosmologies.

[ascl:1110.016]
REBOUND: Multi-purpose N-body code for collisional dynamics

REBOUND is a multi-purpose N-body code which is freely available under an open-source license. It was designed for collisional dynamics such as planetary rings but can also solve the classical N-body problem. It is highly modular and can be customized easily to work on a wide variety of different problems in astrophysics and beyond.

REBOUND comes with three symplectic integrators: leap-frog, the symplectic epicycle integrator (SEI) and a Wisdom-Holman mapping (WH). It supports open, periodic and shearing-sheet boundary conditions. REBOUND can use a Barnes-Hut tree to calculate both self-gravity and collisions. These modules are fully parallelized with MPI as well as OpenMP. The former makes use of a static domain decomposition and a distributed essential tree. Two new collision detection modules based on a plane-sweep algorithm are also implemented. The performance of the plane-sweep algorithm is superior to a tree code for simulations in which one dimension is much longer than the other two and in simulations which are quasi-two dimensional with less than one million particles.

[ascl:1107.009]
REAS3: Modeling Radio Emission from Cosmic Ray Air Showers

The freely available Monte Carlo code REAS for modelling radio emission from cosmic ray air showers has evolved to include the full complexity of air shower physics. REAS3 improves the calculation of the emission contributions, which was not fully consistent in earlier versions of REAS, by incorporating the missing radio emission due to the variation of the number of charged particles during the air shower evolution using an "end-point formalism". With the inclusion of these emission contributions, the structure of the simulated radio pulses changes from unipolar to bipolar, and the azimuthal emission pattern becomes nearly symmetric. Remaining asymmetries can be explained by radio emission due to the variation of the net charge excess in air showers, which is automatically taken into account in the new implementation. REAS3 constitutes the first self-consistent time-domain implementation based on single particle emission taking the full complexity of air shower physics into account, and is freely available for all interested users. REAS3 has been superseded by CoREAS (ascl:1406.003).

[ascl:1506.007]
REALMAF: Magnetic power spectra from Faraday rotation maps

REALMAF is a maximum-a-posteriori code to measure magnetic power spectra from Faraday rotation data. It uses a sophisticated model for the magnetic autocorrelation in real space, thus alleviating the need for simplifying assumptions in the processing. REALMAF treats the divergence relation of the magnetic field with a multiplicative factor in Fourier space, which allows modeling the magnetic autocorrelation as a spherically symmetric function.

[ascl:1408.017]
RDGEN: Routines for data handling, display, and adjusting

RDGEN is a collection of routines for data handling, display, and adjusting, with a facility which helps to set up files for using with VPFIT (ascl:1408.015); it is included in the VPFIT distribution file. It is useful for setting region boundaries and initial guesses for VPFIT, for displaying the accumulated results, for examining by eye particular redshift systems and fits to them, testing that the error array is a true reflection of the rms scatter in the data, comparing spectra and generally examining and even modifying the data.

[ascl:1411.006]
RC3 mosaicking pipeline: Creating mosaics for the RC3 Catalogue

The RC3 mosaicking pipeline creates color composite images and scientifically-calibrated FITS mosaics in all SDSS imaging bands for all the RC3 galaxies that lie within the survey’s footprint and on photographic plates taken by the Digitized Palomar Observatory Sky Survey (DPOSS) for the B, R, IR bands. The pipeline uses SExtractor (ascl:1010.064) for extraction and STIFF (ascl:1110.006) to generating color images. The mosaicking program uses a recursive algorithm for positional update first to correct the positional inaccuracy inherent in the RC3 catalog, then conducts the mosaicking procedure using the Astropy (ascl:1304.002) wrapper to IPAC's Montage (ascl:1010.036) software. The program is generalized into a pipeline that can be easily extended to future survey data or other source catalogs; an online interface is available at

http://lcdm.astro.illinois.edu/data/rc3/search.html.

[ascl:1105.009]
Ray Tracing Codes: run_tau, run_raypath, and ray_kernel

Time-distance helioseismology aims to measure and interpret the travel times of waves propagating between two points located on the solar surface. The travel times are then inverted to infer sub-surface properties that are encoded in the measurements. The trajectory of the waves generally follows that of the infinite-frequency ray path, although they are sensitive to perturbations off of this path. Finite-frequency sensitivity kernels are thus needed to give more accurate inversion results.

Ray tracing codes calculate travel time kernels for a ray. There are three main codes which calculate the group time as a function of distance, the ray paths as well as the phase and group times along the path, and the ray kernels for the sound speed squared.

[ascl:0008.002]
RATRAN: Radiative Transfer and Molecular Excitation in One and Two Dimensions

RATRAN is a numerical method and computer code to calculate the radiative transfer and excitation of molecular lines. The approach is based on the Monte Carlo method, and incorporates elements from Accelerated Lambda Iteration. It combines the flexibility of the former with the speed and accuracy of the latter. Convergence problems known to plague Monte Carlo methods at large optical depth (>100) are avoided by separating local contributions to the radiation field from the overall transfer problem. The random nature of the Monte Carlo method serves to verify the independence of the solution to the angular, spatial, and frequency sampling of the radiation field. This allows the method to be used in a wide variety of astrophysical problems without specific adaptations. Moreover, the code can be applied to all atoms or molecules for which collisional rate coefficients are available and any axially symmetric source model. Continuum emission and absorption by dust is explicitly taken into account but scattering is neglected. We expect this program to be an important tool in analyzing data from present and future infrared and (sub-)millimeter telescopes.

[ascl:1904.014]
rate: Reliable Analytic Thermochemical Equilibrium

rate computes thermochemical-equilibrium abundances for a H-C-N-O system with known pressure, temperature, and elemental abundances. The output abundances are H2O, CH4, CO, CO2, NH3, C2H2, C2H4, HCN, and N2, H2, H, and He.

[ascl:1803.015]
RAPTOR: Imaging code for relativistic plasmas in strong gravity

Bronzwaer, Thomas; Davelaar, Jordy; Younsi, Ziri; Mościbrodzka, Monika; Falcke, Heino; Kramer, Michael; Rezzolla, Luciano

RAPTOR produces accurate images, animations, and spectra of relativistic plasmas in strong gravity by numerically integrating the equations of motion of light rays and performing time-dependent radiative transfer calculations along the rays. The code is compatible with any analytical or numerical spacetime, is hardware-agnostic and may be compiled and run on both GPUs and CPUs. RAPTOR is useful for studying accretion models of supermassive black holes, performing time-dependent radiative transfer through general relativistic magneto-hydrodynamical (GRMHD) simulations and investigating the expected observational differences between the so-called fastlight and slow-light paradigms.

[ascl:1011.007]
RAMSES: A new N-body and hydrodynamical code

A new N-body and hydrodynamical code, called RAMSES, is presented. It has been designed to study structure formation in the universe with high spatial resolution. The code is based on Adaptive Mesh Refinement (AMR) technique, with a tree based data structure allowing recursive grid refinements on a cell-by-cell basis. The N-body solver is very similar to the one developed for the ART code (Kravtsov et al. 97), with minor differences in the exact implementation. The hydrodynamical solver is based on a second-order Godunov method, a modern shock-capturing scheme known to compute accurately the thermal history of the fluid component. The accuracy of the code is carefully estimated using various test cases, from pure gas dynamical tests to cosmological ones. The specific refinement strategy used in cosmological simulations is described, and potential spurious effects associated to shock waves propagation in the resulting AMR grid are discussed and found to be negligible. Results obtained in a large N-body and hydrodynamical simulation of structure formation in a low density LCDM universe are finally reported, with 256^3 particles and 4.1 10^7 cells in the AMR grid, reaching a formal resolution of 8192^3. A convergence analysis of different quantities, such as dark matter density power spectrum, gas pressure power spectrum and individual haloes temperature profiles, shows that numerical results are converging down to the actual resolution limit of the code, and are well reproduced by recent analytical predictions in the framework of the halo model.

[ascl:1710.013]
Ramses-GPU: Second order MUSCL-Handcock finite volume fluid solver

RamsesGPU is a reimplementation of RAMSES (ascl:1011.007) which drops the adaptive mesh refinement (AMR) features to optimize 3D uniform grid algorithms for modern graphics processor units (GPU) to provide an efficient software package for astrophysics applications that do not need AMR features but do require a very large number of integration time steps. RamsesGPU provides an very efficient C++/CUDA/MPI software implementation of a second order MUSCL-Handcock finite volume fluid solver for compressible hydrodynamics as a magnetohydrodynamics solver based on the constraint transport technique. Other useful modules includes static gravity, dissipative terms (viscosity, resistivity), and forcing source term for turbulence studies, and special care was taken to enhance parallel input/output performance by using state-of-the-art libraries such as HDF5 and parallel-netcdf.

[ascl:1411.010]
Raga: Monte Carlo simulations of gravitational dynamics of non-spherical stellar systems

Raga (Relaxation in Any Geometry) is a Monte Carlo simulation method for gravitational dynamics of non-spherical stellar systems. It is based on the SMILE software (ascl:1308.001) for orbit analysis. It can simulate stellar systems with a much smaller number of particles N than the number of stars in the actual system, represent an arbitrary non-spherical potential with a basis-set or spline spherical-harmonic expansion with the coefficients of expansion computed from particle trajectories, and compute particle trajectories independently and in parallel using a high-accuracy adaptive-timestep integrator. Raga can also model two-body relaxation by local (position-dependent) velocity diffusion coefficients (as in Spitzer's Monte Carlo formulation) and adjust the magnitude of relaxation to the actual number of stars in the target system, and model the effect of a central massive black hole.

[ascl:1902.008]
Radynversion: Solar atmospheric properties during a solar flare

Radynversion infers solar atmospheric properties during a solar flare. The code is based on an Invertible Neural Network (INN) that is trained to learn an approximate bijective mapping between the atmospheric properties of electron density, temperature, and bulk velocity (all as a function of altitude), and the observed Hα and Ca II λ8542 line profiles. As information is lost in the forward process of radiation transfer, this information is injected back into the model during the inverse process by means of a latent space; the training allows this latent space to be filled using an n-dimensional unit Gaussian distribution, where n is the dimensionality of the latent space. The code is based on a model trained by simulations made by RADYN, a 1D non-equilibrium radiation hydrodynamic model with good optically thick radiation treatment that does not consider magnetic effects.

[ascl:1801.012]
RadVel: General toolkit for modeling Radial Velocities

RadVel models Keplerian orbits in radial velocity (RV) time series. The code is written in Python with a fast Kepler's equation solver written in C. It provides a framework for fitting RVs using maximum a posteriori optimization and computing robust confidence intervals by sampling the posterior probability density via Markov Chain Monte Carlo (MCMC). RadVel can perform Bayesian model comparison and produces publication quality plots and LaTeX tables.

[ascl:9910.009]
RADPACK: A RADical compression analysis PACKage for fitting to the CMB

The RADPACK package, written in IDL, contains both data and software. The data are the constraints on the cosmic microwave background (CMB) angular power spectrum from all published data as of 9/99. A unique aspect of this compilation is that the non-Gaussianity of the uncertainties has been characterized. The most important program in the package, written in the IDL language, is called chisq.pro and calculates $chi^2$, for an input power spectrum, according to the offset log-normal form of Bond, Jaffe and Knox (astro-ph/9808264). chisq.pro also outputs files that are useful for examining the residuals (the difference between the predictions of the model and the data). There is an sm macro for plotting up the residuals, and a histogram of the residuals. The histogram is actually for the 'whitenend' residuals ---a linear combination of the residuals which leaves them uncorrelated and with unit variance. The expectation is that the whitened residuals will be distributed as a Gaussian with unit variance.

[ascl:1811.015]
radon: Streak detection using the Fast Radon Transform

radon performs a Fast Radon Transform (FRT) on image data for streak detection. The software finds short streaks and multiple streaks, convolves the images with a given PSF, and tracks the best S/N results and find a automatic threshold. It also calculates the streak parameters in the input image and the streak parameters in the input image. radon has a simulator that can make multiple streaks of different intensities and coordinates, and can simulate random streaks with parameters chosen uniformly in a user-defined range.

[ascl:1108.016]
RADMC: A 2-D Continuum Radiative Transfer Tool

RADMC is a 2-D Monte-Carlo code for dust continuum radiative transfer circumstellar disks and envelopes. It is based on the method of Bjorkman & Wood (ApJ 2001, 554, 615), but with several modifications to produce smoother results with fewer photon packages.

[ascl:1202.015]
RADMC-3D: A multi-purpose radiative transfer tool

Dullemond, C. P.; Juhasz, A.; Pohl, A.; Sereshti, F.; Shetty, R.; Peters, T.; Commercon, B.; Flock, M.

RADMC-3D is a software package for astrophysical radiative transfer calculations in arbitrary 1-D, 2-D or 3-D geometries. It is mainly written for continuum radiative transfer in dusty media, but also includes modules for gas line transfer and gas continuum transfer. RADMC-3D is a new incarnation of the older software package RADMC (ascl:1108.016).

[ascl:1308.012]
RADLite: Raytracer for infrared line spectra

RADLite is a raytracer that is optimized for producing infrared line spectra and images from axisymmetric density structures, originally developed to function on top of the dust radiative transfer code RADMC. RADLite can consistently deal with a wide range of velocity gradients, such as those typical for the inner regions of protoplanetary disks. The code is intended as a back-end for chemical and excitation codes, and can rapidly produce spectra of thousands of lines for grids of models for comparison with observations. It includes functionality for simulating telescopic images for optical/IR/midIR/farIR telescopes. It takes advantage of multi-threaded CPUs and includes an escape-probability non-LTE module.

[ascl:1108.014]
RADICAL: Multi-purpose 2-D Radiative Transfer Code

RADICAL is a multi-purpose 2-D radiative transfer code for axi-symmetric circumstellar (or circum-black-hole) envelopes /disks / tori etc. It has been extensively tested and found reliable and accurate. The code has recently been supplemented with a Variable Eddington Tensor module which enables it to solve dust continuum radiative transfer problems from very low up to extremely high optical depths with only a few (about 7) iterations at most.

[ascl:1806.017]
RadFil: Radial density profile builder for interstellar filaments

RadFil is a radial density profile building and fitting tool for interstellar filaments. The software uses an image array and (in most cases) a boolean mask array that delineates the boundary of the filament to build and fit a radial density profile for the filaments.

[ascl:1010.075]
Radex: Fast Non-LTE Analysis of Interstellar Line Spectra

The large quantity and high quality of modern radio and infrared line observations require efficient modeling techniques to infer physical and chemical parameters such as temperature, density, and molecular abundances. Radex calculates the intensities of atomic and molecular lines produced in a uniform medium, based on statistical equilibrium calculations involving collisional and radiative processes and including radiation from background sources. Optical depth effects are treated with an escape probability method. The program makes use of molecular data files maintained in the Leiden Atomic and Molecular Database (LAMDA), which will continue to be improved and expanded. The performance of the program is compared with more approximate and with more sophisticated methods. An Appendix provides diagnostic plots to estimate physical parameters from line intensity ratios of commonly observed molecules. This program should form an important tool in analyzing observations from current and future radio and infrared telescopes.

[ascl:1711.015]
rac-2d: Thermo-chemical for modeling water vapor formation in protoplanetary disks

rec-2d models the distribution of water vapor in protoplanetary disks. Given a distribution of gas and dust, rac-2d first solves the dust temperature distribution with a Monte Carlo method and then solves the gas temperature distribution and chemical composition. Although the geometry is symmetric with respect to rotation around the central axis and reflection about the midplane, the photon propagation is done in full three dimensions. After establishing the dust temperature distribution, the disk chemistry is evolved for 1 Myr; the heating and cooling processes are coupled with chemistry, allowing the gas temperature to be evolved in tandem with chemistry based on the heating and cooling rates.

[ascl:1502.013]
Rabacus: Analytic Cosmological Radiative Transfer Calculations

Rabacus performs analytic radiative transfer calculations in simple geometries relevant to cosmology and astrophysics; it also contains tools to calculate cosmological quantities such as the power spectrum and mass function. With core routines written in Fortran 90 and then wrapped in Python, the execution speed is thousands of times faster than equivalent routines written in pure Python.

[ascl:1106.005]
R3D: Reduction Package for Integral Field Spectroscopy

R3D was developed to reduce fiber-based integral field spectroscopy (IFS) data. The package comprises a set of command-line routines adapted for each of these steps, suitable for creating pipelines. The routines have been tested against simulations, and against real data from various integral field spectrographs (PMAS, PPAK, GMOS, VIMOS and INTEGRAL). Particular attention is paid to the treatment of cross-talk.

R3D unifies the reduction techniques for the different IFS instruments to a single one, in order to allow the general public to reduce different instruments data in an homogeneus, consistent and simple way. Although still in its prototyping phase, it has been proved to be useful to reduce PMAS (both in the Larr and the PPAK modes), VIMOS and INTEGRAL data. The current version has been coded in Perl, using PDL, in order to speed-up the algorithm testing phase. Most of the time critical algorithms have been translated to C[float=][/float], and it is our intention to translate all of them. However, even in this phase R3D is fast enough to produce valuable science frames in reasonable time.

[ascl:1104.009]
r-Java: An r-process Code and Graphical User Interface for Heavy-Element Nucleosynthesis

r-Java performs r-process nucleosynthesis calculations. It has a simple graphical user interface and is carries out nuclear statistical equilibrium (NSE) as well as static and dynamic r-process calculations for a wide range of input parameters. r-Java generates an abundance pattern based on a general entropy expression that can be applied to degenerate as well as non-degenerate matter, which allows tracking of the rapid density and temperature evolution of the ejecta during the initial stages of ejecta expansion.

[ascl:1210.028]
QYMSYM: A GPU-accelerated hybrid symplectic integrator

QYMSYM is a GPU accelerated 2nd order hybrid symplectic integrator that identifies close approaches between particles and switches from symplectic to Hermite algorithms for particles that require higher resolution integrations. This is a parallel code running with CUDA on a video card that puts the many processors on board to work while taking advantage of fast shared memory.

[ascl:1811.006]
QuickSip: Project survey image properties onto the sky into Healpix maps

QuickSip quickly projects Survey Image Properties (e.g. seeing, sky noise, airmass) into Healpix sky maps with flexible weighting schemes. It was initially designed to produce observing condition "systematics" maps for the Dark Energy Survey (DES), but will work with any multi-epoch survey and images with valid WCS. QuickSip can reproduce the Mangle (ascl:1202.005) magnitude limit maps at sub-percent accuracy but doesn't support additional masks (stars, trails, etc), in which case Mangle should be used. Thus, QuickSip can be seen as a simplified Mangle to project image properties into Healpix maps in a fast and more flexible manner.

[ascl:1402.024]
QuickReduce: Data reduction pipeline for the WIYN One Degree Imager

QuickReduce quickly reduces data for ODI and is optimized for a first data inspection during acquisition at the the telescope. When installed on the ODI observer's interface, QuickReduce, coded in Python, performs all basic reduction steps as well as more advanced corrections for pupil-ghost removal, fringe correction and masking of persistent pixels and is capable enough for science-quality data reductions. It can also add an accurate astrometric WCS solution based on the 2MASS reference system as well as photometric zeropoint calibration for frames covered by the SDSS foot-print. The pipeline makes use of multiple CPU-cores wherever possible, resulting in an execution time of only a few seconds per frame, thus offering the ODI observer a convenient way to closely monitor data quality.

[ascl:1402.012]
QUICKCV: Cosmic variance calculator

QUICKCV is an IDL sample variance/cosmic variance calculator for some geometry for galaxies in given stellar mass bins as a function of mean redshift and redshift bin size.

[ascl:1704.006]
Quickclump: Identify clumps within a 3D FITS datacube

Quickclump finds clumps in a 3D FITS datacube. It is a fast, accurate, and automated tool written in Python. Though Quickclump is primarily intended for decomposing observations of interstellar clouds into individual clumps, it can also be used for finding clumps in any 3D rectangular data.

[ascl:1703.011]
QtClassify: IFS data emission line candidates classifier

QtClassify is a GUI that helps classify emission lines found in integral field spectroscopic data. Input needed is a datacube as well as a catalog with emission lines and a signal-to-noise cube, such at that created by LSDCat (ascl:1612.002). The main idea is to take each detected line and guess what line it could be (and thus the redshift of the object). You would expect to see other lines that might not have been detected but are visible in the cube if you know where to look, which is why parts of the spectrum are shown where other lines are expected. In addition, monochromatic layers of the datacube are displayed, making it easy to spot additional emission lines.

[ascl:1612.011]
QSFit: Quasar Spectral FITting

QSFit performs automatic analysis of Active Galactic Nuclei (AGN) optical spectra. It provides estimates of: AGN continuum luminosities and slopes at several restframe wavelengths; luminosities, widths and velocity offsets of 20 emission lines; luminosities of iron blended lines at optical and UV wavelengths; host galaxy luminosities. The whole fitting process is customizable for specific needs, and can be extended to analyze spectra from other data sources. The ultimate purpose of QSFit is to allow astronomers to run standardized recipes to analyze the AGN data, in a simple, replicable and shareable way.

[ascl:1809.011]
qp: Quantile parametrization for probability distribution functions

qp manipulates parametrizations of 1-dimensional probability distribution functions, as suitable for photo-z PDF compression. The code helps determine a parameterization for storing a catalog of photo-z PDFs that balances the available storage resources against the accuracy of the photo-z PDFs and science products reconstructed from the stored parameters.

[ascl:1304.016]
Qhull: Quickhull algorithm for computing the convex hull

Qhull computes the convex hull, Delaunay triangulation, Voronoi diagram, halfspace intersection about a point, furthest-site Delaunay triangulation, and furthest-site Voronoi diagram. The source code runs in 2-d, 3-d, 4-d, and higher dimensions. Qhull implements the Quickhull algorithm for computing the convex hull. It handles roundoff errors from floating point arithmetic. It computes volumes, surface areas, and approximations to the convex hull.

[ascl:1210.019]
QFitsView: FITS file viewer

QFitsView is a FITS file viewer that can display one, two, and three-dimensional FITS files. It has three modes of operation, depending of what kind of data is being displayed. One-dimensional data are shown in an x-y plot. Two-dimensional images are shown in the main window. Three-dimensional data cubes can be displayed in a variety of ways, with the third dimension shown as a x-y plot at the bottom of the image display. QFitsView was written in C++ and uses the Qt widget library, which makes it available for all major platforms: Windows, MAC OS X, and many Unix variants.

[ascl:1806.006]
QE: Quantum opEn-Source Package for Research in Electronic Structure, Simulation, and Optimization

Giannozzi, P.; Andreussi, O.; Baroni, S.; Bonini, Nicola; Brumme, T.; Bunau, O.; Buongiorno Nardelli, M.; Calandra, M.; Car, R.; Cavazzoni, C.; Ceresoli, D.; Chiarotti, Guido L.; Cococcioni, M.; Colonna, N.; Carnimeo, I.; Dabo, Ismaila; Dal Corso, A.; de Gironcoli, S.; Delugas, P.; DiStasio, R. A., Jr.; Fabris, Stefano; Ferretti, A.; Floris, A.; Fratesi, G.; Fugallo, G.; Gebauer, R.; Gerstmann, U.; Giustino, F.; Gorni, T.; Gougoussis, Christos; Jia, J.; Kawamura, M.; Ko, H.-Y.; Kokalj, A.; Küçükbenli, E.; Lazzeri, M.; Marsili, M.; Martin-Samos, Layla; Marzari, N.; Mauri, F.; Mazzarello, Riccardo; Nguyen, N. L.; Nguyen, H.-V.; Otero-de-la-Roza, A.; Paolini, Stefano; Pasquarello, Alfredo; Paulatto, L.; Poncé, S.; Rocca, D.; Sabatini, R.; Santra, B.; Sbraccia, Scandolo, Sandro; Carlo; Schlipf, M.; Sclauzero, Gabriele; Seitsonen, A. P.; Smogunov, A.; Timrov, I.; Thonhauser, T.; Umari, P.; Vast, N.; Wentzcovitch, Renata M.; Wu, X.

Quantum ESPRESSO (opEn-Source Package for Research in Electronic Structure, Simulation, and Optimization) is an integrated suite of codes for electronic-structure calculations and materials modeling at the nanoscale. It is based on density-functional theory, plane waves, and pseudopotentials. QE performs ground-state calculations such as self-consistent total energies, forces, stresses and Kohn-Sham orbitals, Car-Parrinello and Born-Oppenheimer molecular dynamics, and quantum transport such as ballistic transport, coherent transport from maximally localized Wannier functions, and Kubo-Greenwood electrical conductivity. It can also determine spectroscopic properties and examine time-dependent density functional perturbations and electronic excitations, and has a wide range of other functions.

[ascl:1601.015]
QDPHOT: Quick & Dirty PHOTometry

QDPHOT is a fast CCD stellar photometry task which quickly produces CCD stellar photometry from two CCD images of a star field. It was designed to be a data mining tool for finding high-quality stellar observations in the data archives of the National Virtual Observatory. QDPHOT typically takes just a few seconds to analyze two Hubble Space Telescope WFPC2 observations of Local Group star clusters. It is also suitable for real-time data-quality analysis of CCD observations; on-the-fly instrumental color-magnitude diagrams can be produced at the telescope console during the few seconds between CCD readouts.

[ascl:1712.014]
QATS: Quasiperiodic Automated Transit Search

QATS detects transiting extrasolar planets in time-series photometry. It relaxes the usual assumption of strictly periodic transits by permitting a variable, but bounded, interval between successive transits.

[ascl:1905.008]
Q3C: A PostgreSQL package for spatial queries and cross-matches of large astronomical catalogs

Q3C (Quad Tree Cube) enables fast cone, ellipse and polygonal searches and cross-matches between large astronomical catalogs inside a PostgreSQL database. The package supports searches even if objects have proper motions.

[ascl:1806.003]
pyZELDA: Python code for Zernike wavefront sensors

pyZELDA analyzes data from Zernike wavefront sensors dedicated to high-contrast imaging applications. This modular software was originally designed to analyze data from the ZELDA wavefront sensor prototype installed in VLT/SPHERE; simple configuration files allow it to be extended to support several other instruments and testbeds. pyZELDA also includes simple simulation tools to measure the theoretical sensitivity of a sensor and to compare it to other sensors.

[ascl:1608.002]
pyXSIM: Synthetic X-ray observations generator

pyXSIM simulates X-ray observations from astrophysical sources. X-rays probe the high-energy universe, from hot galaxy clusters to compact objects such as neutron stars and black holes and many interesting sources in between. pyXSIM generates synthetic X-ray observations of these sources from a wide variety of models, whether from grid-based simulation codes such as FLASH (ascl:1010.082), Enzo (ascl:1010.072), and Athena (ascl:1010.014), to particle-based codes such as Gadget (ascl:0003.001) and AREPO, and even from datasets that have been created “by hand”, such as from NumPy arrays. pyXSIM can also manipulate the synthetic observations it produces in various ways and export the simulated X-ray events to other software packages to simulate the end products of specific X-ray observatories. pyXSIM is an implementation of the PHOX (ascl:1112.004) algorithm and was initially the photon_simulator analysis module in yt (ascl:1011.022); it is dependent on yt.

[ascl:1402.034]
PyWiFeS: Wide Field Spectrograph data reduction pipeline

PyWiFeS is a Python-based data reduction pipeline for the Wide Field Spectrograph (WiFeS). Its core data processing routines are built on standard scientific Python packages commonly used in astronomical applications. It includes an implementation of a global optical model of the spectrograph which provides wavelengths solutions accurate to ˜0.05 Å (RMS) across the entire detector. Through scripting, PyWiFeS can enable batch processing of large quantities of data.

[ascl:1402.004]
PyVO: Python access to the Virtual Observatory

PyVO provides access to remote data and services of the Virtual observatory (VO) using Python. It allows archive searches for data of a particular type or related to a particular topic and query submissions to obtain data to a particular archive to download selected data products. PyVO supports querying the VAO registry; simple data access services (DAL) to access images (SIA), source catalog records (Cone Search), spectra (SSA), and spectral line emission/absorption data (SLAP); and object name resolution (for converting names of objects in the sky into positions). PyVO requires both AstroPy and NumPy.

[ascl:1907.003]
pyuvdata: Pythonic interface to interferometric data sets

pyuvdata defines a pythonic interface to interferometric data sets; it supports the development of and interchange of data between calibration and foreground subtraction pipelines. It can read and write MIRIAD (ascl:1106.007), uvfits, and uvh5 files and reads CASA (ascl:1107.013) measurement sets and FHD (Fast Holographic Deconvolution) visibility save files. Particular focus has been paid to supporting drift and phased array modes.

[ascl:1810.009]
PyUltraLight: Pseudo-spectral Python code to compute ultralight dark matter dynamics

PyUltraLight computes non-relativistic ultralight dark matter dynamics in a static spacetime background. It uses pseudo-spectral methods to compute the evolution of a complex scalar field governed by the Schrödinger-Poisson system of coupled differential equations. Computations are performed on a fixed-grid with periodic boundary conditions, allowing for a decomposition of the field in momentum space by way of the discrete Fourier transform. The field is then evolved through a symmetrized split-step Fourier algorithm, in which nonlinear operators are applied in real space, while spatial derivatives are computed in Fourier space. Fourier transforms within PyUltraLight are handled using the pyFFTW pythonic wrapper around FFTW (ascl:1201.015).

[ascl:1710.010]
PyTransport: Calculate inflationary correlation functions

PyTransport calculates the 2-point and 3-point function of inflationary perturbations produced during multi-field inflation. The core of PyTransport is C++ code which is automatically edited and compiled into a Python module once an inflationary potential is specified. This module can then be called to solve the background inflationary cosmology as well as the evolution of correlations of inflationary perturbations. PyTransport includes two additional modules written in Python, one to perform the editing and compilation, and one containing a suite of functions for common tasks such as looping over the core module to construct spectra and bispectra.

[ascl:1505.024]
PyTransit: Transit light curve modeling

PyTransit implements optimized versions of the Giménez and Mandel & Agol transit models for exoplanet transit light-curves. The two models are implemented natively in Fortran with OpenMP parallelization, and are accessed by an object-oriented python interface. PyTransit facilitates the analysis of photometric time series of exoplanet transits consisting of hundreds of thousands of data points, and of multipassband transit light curves from spectrophotometric observations. It offers efficient model evaluation for multicolour observations and transmission spectroscopy, built-in supersampling to account for extended exposure times, and routines to calculate the projected planet-to-star distance for circular and eccentric orbits, transit durations, and more.

[ascl:1501.010]
PythonPhot: Simple DAOPHOT-type photometry in Python

PythonPhot is a simple Python translation of DAOPHOT-type (ascl:1104.011) photometry procedures from the IDL AstroLib (Landsman 1993), including aperture and PSF-fitting algorithms, with a few modest additions to increase functionality and ease of use. These codes allow fast, easy, and reliable photometric measurements and are currently used in the Pan-STARRS supernova pipeline and the HST CLASH/CANDELS supernova analysis.

[ascl:1501.003]
python-qucs: Python package for automating QUCS simulations

Characterization of the frequency response of coherent radiometric receivers is a key element in estimating the flux of astrophysical emissions, since the measured signal depends on the convolution of the source spectral emission with the instrument band shape. Python-qucs automates the process of preparing input data, running simulations and exporting results of QUCS (Quasi Universal Circuit Simulator) simulations.

[ascl:1612.001]
Python-CPL: Python interface for the ESO Common Pipeline Library

Python-CPL is a framework to configure and execute pipeline recipes written with the Common Pipeline Library (CPL) (ascl:1402.010) with Python2 or Python3. The input, calibration and output data can be specified as FITS files or as astropy.io.fits objects in memory. The package is used to implement the MUSE pipeline in the AstroWISE data management system.

[ascl:1303.023]
pysynphot: Synthetic photometry software package

pysynphot is a synthetic photometry software package suitable for either library or interactive use. Intended as a modern-language successor to the IRAF/STSDAS synphot package, it provides improved algorithms that address known shortcomings in synphot, and its object-oriented design is more easily extensible than synphot's task-oriented approach. It runs under PyRAF (ascl:1207.011), and a backwards compatibility mode is provided that recognizes all spectral and throughput tables, obsmodes, and spectral expressions used by synphot, to facilitate the transition for legacy code.

[ascl:1109.001]
PySpecKit: Python Spectroscopic Toolkit

PySpecKit is a Python spectroscopic analysis and reduction toolkit meant to be generally applicable to optical, infrared, and radio spectra. It is capable of reading FITS-standard and many non-standard file types including CLASS spectra. It contains procedures for line fitting including gaussian and voigt profile fitters, and baseline-subtraction routines. It is capable of more advanced line fitting using arbitrary model grids. Fitting can be done both in batch mode and interactively. PySpecKit also produces publication-quality plots with TeX axis labels and annotations. It is designed to be extensible, allowing user-written reader, writer, and fitting routines to be "plugged in." It is actively under development and currently in the 'alpha' phase, with plans for a beta release.

[ascl:1411.002]
pysovo: A library for implementing alerts triggered by VOEvents

pysovo contains basic tools to work with VOEvents. Though written for specific needs, others interested in VOEvents may find it useful to examine.

[ascl:1503.008]
pYSOVAR: Lightcurves analysis

The pYSOVAR code calculates properties for a stack of lightcurves, including simple descriptive statistics (mean, max, min, ...), timing (e.g. Lomb-Scargle periodograms), variability indixes (e.g. Stetson), and color properties (e.g. slope in the color-magnitude diagram). The code is written in python and is closely integrated with astropy tables. Initially, pYSOVAR was written specifically for the analysis of two clusters in the YSOVAR project, using the (not publicly released) YSOVAR database as an input. Additional functionality has been added and the code has become more general; it is now useful for other clusters in the YSOVAR dataset or for other projects that have similar data (lightcurves in one or more bands with a few hundred points for a few thousand objects), though may not work out-of-the-box for different datasets.

[ascl:1704.007]
PySM: Python Sky Model

PySM generates full-sky simulations of Galactic foregrounds in intensity and polarization relevant for CMB experiments. The components simulated are thermal dust, synchrotron, AME, free-free, and CMB at a given Nside, with an option to integrate over a top hat bandpass, to add white instrument noise, and to smooth with a given beam. PySM is based on the large-scale Galactic part of Planck Sky Model code and uses some of its inputs.

[ascl:1805.026]
PySE: Python Source Extractor for radio astronomical images

Spreeuw, Hanno; Swinbank, John; Molenaar, Gijs; Staley, Tim; Rol, Evert; Sanders, John; Scheers, Bart; Kuiack, Mark

PySE finds and measures sources in radio telescope images. It is run with several options, such as the detection threshold (a multiple of the local noise), grid size, and the forced clean beam fit, followed by a list of input image files in standard FITS or CASA format. From these, PySe provides a list of found sources; information such as the calculated background image, source list in different formats (e.g. text, region files importable in DS9), and other data may be saved. PySe can be integrated into a pipeline; it was originally written as part of the LOFAR Transient Detection Pipeline (TraP, ascl:1412.011).

[ascl:1207.010]
PySALT: SALT science pipeline

Crawford, S. M.; Still, M.; Schellart, P.; Balona, L.; Buckley, D. A. H.; Gulbis, A. A. S.; Kniazev, A.; Kotze, M.; Loaring, N.; Nordsieck, K. H.; Pickering, T. E.; Potter, S.; Romero Colmenero, E.; Vaisanen, P.; Wiliams, T.; Zietsman, E.

The PySALT user package contains the primary reduction and analysis software tools for the SALT telescope. Currently, these tools include basic data reductions for RSS and SALTICAM in both imaging, spectroscopic, and slot modes. Basic analysis software for slot mode data is also provided. These tools are primarily written in python/PyRAF with some additional IRAF code.

[ascl:1904.026]
pyRSD: Accurate predictions for the clustering of galaxies in redshift-space in Python

pyRSD computes the theoretical predictions of the redshift-space power spectrum of galaxies. It also includes functionality for fitting data measurements and finding the optimal model parameters, using both MCMC and nonlinear optimization techniques.

[ascl:1507.018]
pyro: Python-based tutorial for computational methods for hydrodynamics

pyro is a simple python-based tutorial on computational methods for hydrodynamics. It includes 2-d solvers for advection, compressible, incompressible, and low Mach number hydrodynamics, diffusion, and multigrid. It is written with ease of understanding in mind. An extensive set of notes that is part of the Open Astrophysics Bookshelf project provides details of the algorithms.

[ascl:1207.011]
PyRAF: Python alternative for IRAF

PyRAF is a command language for running IRAF tasks that is based on the Python scripting language. It gives users the ability to run IRAF tasks in an environment that has all the power and flexibility of Python. PyRAF can be installed along with an existing IRAF installation; users can then choose to run either PyRAF or the IRAF CL.

[ascl:1602.002]
pyraf-dbsp: Reduction pipeline for the Palomar Double Beam Spectrograph

pyraf-dbsp is a PyRAF-based (ascl:1207.011) reduction pipeline for optical spectra taken with the Palomar 200-inch Double Beam Spectrograph. The pipeline provides a simplified interface for basic reduction of single-object spectra with minimal overhead. It is suitable for quicklook classification of transients as well as moderate-precision (few km/s) radial velocity work.

[ascl:1807.006]
pyqz: Emission line code

pyqz computes the values of log(Q) [the ionization parameter] and 12+log(O/H) [the oxygen abundance, either total or in the gas phase] for a given set of strong emission lines fluxes from HII regions. The log(Q) and 12+log(O/H) values are interpolated from a finite set of diagnostic line ratio grids computed with the MAPPINGS V code (ascl:1807.005). The grids used by pyqz are chosen to be flat, without wraps, to decouple the influence of log(Q) and 12+log(O/H) on the emission line ratios.

[ascl:1809.008]
PyQSOFit: Python code to fit the spectrum of quasars

The Python QSO fitting code (PyQSOFit) measures spectral properties of quasars. Based on Shen's IDL version, this code decomposes different components in the quasar spectrum, e.g., host galaxy, power-law continuum, Fe II component, and emission lines. In addition, it can run Monto Carlo iterations using flux randomization to estimate the uncertainties.

[ascl:1706.011]
PyPulse: PSRFITS handler

PyPulse handles PSRFITS files and performs subsequent analyses on pulse profiles.

[ascl:1612.005]
PyProfit: Wrapper for libprofit

pyprofit is a python wrapper for libprofit (ascl:1612.003).

[ascl:1609.022]
PyPHER: Python-based PSF Homogenization kERnels

Boucaud, Alexandre; Bocchio, Marco; Abergel, Alain; Orieux, François; Dole, Hervé; Amine Hadj-Youcef, Mohamed

PyPHER (Python-based PSF Homogenization kERnels) computes an homogenization kernel between two PSFs; the code is well-suited for PSF matching applications in both an astronomical or microscopy context. It can warp (rotation + resampling) the PSF images (if necessary), filter images in Fourier space using a regularized Wiener filter, and produce a homogenization kernel. PyPHER requires the pixel scale information to be present in the FITS files, which can if necessary be added by using the provided ADDPIXSCL method.

[ascl:1905.027]
PyPDR: Python Photo Dissociation Regions

PyPDR calculates the chemistry, thermal balance and molecular excitation of a slab of gas under FUV irradiation in a self-consistent way. The effect of FUV irradiation on the chemistry is that molecules get photodissociated and the gas is heated up to several 1000 K, mostly by the photoelectric effect on small dust grains or UV pumping of H2 followed by collision de-excitation. The gas is cooled by molecular and atomic lines, thus indirectly the chemical composition also affects the thermal structure through the abundance of molecules and atoms. To find a self-consistent solution between heating and cooling, the code iteratively calculates the chemistry, thermal-balance and molecular/atomic excitation.

[ascl:1802.012]
PyOSE: Orbital sampling effect (OSE) simulator

PyOSE is a fully numerical orbital sampling effect (OSE) simulator that can model arbitrary inclinations of the transiting moon orbit. It can be used to search for exomoons in long-term stellar light curves such as those by Kepler and the upcoming PLATO mission.

[ascl:1612.008]
PyORBIT: Exoplanet orbital parameters and stellar activity

PyORBIT handles several kinds of datasets, such as radial velocity (RV), activity indexes, and photometry, to simultaneously characterize the orbital parameters of exoplanets and the noise induced by the activity of the host star. RV computation is performed using either non-interacting Kepler orbits or n-body integration. Stellar activity can be modeled either with sinusoids at the rotational period and its harmonics or Gaussian process. In addition, the code can model offsets and systematics in measurements from several instruments. The PyORBIT code is modular; new methods for stellar activity modeling or parameter estimation can easily be incorporated into the code.

[ascl:1501.001]
PynPoint: Exoplanet image data analysis

PynPoint uses principal component analysis to detect and estimate the flux of exoplanets in two-dimensional imaging data. It processes many, typically several thousands, of frames to remove the light from the star so as to reveal the companion planet.

The code has been significantly rewritten and expanded; please see ascl:1812.010.

[ascl:1812.010]
PynPoint 0.6.0: Pipeline for processing and analysis of high-contrast imaging data

PynPoint processes and analyzes high-contrast imaging data of exoplanets and circumstellar disks. The generic, end-to-end pipeline's modular architecture separates the core functionalities and the pipeline modules. These modules have specific tasks such as background subtraction, frame selection, centering, PSF subtraction with principal component analysis, estimation of detection limits, and photometric and astrometric analysis. All modules store their results in a central database. Management of the available hardware by the backend of the pipeline is in particular an advantage for data sets containing thousands of images, as is common in the mid-infrared wavelength regime. This version of PynPoint is a significant rewrite of the earlier PynPoint package (ascl:1501.001).

[ascl:1304.021]
PyNeb: Analysis of emission lines

PyNeb (previously PyNebular) is an update and expansion of the IRAF package NEBULAR; rewritten in Python, it is designed to be more user-friendly and powerful, increasing the speed, easiness of use, and graphic visualization of emission lines analysis. In PyNeb, the atom is represented as an n-level atom. For given density and temperature, PyNeb solves the equilibrium equations and determines the level populations. PyNeb can compute physical conditions from suitable diagnostic line ratios and level populations, critical densities and line emissivities, and can compute and display emissivity grids as a function of Te and Ne. It can also deredden line intensities, read and manage observational data, and plot and compare atomic data from different publications, and compute ionic abundances from line intensities and physical conditions and elemental abundances from ionic abundances and icfs.

[ascl:1305.002]
pynbody: N-Body/SPH analysis for python

Pynbody is a lightweight, portable, format-transparent analysis package for astrophysical N-body and smooth particle hydrodynamic simulations supporting PKDGRAV/Gasoline, Gadget, N-Chilada, and RAMSES AMR outputs. Written in python, the core tools are accompanied by a library of publication-level analysis routines.

[ascl:1703.009]
PyMVPA: MultiVariate Pattern Analysis in Python

PyMVPA eases statistical learning analyses of large datasets. It offers an extensible framework with a high-level interface to a broad range of algorithms for classification, regression, feature selection, data import and export. It is designed to integrate well with related software packages, such as scikit-learn, shogun, and MDP.

[ascl:1806.028]
PyMUSE: VLT/MUSE data analyzer

PyMUSE analyzes VLT/MUSE datacubes. The package is optimized to extract 1-D spectra of arbitrary spatial regions within the cube and also for producing images using photometric filters and customized masks. It is intended to provide the user the tools required for a complete analysis of a MUSE data set.

[ascl:1606.005]
PyMultiNest: Python interface for MultiNest

PyMultiNest provides programmatic access to MultiNest (ascl:1109.006) and PyCuba, integration existing Python code (numpy, scipy), and enables writing Prior & LogLikelihood functions in Python. PyMultiNest can plot and visualize MultiNest's progress and allows easy plotting, visualization and summarization of MultiNest results. The plotting can be run on existing MultiNest output, and when not using PyMultiNest for running MultiNest.

[ascl:1310.002]
PyMSES: Python modules for RAMSES

PyMSES provides a python solution for getting data out of RAMSES (ascl:1011.007) astrophysical fluid dynamics simulations. It permits transparent manipulation of large simulations and interfaces with common Python libraries and existing code, and can serve as a post-processing toolbox for data analysis. It also does three-dimensional volume rendering with a specific algorithm optimized to work on RAMSES distributed data (Guillet et al. 2011 and Jones et a. 2011).

[ascl:1906.009]
PyMORESANE: Python MOdel REconstruction by Synthesis-ANalysis Estimators

PyMORESANE is a Python and pyCUDA-accelerated implementation of the MORESANE deconvolution algorithm, a sparse deconvolution algorithm for radio interferometric imaging. It can restore diffuse astronomical sources which are faint in brightness, complex in morphology and possibly buried in the dirty beam’s side lobes of bright radio sources in the field.

[ascl:1109.010]
PyModelFit: Model-fitting Framework and GUI Tool

PyModelFit provides a pythonic, object-oriented framework that simplifies the task of designing numerical models to fit data. This is a very broad task, and hence the current functionality of PyModelFit focuses on the simpler tasks of 1D curve-fitting, including a GUI interface to simplify interactive work (using Enthought Traits). For more complicated modeling, PyModelFit also provides a wide range of classes and a framework to support more general model/data types (2D to Scalar, 3D to Scalar, 3D to 3D, and so on).

[ascl:1707.005]
PyMOC: Multi-Order Coverage map module for Python

PyMOC manipulates Multi-Order Coverage (MOC) maps. It supports reading and writing the three encodings mentioned in the IVOA MOC recommendation: FITS, JSON and ASCII.

[ascl:1808.008]
PyMieDap: Python Mie Doubling Adding Program

PyMieDAP (Python Mie Doubling Adding Program) makes light scattering computations with Mie scattering and radiative transfer computations with full orders of scattering and taking into account the polarization of the light scattered. Full planet modeling at any phase angle is possible. With the included subpackage exopy, it is also possible to simulate systems with a star, a planet and a possible moon.

[ascl:1401.003]
PyMidas: Interface from Python to Midas

PyMidas is an interface between Python and MIDAS, the major ESO legacy general purpose data processing system. PyMidas allows a user to exploit both the rich legacy of MIDAS software and the power of Python scripting in a unified interactive environment. PyMidas also allows the usage of other Python-based astronomical analysis systems such as PyRAF.

[ascl:1411.011]
PyMGC3: Finding stellar streams in the Galactic Halo using a family of Great Circle Cell counts methods

PyMGC3 is a Python toolkit to apply the Modified Great Circle Cell Counts (mGC3) method to search for tidal streams in the Galactic Halo. The code computes pole count maps using the full mGC3/nGC3/GC3 family of methods. The original GC3 method (Johnston *et al.*, 1996) uses positional information to search for 'great-circle-cell structures'; mGC3 makes use of full 6D data and nGC3 uses positional and proper motion data.

[ascl:1902.003]
PyMF: Matched filtering techniques for astronomical images

PyMF performs spatial filtering (matched filter, matched multifilter, constrained matched filter and constrained matched mutifilter) image processing that provides optimal reduction of the contamination introduced by sources that can be approximated by templates. These techniques use the flat-sky approximation.

[ascl:1505.025]
pyMCZ: Oxygen abundances calculations and uncertainties from strong-line flux measurements

Bianco, Federica B.; Modjaz, Maryam; Oh, Seung Man; Fierroz, David; Liu, Yuqian; Kewley, Lisa; Graur, Or

pyMCZ calculates metallicity according to a number of strong line metallicity diagnostics from spectroscopy line measurements and obtain uncertainties from the line flux errors in a Monte Carlo framework. Given line flux measurements and their uncertainties, pyMCZ produces synthetic distributions for the oxygen abundance in up to 13 metallicity scales simultaneously, as well as for E(B-V), and estimates their median values and their 68% confidence regions. The code can output the full MC distributions and their kernel density estimates.

[ascl:1610.016]
PyMC3: Python probabilistic programming framework

PyMC3 performs Bayesian statistical modeling and model fitting focused on advanced Markov chain Monte Carlo and variational fitting algorithms. It offers powerful sampling algorithms, such as the No U-Turn Sampler, allowing complex models with thousands of parameters with little specialized knowledge of fitting algorithms, intuitive model specification syntax, and optimization for finding the maximum a posteriori (MAP) point. PyMC3 uses Theano to compute gradients via automatic differentiation as well as compile probabilistic programs on-the-fly to C for increased speed.

[ascl:1506.005]
PyMC: Bayesian Stochastic Modelling in Python

PyMC is a python module that implements Bayesian statistical models and fitting algorithms, including Markov chain Monte Carlo. Its flexibility and extensibility make it applicable to a large suite of problems. Along with core sampling functionality, PyMC includes methods for summarizing output, plotting, goodness-of-fit and convergence diagnostics.

[ascl:1906.022]
pyLIMA: Microlensing modeling package

pyLIMA (python Lightcurve Identification and Microlensing Analysis) fits microlensing lightcurves and derives the physical quantities of lens systems. The package provides microlensing modeling, and the magnification estimation for high cadence lightcurves has been optimized. pyLIMA is designed to make microlensing modeling and event simulation widely available to the community.

[ascl:1612.018]
pylightcurve: Exoplanet lightcurve model

pylightcurve is a model for light-curves of transiting planets. It uses the four coefficients law for the stellar limb darkening and returns the relative flux, *F*(*t*), as a function of the limb darkening coefficients, *a _{n}*, the

[ascl:1811.008]
Pylians: Python libraries for the analysis of numerical simulations

Pylians facilitates the analysis of numerical simulations (both N-body and hydro). This set of libraries, written in python, cython and C, compute power spectra, bispectra, and correlation functions, identifies voids, and populates halos with galaxies using an HOD. Pylians can also apply HI+H2 corrections to the output of hydrodynamic simulations, makes 21cm maps, computes DLAs column density distribution functions, and plots density fields.

[ascl:1510.003]
PyLDTk: Python toolkit for calculating stellar limb darkening profiles and model-specific coefficients for arbitrary filters

PyLDTk automates the calculation of custom stellar limb darkening (LD) profiles and model-specific limb darkening coefficients (LDC) using the library of PHOENIX-generated specific intensity spectra by Husser et al. (2013). It facilitates exoplanet transit light curve modeling, especially transmission spectroscopy where the modeling is carried out for custom narrow passbands. PyLDTk construct model-specific priors on the limb darkening coefficients prior to the transit light curve modeling. It can also be directly integrated into the log posterior computation of any pre-existing transit modeling code with minimal modifications to constrain the LD model parameter space directly by the LD profile, allowing for the marginalization over the whole parameter space that can explain the profile without the need to approximate this constraint by a prior distribution. This is useful when using a high-order limb darkening model where the coefficients are often correlated, and the priors estimated from the tabulated values usually fail to include these correlations.

[ascl:1708.016]
pyLCSIM: X-ray lightcurves simulator

pyLCSIM simulates X-ray lightcurves from coherent signals and power spectrum models. Coherent signals can be specified as a sum of one or more sinusoids, each with its frequency, pulsed fraction and phase shift; or as a series of harmonics of a fundamental frequency (each with its pulsed fraction and phase shift). Power spectra can be simulated from a model of the power spectrum density (PSD) using as a template one or more of the built-in library functions. The user can also define his/her custom models. Models are additive.

[ascl:1506.001]
pyKLIP: PSF Subtraction for Exoplanets and Disks

Wang, Jason J.; Ruffio, Jean-Baptise; De Rosa, Robert J.; Aguilar, Jonathan; Wolff, Schuyler G.; Pueyo, Laurent

pyKLIP subtracts out the stellar PSF to search for directly-imaged exoplanets and disks using a Python implementation of the Karhunen-Loève Image Projection (KLIP) algorithm. pyKLIP supports ADI, SDI, and ADI+SDI to model the stellar PSF and offers a large array of PSF subtraction parameters to optimize the reduction. pyKLIP relies on a minimal amount of dependencies (numpy, scipy, and astropy) and parallelizes the KLIP algorithm to speed up the reduction. pyKLIP supports GPI and P1640 data and can interface with other data sources with the addition of new modules. It also can inject simulated planets and disks as well as automatically search for point sources in PSF-subtracted data.

[ascl:1208.004]
PyKE: Reduction and analysis of Kepler Simple Aperture Photometry data

PyKE is a python-based PyRAF package that can also be run as a stand-alone program within a unix-based shell without compiling against PyRAF. It is a group of tasks developed for the reduction and analysis of Kepler Simple Aperture Photometry (SAP) data of individual targets with individual characteristics. The main purposes of these tasks are to i) re-extract light curves from manually-chosen pixel apertures and ii) cotrend and/or detrend the data in order to reduce or remove systematic noise structure using methods tunable to user and target-specific requirements. PyKE is an open source project and contributions of new tasks or enhanced functionality of existing tasks by the community are welcome.

[ascl:1511.005]
pyhrs: Spectroscopic data reduction package for SALT

The pyhrs package reduces data from the High Resolution Spectrograph (HRS) on the Southern African Large Telescope (SALT). HRS is a dual-beam, fiber fed echelle spectrectrograph with four modes of operation: low (R~16000), medium (R~34000), high (R~65000), and high stability (R~65000). pyhrs, written in Python, includes all of the steps necessary to reduce HRS low, medium, and high resolution data; this includes basic CCD reductions, order identification, wavelength calibration, and extraction of the spectra.

[ascl:1907.004]
pyGTC: Parameter covariance plots

pyGTC creates giant triangle confusogram (GTC) plots. Triangle plots display the results of a Monte-Carlo Markov Chain (MCMC) sampling or similar analysis. The recovered parameter constraints are displayed on a grid in which the diagonal shows the one-dimensional posteriors (and, optionally, priors) and the lower-left triangle shows the pairwise projections. Such plots are useful for seeing the parameter covariances along with the priors when fitting a model to data.

[ascl:1603.013]
PyGSM: Python interface to the Global Sky Model

PyGSM is a Python interface for the Global Sky Model (GSM, ascl:1011.010). The GSM is a model of diffuse galactic radio emission, constructed from a variety of all-sky surveys spanning the radio band (e.g. Haslam and WMAP). PyGSM uses the GSM to generate all-sky maps in Healpix format of diffuse Galactic radio emission from 10 MHz to 94 GHz. The PyGSM module provides visualization utilities, file output in FITS format, and the ability to generate observed skies for a given location and date. PyGSM requires Healpy, PyEphem (ascl:1112.014), and AstroPy (ascl:1304.002).

[ascl:1611.013]
pyGMMis: Mixtures-of-Gaussians density estimation method

pyGMMis is a mixtures-of-Gaussians density estimation method that accounts for arbitrary incompleteness in the process that creates the samples as long as the incompleteness is known over the entire feature space and does not depend on the sample density (missing at random). pyGMMis uses the Expectation-Maximization procedure and generates its best guess of the unobserved samples on the fly. It can also incorporate an uniform "background" distribution as well as independent multivariate normal measurement errors for each of the observed samples, and then recovers an estimate of the error-free distribution from which both observed and unobserved samples are drawn. The code automatically segments the data into localized neighborhoods, and is capable of performing density estimation with millions of samples and thousands of model components on machines with sufficient memory.

[ascl:1402.021]
PyGFit: Python Galaxy Fitter

PyGFit measures PSF-matched photometry from images with disparate pixel scales and PSF sizes; its primary purpose is to extract robust spectral energy distributions (SEDs) from crowded images. It fits blended sources in crowded, low resolution images with models generated from a higher resolution image, thus minimizing the impact of crowding and also yielding consistently measured fluxes in different filters which minimizes systematic uncertainty in the final SEDs.

[ascl:1411.001]
pyGadgetReader: GADGET snapshot reader for python

pyGadgetReader is a universal GADGET snapshot reader for python that supports type-1, type-2, HDF5, and TIPSY (ascl:1111.015) binary formats. It additionally supports reading binary outputs from FoF_Special, P-StarGroupFinder, Rockstar (ascl:1210.008), and Rockstar-Galaxies.

[ascl:1811.014]
pygad: Analyzing Gadget Simulations with Python

pygad provides a framework for dealing with Gadget snapshots. The code reads any of the many different Gadget (ascl:0003.001) formats, allows easy masking snapshots to particles of interest, decorates the data blocks with units, allows to add automatically updating derived blocks, and provides several binning and plotting routines, among other tasks, to provide convenient, intuitive handling of the Gadget data without the need to worry about technical details. pygad provides access to single stellar population (SSP) models, has an interface to Rockstar (ascl:1210.008) output files, provides its own friends-of-friends (FoF) finder, calculates spherical overdensities, and has a sub-module to generate mock absorption lines.

[ascl:1103.012]
Pyflation: Second Order Perturbations During Inflation Beyond Slow-roll

Pyflation calculates cosmological perturbations during an inflationary expansion of the universe. The modules in the pyflation Python package can be used to run simulations of different scalar field models of the early universe. The main classes are contained in the cosmomodels module and include simulations of background fields and first order and second order perturbations. The sourceterm package contains modules required for the computation of the term required for the evolution of second order perturbations.

Alongside the Python package, the bin directory contains Python scripts which can run first and second order simulations. A helper script called pyflation-qsubstart.py sets up a full second order run (including background, first order and source calculations) to be used on queueing system which contains the qsub executable (e.g. a Rocks cluster).

[ascl:1207.009]
PyFITS: Python FITS Module

Barrett, Paul; Hsu, J. C.; Hanley, Chris; Taylor, James; Droettboom, Michael; Bray, Erik M.; Hack, Warren; Greenfield, Perry; Wyckoff, Eric; Jedrzejewski, Robert; De La Pena, Michele; Hodge, Phil

PyFITS provides an interface to FITS formatted files in the Python scripting language and PyRAF, the Python-based interface to IRAF. It is useful both for interactive data analysis and for writing analysis scripts in Python using FITS files as either input or output. PyFITS is a development project of the Science Software Branch at the Space Telescope Science Institute.

**PyFITS has been deprecated. Please see Astropy**.

[ascl:1403.002]
pyExtinction: Atmospheric extinction

The Python script/package pyExtinction computes and plots total atmospheric extinction from decomposition into physical components (Rayleigh attenuation, ozone absorption, aerosol extinction). Its default extinction parameters are adapted to mean Mauna Kea summit conditions.

[ascl:1609.025]
PYESSENCE: Generalized Coupled Quintessence Linear Perturbation Python Code

PYESSENCE evolves linearly perturbed coupled quintessence models with multiple (cold dark matter) CDM fluid species and multiple DE (dark energy) scalar fields, and can be used to generate quantities such as the growth factor of large scale structure for any coupled quintessence model with an arbitrary number of fields and fluids and arbitrary couplings.

[ascl:1112.014]
PyEphem: Astronomical Ephemeris for Python

PyEphem provides scientific-grade astronomical computations for the Python programming language. Given a date and location on the Earth’s surface, it can compute the positions of the Sun and Moon, of the planets and their moons, and of any asteroids, comets, or earth satellites whose orbital elements the user can provide. Additional functions are provided to compute the angular separation between two objects in the sky, to determine the constellation in which an object lies, and to find the times at which an object rises, transits, and sets on a particular day.

The numerical routines that lie behind PyEphem are those from the wonderful XEphem astronomy application, whose author, Elwood Downey, generously gave permission for us to use them as the basis for PyEphem.

[ascl:1401.005]
PyDrizzle: Python version of Drizzle

PyDrizzle provides a semi-automated interface for computing the parameters necessary for running Drizzle. PyDrizzle performs the task of determining the parameters necessary for aligning images based on the WCS information in the input image headers, as well as any supplemental alignment information provided in shift files, and combines the images onto the same WCS. Though it does not identify cosmic rays, it has the ability to ignore pixels flagged as bad, such as pixels identified by other programs as affected by cosmic rays.

[submitted]
pydftools: Distribution function fitting in Python

pydftools is a pure-python port of the dftools R package (ascl:1805.002), which finds the most likely P parameters of a D-dimensional distribution function (DF) generating N objects, where each object is specified by D observables with measurement uncertainties. For instance, if the objects are galaxies, it can fit a MF (P=1), a mass-size distribution (P=2) or the mass-spin-morphology distribution (P=3). Unlike most common fitting approaches, this method accurately accounts for measurement in uncertainties and complex selection functions. Though this package imitates the dftools package quite closely while being as Pythonic as possible, it has not implemented 2D+ nor non-parametric.

[ascl:1509.010]
PyCS : Python Curve Shifting

PyCS is a software toolbox to estimate time delays between multiple images of strongly lensed quasars, from resolved light curves such as obtained by the COSMOGRAIL monitoring program. The pycs package defines a collection of classes and high level functions, that you can script in a flexible way. PyCS makes it easy to compare different point estimators (including your own) without much code integration. The package heavily depends on numpy, scipy, and matplotlib.

[ascl:1810.008]
pycraf: Spectrum-management compatibility

The pycraf Python package provides functions and procedures for spectrum-management compatibility studies, such as calculating the interference levels at a radio telescope produced from a radio broadcasting tower. It includes an implementation of ITU-R Recommendation P.452-16 for calculating path attenuation for the distance between an interferer and the victim service. It supports NASA's Shuttle Radar Topography Mission (SRTM) data for height-profile generation, includes a full implementation of ITU-R Rec. P.676-10, which provides two atmospheric models to calculate the attenuation for paths through Earth's atmosphere, and provides various antenna patterns necessary for compatibility studies (e.g., RAS, IMT, fixed-service links). The package can also convert power flux densities, field strengths, transmitted and received powers at certain distances and frequencies into each other.

[ascl:1210.027]
PyCosmic: Detecting cosmics in CALIFA and other fiber-fed integral-field spectroscopy datasets

The detection of cosmic ray hits (cosmics) in fiber-fed integral-field spectroscopy (IFS) data of single exposures is a challenging task because of the complex signal recorded by IFS instruments. Existing detection algorithms are commonly found to be unreliable in the case of IFS data, and the optimal parameter settings are usually unknown a priori for a given dataset. The Calar Alto legacy integral field area (CALIFA) survey generates hundreds of IFS datasets for which a reliable and robust detection algorithm for cosmics is required as an important part of the fully automatic CALIFA data reduction pipeline. PyCosmic combines the edge-detection algorithm of L.A.Cosmic with a point-spread function convolution scheme. PyCosmic is the only algorithm that achieves an acceptable detection performance for CALIFA data. Only for strongly undersampled IFS data does L.A.Cosmic exceed the performance of PyCosmic by a few percent. Thus, PyCosmic appears to be the most versatile cosmics detection algorithm for IFS data.

[ascl:1311.002]
PyCOOL: Cosmological Object-Oriented Lattice code

PyCOOL is a Python + CUDA program that solves the evolution of interacting scalar fields in an expanding universe. PyCOOL uses modern GPUs to solve this evolution and to make the computation much faster. The code includes numerous post-processing functions that provide useful information about the cosmological model, including various spectra and statistics of the fields.

[ascl:1509.007]
pycola: N-body COLA method code

pycola is a multithreaded Python/Cython N-body code, implementing the Comoving Lagrangian Acceleration (COLA) method in the temporal and spatial domains, which trades accuracy at small-scales to gain computational speed without sacrificing accuracy at large scales. This is especially useful for cheaply generating large ensembles of accurate mock halo catalogs required to study galaxy clustering and weak lensing. The COLA method achieves its speed by calculating the large-scale dynamics exactly using LPT while letting the N-body code solve for the small scales, without requiring it to capture exactly the internal dynamics of halos.

[ascl:1304.020]
pyCloudy: Tools to manage astronomical Cloudy photoionization code

PyCloudy is a Python library that handles input and output files of the Cloudy photoionization code (Gary Ferland). It can also generate 3D nebula from various runs of the 1D Cloudy code. pyCloudy allows you to:

- define and write input file(s) for Cloudy code. As you can have it in a code, you may generate automatically sets of input files, changing parameters from one to the other.
- read the Cloudy output files and play with the data: you will be able to plot line emissivity ratio vs. the radius of the nebula, the electron temperature, or any Cloudy output.
- build pseudo-3D models, a la Cloudy_3D, by running a set of models, changing parameters (e.g. inner radius, density) following angular laws, reading the outputs of the set of models and interpolating the results (Te, ne, line emissivities) in a 3D cube.

[ascl:1805.032]
PyCCF: Python Cross Correlation Function for reverberation mapping studies

PyCCF emulates a Fortran program written by B. Peterson for use with reverberation mapping. The code cross correlates two light curves that are unevenly sampled using linear interpolation and measures the peak and centroid of the cross-correlation function. In addition, it is possible to run Monto Carlo iterations using flux randomization and random subset selection (RSS) to produce cross-correlation centroid distributions to estimate the uncertainties in the cross correlation results.

[ascl:1805.030]
PyCBC: Gravitational-wave data analysis toolkit

PyCBC analyzes data from gravitational-wave laser interferometer detectors, finds signals, and studies their parameters. It contains algorithms that can detect coalescing compact binaries and measure the astrophysical parameters of detected sources. PyCBC was used in the first direct detection of gravitational waves by LIGO and is used in the ongoing analysis of LIGO and Virgo data.

[ascl:1204.002]
pyBLoCXS: Bayesian Low-Count X-ray Spectral analysis

Siemiginowska, Aneta; Kashyap, Vinay; Refsdal, Brian; van Dyk, David; Connors, Alanna; Park, Taeyoung

pyBLoCXS is a sophisticated Markov chain Monte Carlo (MCMC) based algorithm designed to carry out Bayesian Low-Count X-ray Spectral (BLoCXS) analysis in the Sherpa environment. The code is a Python extension to Sherpa that explores parameter space at a suspected minimum using a predefined Sherpa model to high-energy X-ray spectral data. pyBLoCXS includes a flexible definition of priors and allows for variations in the calibration information. It can be used to compute posterior predictive p-values for the likelihood ratio test. The pyBLoCXS code has been tested with a number of simple single-component spectral models; it should be used with great care in more complex settings.

[ascl:1502.007]
PyBDSF: Python Blob Detection and Source Finder

PyBDSF (Python Blob Detector and Source Finder, formerly PyBDSM) decomposes radio interferometry images into sources and makes their properties available for further use. PyBDSF can decompose an image into a set of Gaussians, shapelets, or wavelets as well as calculate spectral indices and polarization properties of sources and measure the psf variation across an image. PyBDSF uses an interactive environment based on CASA (ascl:1107.013); PyBDSF may also be used in Python scripts.

[ascl:1807.003]
PyAutoLens: Strong lens modeling

PyAutoLens models and analyzes galaxy-scale strong gravitational lenses. This automated module suite simultaneously models the lens galaxy's light and mass while reconstructing the extended source galaxy on an adaptive pixel-grid. Source-plane discretization is amorphous, adapting its clustering and regularization to the intrinsic properties of the lensed source. The lens's light is fitted using a superposition of Sersic functions, allowing PyAutoLens to cleanly deblend its light from the source. Bayesian model comparison is used to automatically chose the complexity of the light and mass models. PyAutoLens provides accurate light, mass, and source profiles inferred for data sets representative of both existing Hubble imaging and future Euclid wide-field observations.

[ascl:1707.003]
pyaneti: Multi-planet radial velocity and transit fitting

Pyaneti is a multi-planet radial velocity and transit fit software. The code uses Markov chain Monte Carlo (MCMC) methods with a Bayesian approach and a parallelized ensemble sampler algorithm in Fortran which makes the code fast. It creates posteriors, correlations, and ready-to-publish plots automatically, and handles circular and eccentric orbits. It is capable of multi-planet fitting and handles stellar limb darkening, systemic velocities for multiple instruments, and short and long cadence data, and offers additional capabilities.

[ascl:1806.007]
PyAMOR: AMmOnia data Reduction

PyAMOR models spectra of low level ammonia transitions (between (J,K)=(1,1) and (5,5)) and derives parameters such as intrinsic linewidth, optical depth, and rotation temperature. For low S/N or low spectral resolution data, the code uses cross-correlation between a model and a regridded spectrum (e.g. 10 times smaller channel width) to find the velocity, then fixes it and runs the minimization process. For high S/N data, PyAMOR runs with the velocity as a free parameter.

[ascl:1906.010]
PyA: Python astronomy-related packages

Czesla, Stefan; Schröter, Sebastian; Schneider, Christian P.; Huber, Klaus F.; Pfeifer, Fabian; Andreasen, Daniel T.; Zechmeister, Mathias

The PyA (PyAstronomy) suite of astronomy-related packages includes a convenient fitting package that provides support for minimization and MCMC sampling, a set of astrophysical models (*e.g.*, transit light-curve modeling), and algorithms for timing analysis such as the Lomb-Scargle and the Generalized Lomb-Scargle periodograms.

[ascl:1905.002]
Py4CAtS: PYthon for Computational ATmospheric Spectroscopy

Py4CAtS (PYthon scripts for Computational ATmospheric Spectroscopy) implements the individual steps of an infrared or microwave radiative transfer computation in separate scripts (and corresponding functions) to extract lines of relevant molecules in the spectral range of interest, compute line-by-line cross sections for given pressure(s) and temperature(s), combine cross sections to absorption coefficients and optical depths, and integrate along the line-of-sight to transmission and radiance/intensity. The code is a Python re-implementation of the Fortran code GARLIC (Generic Atmospheric Radiation Line-by-line Code) and uses the Numeric/Scientific Python modules for computationally-intensive highly optimized array-processing. Py4CAtS can be used in the console/terminal, inside the (I)Python interpreter, and in Jupyter notebooks.

[ascl:1712.003]
Py-SPHViewer: Cosmological simulations using Smoothed Particle Hydrodynamics

Py-SPHViewer visualizes and explores N-body + Hydrodynamics simulations. The code interpolates the underlying density field (or any other property) traced by a set of particles, using the Smoothed Particle Hydrodynamics (SPH) interpolation scheme, thus producing not only beautiful but also useful scientific images. Py-SPHViewer enables the user to explore simulated volumes using different projections. Py-SPHViewer also provides a natural way to visualize (in a self-consistent fashion) gas dynamical simulations, which use the same technique to compute the interactions between particles.

[ascl:1808.009]
py-sdm: Support Distribution Machines

py-sdm (Support Distribution Machines) is a Python implementation of nonparametric nearest-neighbor-based estimators for divergences between distributions for machine learning on sets of data rather than individual data points. It treats points of sets of data as samples from some unknown probability distribution and then statistically estimates the distance between those distributions, such as the KL divergence, the closely related Rényi divergence, L2 distance, or other similar distances.

[ascl:1806.032]
pwv_kpno: Modeling atmospheric absorption

pwv_kpno provides models for the atmospheric transmission due to precipitable water vapor (PWV) at user specified sites. Atmospheric transmission in the optical and near-infrared is highly dependent on the PWV column density along the line of sight. The pwv_kpno package uses published SuomiNet data in conjunction with MODTRAN models to determine the modeled, time-dependent atmospheric transmission between 3,000 and 12,000 Å. By default, models are provided for Kitt Peak National Observatory (KPNO). Additional locations can be added by the user for any of the hundreds of SuomiNet locations worldwide.

[ascl:1704.001]
pwkit: Astronomical utilities in Python

pwkit is a collection of miscellaneous astronomical utilities in Python, with an emphasis on radio astronomy, reading and writing various data formats, and convenient command-line utilities. Utilities include basic astronomical calculations, data visualization tools such as mapping arbitrary data to color scales and tracing contours, and data input and output utilities such as streaming output from other programs.

[ascl:1210.026]
PVS-GRMHD: Conservative GRMHD Primitive Variable Solvers

Conservative numerical schemes for general relativistic magnetohydrodynamics (GRMHD) require a method for transforming between "conserved'' variables such as momentum and energy density and "primitive" variables such as rest-mass density, internal energy, and components of the four-velocity. The forward transformation (primitive to conserved) has a closed-form solution, but the inverse transformation (conserved to primitive) requires the solution of a set of five nonlinear equations. This code performs the inversion.

[ascl:1608.010]
pvextractor: Position-Velocity Diagram Extractor

Given a path defined in sky coordinates and a spectral cube, pvextractor extracts a slice of the cube along that path and along the spectral axis to produce a position-velocity or position-frequency slice. The path can be defined programmatically in pixel or world coordinates, and can also be drawn interactively using a simple GUI. Pvextractor is the main function, but also includes a few utilities related to header trimming and parsing.

[ascl:1307.019]
PURIFY: Tools for radio-interferometric imaging

PURIFY is a collection of routines written in C that implements different tools for radio-interferometric imaging including file handling (for both visibilities and fits files), implementation of the measurement operator and set-up of the different optimization problems used for image deconvolution. The code calls the generic Sparse OPTimization (SOPT) package to solve the imaging optimization problems.

[ascl:1110.014]
pureS2HAT: S 2HAT-based Pure E/B Harmonic Transforms

The pS2HAT routines allow efficient, parallel calculation of the so-called 'pure' polarized multipoles. The computed multipole coefficients are equal to the standard pseudo-multipoles calculated for the apodized sky maps of the Stokes parameters Q and U subsequently corrected by so-called counterterms. If the applied apodizations fullfill certain boundary conditions, these multipoles correspond to the pure multipoles. Pure multipoles of one type, i.e., either E or B, are ensured not to contain contributions from the other one, at least to within numerical artifacts. They can be therefore further used in the estimation of the sky power spectra via the pseudo power spectrum technique, which has to however correctly account for the applied apodization on the one hand, and the presence of the counterterms, on the other.

In addition, the package contains the routines permitting calculation of the spin-weighted apodizations, given an input scalar, i.e., spin-0 window. The former are needed to compute the counterterms. It also provides routines for maps and window manipulations. The routines are written in C and based on the S2HAT library, which is used to perform all required spherical harmonic transforms as well as all inter-processor communication. They are therefore parallelized using MPI and follow the distributed-memory computational model. The data distribution patterns, pixelization choices, conventions etc are all as those assumed/allowed by the S2HAT library.

[ascl:1807.022]
PUMA: Low-frequency radio catalog cross-matching

PUMA (Positional Update and Matching Algorithm) cross-matches low-frequency radio catalogs using a Bayesian positional probability with spectral matching criteria. The code reliably finds the correct spectral indices of sources and recovers ionospheric offsets. PUMA can be used to facilitate all-sky cross-matches with further constraints applied for other science goals.

[ascl:1606.013]
Pulse Portraiture: Pulsar timing

Pulse Portraiture is a wideband pulsar timing code written in python. It uses an extension of the FFTFIT algorithm (Taylor 1992) to simultaneously measure a phase (TOA) and dispersion measure (DM). The code includes a Gaussian-component-based portrait modeling routine. The code uses the python interface to the pulsar data analysis package PSRCHIVE (ascl:1105.014) and also requires the non-linear least-squares minimization package lmfit (ascl:1606.014).

[ascl:1811.020]
PulsarHunter: Searching for and confirming pulsars

Pulsarhunter searches for and confirms pulsars; it provides a set of time domain optimization tools for processing timeseries data produced by SIGPROC (ascl:1107.016). The software can natively write candidate lists for JReaper (included in the package), removing the need to manually import candidates into JReaper; JReaper also reads the PulsarHunter candidate file format.

[ascl:1812.017]
psrqpy: Python module to query the ATNF Pulsar Catalogue

psrqpy directly queries the Australia Telescope National Facility (ATNF) Pulsar Catalogue by downloading and parsing the full catalog database, which is cached and can be reused. The module assists astronomers who want access to the latest pulsar information via a script rather than through the standard web interface.

[ascl:1501.006]
PsrPopPy: Pulsar Population Modelling Programs in Python

PsrPopPy is a Python implementation of the Galactic population and evolution of radio pulsars modelling code PSRPOP.

[ascl:1107.019]
PSRPOP: Pulsar Population Modelling Programs

PSRPOP is a package developed to model the Galactic population and evolution of radio pulsars. It is a collection of modules written in Fortran77 for an analysis of a large sample of pulsars detected by the Parkes Multibeam Pulsar Survey. The main programs are: 1.) populate, which creates a model Galaxy of pulsars distributed according according to various assumptions; 2.) survey, which searches the model galaxies generated using populate using realistic models of pulsar surveys; and 3.) visualize, a Tk/PGPLOT script to plot various aspects of model detected pulsars from survey. A sample screenshot from visualize can be found here.

[ascl:1105.014]
PSRCHIVE: Development Library for the Analysis of Pulsar Astronomical Data

PSRCHIVE is an Open Source C++ development library for the analysis of pulsar astronomical data. It implements an extensive range of algorithms for use in pulsar timing, polarimetric calibration, single-pulse analyses, RFI mitigation, scintillation studies, etc. These tools are utilized by a powerful suite of user-end programs that come with the library.

[ascl:1710.020]
PSPLINE: Princeton Spline and Hermite cubic interpolation routines

PSPLINE is a collection of Spline and Hermite interpolation tools for 1D, 2D, and 3D datasets on rectilinear grids. Spline routines give full control over boundary conditions, including periodic, 1st or 2nd derivative match, or divided difference-based boundary conditions on either end of each grid dimension. Hermite routines take the function value and derivatives at each grid point as input, giving back a representation of the function between grid points. Routines are provided for creating Hermite datasets, with appropriate boundary conditions applied. The 1D spline and Hermite routines are based on standard methods; the 2D and 3D spline or Hermite interpolation functions are constructed from 1D spline or Hermite interpolation functions in a straightforward manner. Spline and Hermite interpolation functions are often much faster to evaluate than other representations using e.g. Fourier series or otherwise involving transcendental functions.

[ascl:1010.011]
PSpectRe: A Pseudo-Spectral Code for (P)reheating

PSpectRe, written in C++, uses Fourier-space pseudo-spectral methods to evolve interacting scalar fields in an expanding universe. The code is optimized for the analysis of parametric resonance in the post-inflationary universe and provides an alternative to finite differencing codes. PSpectRe has both second- (Velocity-Verlet) and fourth-order (Runge-Kutta) time integrators. In some circumstances PSpectRe obtains reliable results while using substantially fewer points than a finite differencing code by computing the post-resonance equation of state. PSpectRe is designed to be easily extended to other problems in early-universe cosmology, including the generation of gravitational waves during phase transitions and pre-inflationary bubble collisions.

[ascl:1705.013]
PSOAP: Precision Spectroscopic Orbits A-Parametrically

PSOAP (Precision Spectroscopic Orbits A-Parametrically) uses Gaussian processes to infer component spectra of single-lined and double-lined spectroscopic binaries, while simultaneously exploring the posteriors of the orbital parameters and the spectra themselves. PSOAP accounts for the natural λ-covariances in each spectrum, thus providing a natural "de-noising" of the spectra typically offered by Fourier techniques.

[ascl:1208.005]
PSM: Planck Sky Model

Ashdown, Mark; Aumont, Jonathan; Baccigalupi, Carlo; Banday, Anthony; Basak, Soumen; Bernard, Jean-Philippe; Betoule, Marc; Bouchet, François; Castex, Guillaume; Clements, Dave; Da Silva, Antonio; De Zotti, Gianfranco; Delabrouille, Jacques; Dickinson, Clive; Dodu, Fabrice; Dolag, Klaus; Elsner, Franz; Fauvet, Lauranne; Faÿ, Gilles; Giardino, Giovanna; Gonzalez-Nuevo, Joaquin; le Jeune, Maude; Leach, Samuel; Lesgourgues, Julien; Liguori, Michele; Macias, Juan; Massardi, Marcella; Matarrese, Sabino; Mazzotta, Pasquale; Melin, Jean-Baptiste; Miville-Deschênes, Marc-Antoine; Montier, Ludovic; Mottet, Sylvain; Paladini, Roberta; Partridge, Bruce; Piffaretti, Rocco; Prézeau, Gary; Prunet, Simon; Ricciardi, Sara; Roman, Matthieu; Schaefer, Bjorn; Toffolatti, Luigi

The Planck Sky Model (PSM) is a global representation of the multi-component sky at frequencies ranging from a few GHz to a few THz. It summarizes in a synthetic way as much of our present knowledge as possible of the GHz sky. PSM is a complete and versatile set of programs and data that can be used for the simulation or the prediction of sky emission in the frequency range of typical CMB experiments, and in particular of the Planck sky mission. It was originally developed as part of the activities of Planck component separation Working Group (or "Working Group 2" - WG2), and of the ADAMIS team at APC.

PSM gives users the opportunity to investigate the model in some depth: look at its parameters, visualize its predictions for all individual components in various formats, simulate sky emission compatible with a given parameter set, and observe the modeled sky with a synthetic instrument. In particular, it makes possible the simulation of sky emission maps as could be plausibly observed by Planck or other CMB experiments that can be used as inputs for the development and testing of data processing and analysis techniques.

[ascl:1301.001]
PSFEx: Point Spread Function Extractor

PSFEx (“PSF Extractor”) extracts models of the Point Spread Function (PSF) from FITS images processed with SExtractor and measures the quality of images. The generated PSF models can be used for model-fitting photometry or morphological analyses.

[ascl:1905.025]
Prospector: Stellar population inference from spectra and SEDs

Prospector conducts principled inference of stellar population properties from photometric and/or spectroscopic data. The code combine photometric and spectroscopic data rigorously using a flexible spectroscopic calibration model and infer high-dimensional stellar population properties using parameteric SFHs (with ensemble MCMC sampling). Prospector also constrains the linear combination of stellar population components that are present in a galaxy (e.g. non-parametric SFHs) using spectra and/or photometry, and fits individual stellar spectra using large interpolated grids.

[ascl:1306.005]
PROS: Multi-mission X-ray analysis software system

PROS is a multi-mission x-ray analysis software system designed to run under IRAF. The PROS software includes spatial, spectral, timing, data I/O and conversion routines, plotting applications, and general algorithms for performing arithmetic operations with imaging data.

[ascl:1904.025]
Properimage: Image coaddition and subtraction

Properimage processes astronomical image; it is specially written for coaddition and image subtraction. It performs the statistical proper-coadd of several images using a spatially variant PSF estimation, and also difference image analysis by several strategies developed by others. Most of the code is based on a class called SingleImage, which provides methods and properties for image processing such as PSF determination.

[ascl:1405.006]
PROPER: Optical propagation routines

PROPER simulates the propagation of light through an optical system using Fourier transform algorithms (Fresnel, angular spectrum methods). Available in IDL, Python, and Matlab, it includes routines to create complex apertures, aberrated wavefronts, and deformable mirrors. It is especially useful for the simulation of high contrast imaging telescopes (extrasolar planet imagers like TPF).

[ascl:1511.023]
PromptNuFlux: Prompt atmospheric neutrino flux calculator

PromptNuFlux computes the prompt atmospheric neutrino flux E3Φ(GeV2/(cm2ssr)), including the total associated theory uncertainty, for a range of energies between E=103 GeV and E=107.5 GeV. Results are available for five different parametrizations of the input cosmic ray flux: BPL, H3P, H3A, H14a, H14b.

[ascl:1805.023]
PROM7: 1D modeler of solar filaments or prominences

PROM7 is an update of PROM4 (ascl:1306.004) and computes simple models of solar prominences and filaments using Partial Radiative Distribution (PRD). The models consist of plane-parallel slabs standing vertically above the solar surface. Each model is defined by 5 parameters: temperature, density, geometrical thickness, microturbulent velocity and height above the solar surface. It solves the equations of radiative transfer, statistical equilibrium, ionization and pressure equilibria, and computes electron and hydrogen level population and hydrogen line profiles. Moreover, the code treats calcium atom which is reduced to 3 ionization states (Ca I, Ca II, CA III). Ca II ion has 5 levels which are useful for computing 2 resonance lines (H and K) and infrared triplet (to 8500 A).

[ascl:1306.004]
PROM4: 1D isothermal and isobaric modeler for solar prominences

PROM4 computes simple models of solar prominences which consist of plane-parallel slabs standing vertically above the solar surface. Each model is defined by 5 parameters: temperature, density, geometrical thickness, microturbulent velocity and height above the solar surface. PROM4 solves the equations of radiative transfer, statistical equilibrium, ionization and pressure equilibria, and computes electron and hydrogen level populations and hydrogen line profiles. Written in Fortran 90 and with two versions available (one with text in English, one with text in French), the code needs 64-bit arithmetic for real numbers.

PROM7 (ascl:1805.023) is a more recent version of this code.

[ascl:1804.006]
ProFound: Source Extraction and Application to Modern Survey Data

ProFound detects sources in noisy images, generates segmentation maps identifying the pixels belonging to each source, and measures statistics like flux, size, and ellipticity. These inputs are key requirements of ProFit (ascl:1612.004), our galaxy profiling package; these two packages used in unison semi-automatically profile large samples of galaxies. The key novel feature introduced in ProFound is that all photometry is executed on dilated segmentation maps that fully contain the identifiable flux, rather than using more traditional circular or ellipse-based photometry. Also, to be less sensitive to pathological segmentation issues, the de-blending is made across saddle points in flux. ProFound offers good initial parameter estimation for ProFit, and also segmentation maps that follow the sometimes complex geometry of resolved sources, whilst capturing nearly all of the flux. A number of bulge-disc decomposition projects are already making use of the ProFound and ProFit pipeline.

[ascl:1204.015]
PROFIT: Emission-line PROfile FITting routine

The PROFIT is an IDL routine to do automated fitting of emission-line profiles by Gaussian curves or Gauss-Hermite series optimized for use in Integral Field and Fabry-Perot data cubes. As output PROFIT gives two-dimensional FITS files for the emission-line flux distribution, centroid velocity, velocity dispersion and higher order Gauss-Hermite moments (h3 and h4).

[ascl:1612.004]
ProFit: Bayesian galaxy fitting tool

ProFit is a Bayesian galaxy fitting tool that uses the fast C++ image generation library libprofit (ascl:1612.003) and a flexible R interface to a large number of likelihood samplers. It offers a fully featured Bayesian interface to galaxy model fitting (also called profiling), using mostly the same standard inputs as other popular codes (e.g. GALFIT ascl:1104.010), but it is also able to use complex priors and a number of likelihoods.

[ascl:1705.010]
PROFILER: 1D galaxy light profile decomposition

Written in Python, PROFILER analyzes the radial surface brightness profiles of galaxies. It accurately models a wide range of galaxies and galaxy components, such as elliptical galaxies, the bulges of spiral and lenticular galaxies, nuclear sources, discs, bars, rings, and spiral arms with a variety of parametric functions routinely employed in the field (Sérsic, core-Sérsic, exponential, Gaussian, Moffat and Ferrers). In addition, Profiler can employ the broken exponential model (relevant for disc truncations or antitruncations) and two special cases of the edge-on disc model: namely along the major axis (in the disc plane) and along the minor axis (perpendicular to the disc plane).

[ascl:1608.011]
PROFFIT: Analysis of X-ray surface-brightness profiles

PROFFIT analyzes X-ray surface-brightness profiles for data from any X-ray instrument. It can extract surface-brightness profiles in circular or elliptical annuli, using constant or logarithmic bin size, from the image centroid, the surface-brightness peak, or any user-given center, and provides surface-brightness profiles in any circular or elliptical sectors. It offers background map support to extract background profiles, can excise areas using SAO DS9-compatible (ascl:0003.002) region files to exclude point sources, provides fitting with a number of built-in models, including the popular beta model, double beta, cusp beta, power law, and projected broken power law, uses chi-squared or C statistic, and can fit on the surface-brightness or counts data. It has a command-line interface similar to HEASOFT’s XSPEC (ascl:9910.005) package, provides interactive help with a description of all the commands, and results can be saved in FITS, ROOT or TXT format.

[ascl:1601.020]
ProC: Process Coordinator

Hovest, Wolfgang; Knoche, Jörg; Hell, Reinhard; Doerl, Uwe; Riller, Thomas; Matthai, Frank; Ensslin, Torsten; Rachen, Jörg; Robbers, Georg; Adorf, Hans-Martin; Reinecke, Martin; Bartelmann, Matthias

ProC (short for Process Coordinator) is a versatile workflow engine that allows the user to build, run and manage workflows with just a few clicks. It automatically documents every processing step, making every modification to data reproducible. ProC provides a graphical user interface for constructing complex data processing workflows out of a given set of computer programs. The user can, for example, specify that only data products which are affected by a change in the input data are updated selectively, avoiding unnecessary computations. The ProC suite is flexible and satisfies basic needs of data processing centers that have to be able to restructure their data processing along with the development of a project.

[ascl:1903.009]
PRF: Probabilistic Random Forest

PRF (Probabilistic Random Forest) is a machine learning algorithm for noisy datasets. The PRF is a modification of the long-established Random Forest (RF) algorithm, and takes into account uncertainties in the measurements (i.e., features) as well as in the assigned classes (i.e., labels). To do so, the Probabilistic Random Forest (PRF) algorithm treats the features and labels as probability distribution functions, rather than as deterministic quantities.

[ascl:1107.017]
PRESTO: PulsaR Exploration and Search TOolkit

PRESTO is a large suite of pulsar search and analysis software. It was primarily designed to efficiently search for binary millisecond pulsars from long observations of globular clusters (although it has since been used in several surveys with short integrations and to process a lot of X-ray data as well). To date, PRESTO has discovered well over a hundred and fifty pulsars, including approximately 100 recycled pulsars, about 80 of which are in binaries. It is written primarily in ANSI C, with many of the recent routines in Python.

Written with portability, ease-of-use, and memory efficiency in mind, it can currently handle raw data from the following pulsar machines or formats:

- PSRFITS search-format data (as from GUPPI at the GBT and the Mock Spectrometers at Arecibo)
- SPIGOT at the GBT
- Most Wideband Arecibo Pulsar Processor (WAPP) at Arecibo
- The Parkes and Jodrell Bank 1-bit filterbank formats
- Berkeley-Caltech Pulsar Machine (BCPM) at the GBT (may it RIP...)
- 8-bit filterbank format from SIGPROC (other formats will be added if required)
- A time series composed of single precision (i.e. 4-byte) floating point data
- Photon arrival times (or events) in ASCII or double-precision binary formats

[ascl:1305.006]
Pressure-Entropy SPH: Pressure-entropy smooth-particle hydrodynamics

Pressure-Entropy SPH, a modified version of GADGET-2, uses the Lagrangian “Pressure-Entropy” formulation of the SPH equations. This removes the spurious “surface tension” force substantially improving the treatment of fluid mixing and contact discontinuities. Pressure-Entropy SPH shows good performance in mixing experiments (e.g. Kelvin-Helmholtz & blob tests), with conservation maintained even in strong shock/blastwave tests, where formulations without manifest conservation produce large errors. This improves the treatment of sub-sonic turbulence and lessens the need for large kernel particle numbers.

[ascl:1112.016]
PREDICT: Satellite tracking and orbital prediction

PREDICT is an open-source, multi-user satellite tracking and orbital prediction program written under the Linux operating system. PREDICT provides real-time satellite tracking and orbital prediction information to users and client applications through:

- the system console
- the command line
- a network socket
- the generation of audio speech

[ascl:1710.024]
pred_loggs: Predicting individual galaxy G/S probability distributions

Eckert, Kathleen D.; Kannappan, Sheila J.; Stark, David V.; Moffett, Amanda J.; Norris, Mark A.; Snyder, Elaine M.; Hoversten, Erik A.

pred_loggs models the entire PGF probability density field, enabling iterative statistical modeling of upper limits and prediction of full G/S probability distributions for individual galaxies.

[ascl:1611.004]
PRECESSION: Python toolbox for dynamics of spinning black-hole binaries

PRECESSION is a comprehensive toolbox for exploring the dynamics of precessing black-hole binaries in the post-Newtonian regime. It allows study of the evolution of the black-hole spins along their precession cycles, performs gravitational-wave-driven binary inspirals using both orbit-averaged and precession-averaged integrations, and predicts the properties of the merger remnant through fitting formulas obtained from numerical-relativity simulations. PRECESSION can add the black-hole spin dynamics to larger-scale numerical studies such as gravitational-wave parameter estimation codes, population synthesis models to predict gravitational-wave event rates, galaxy merger trees and cosmological simulations of structure formation, and provides fast and reliable integration methods to propagate statistical samples of black-hole binaries from/to large separations where they form to/from small separations where they become detectable, thus linking gravitational-wave observations of spinning black-hole binaries to their astrophysical formation history. The code is also useful for computing initial parameters for numerical-relativity simulations targeting specific precessing systems.

[ascl:1210.002]
pPXF: Penalized Pixel-Fitting stellar kinematics extraction

pPXF is an IDL (and free GDL or FL) program which extracts the stellar kinematics or stellar population from absorption-line spectra of galaxies using the Penalized Pixel-Fitting method (pPXF) developed by Cappellari & Emsellem (2004, PASP, 116, 138). Additional features implemented in the pPXF routine include:

- Optimal template: Fitted together with the kinematics to minimize template-mismatch errors. Also useful to extract gas kinematics or derive emission-corrected line-strengths indexes. One can use synthetic templates to study the stellar population of galaxies via "Full Spectral Fitting" instead of using traditional line-strengths.
- Regularization of templates weights: To reduce the noise in the recovery of the stellar population parameters and attach a physical meaning to the output weights assigned to the templates in term of the star formation history (SFH) or metallicity distribution of an individual galaxy.
- Iterative sigma clipping: To clean the spectra from residual bad pixels or cosmic rays.
- Additive/multiplicative polynomials: To correct low frequency continuum variations. Also useful for calibration purposes.

[ascl:1507.009]
PPInteractions: Secondary particle spectra from proton-proton interactions

PPInteractions generates the secondary particle energy spectra produced in proton-proton interactions over the entire chosen energy range for any value of the primary proton spectral index by adjusting the low energy part of the spectra (below 0.1TeV) to the high energy end of the spectra (above 0.1TeV). This code is based on the parametrization of Kelner et al (2006), in which the normalization of the low energy part of the spectra is given only for 3 values of the primary proton spectral indices (2, 2.5, 3).

[ascl:1401.009]
PPF module for CAMB

The main CAMB code supports smooth dark energy models with constant equation of state and sound speed of one, or a quintessence model based on a potential. This modified code generalizes it to support a time-dependent equation of state w(a) that is allowed to cross the phantom divide, i.e. w=-1 multiple times by implementing a Parameterized Post-Friedmann(PPF) prescription for the dark energy perturbations.

[ascl:1110.017]
POWMES: Measuring the Power Spectrum in an N-body Simulation

POWMES is a F90 program to measure very accurately the power spectrum in a N-body simulation, using Taylor expansion of some order on the cosine and sine transforms. It can read GADGET format and requires FFTW2 to be installed.

[ascl:1805.001]
powerbox: Arbitrarily structured, arbitrary-dimension boxes and log-normal mocks

powerbox creates density grids (or boxes) with an arbitrary two-point distribution (i.e. power spectrum). The software works in any number of dimensions, creates Gaussian or Log-Normal fields, and measures power spectra of output fields to ensure consistency. The primary motivation for creating the code was the simple creation of log-normal mock galaxy distributions, but the methodology can be used for other applications.

[ascl:1807.021]
POWER: Python Open-source Waveform ExtractoR

POWER (Python Open-source Waveform ExtractoR) monitors the status and progress of numerical relativity simulations and post-processes the data products of these simulations to compute the gravitational wave strain at future null infinity.

[ascl:1411.021]
POSTMORTEM: Visibility data reduction and map making package

POSTMORTEM is the visibility data reduction and map making package from MRAO (Mullard Radio Astronomy Observatory) and is used with the Ryle and CLFST telescopes at Cambridge. It contains sub-systems for nonitoring telescope performance, displaying and editing the visibility data, performing calibrations, removing flux from interfering bright sources, and map-making. It requires PGPLOT (ascl:1103.002), SLALIB (ascl:1403.025), and NAG numerical routines, all of which are distributed with the STARLINK software collection (ascl:1110.012) or available separately.

[ascl:0202.001]
PopRatio: A program to calculate atomic level populations in astrophysical plasmas

PopRatio is a Fortran 90 code to calculate atomic level populations in astrophysical plasmas. The program solves the equations of statistical equilibrium considering all possible bound-bound processes: spontaneous, collisional or radiation induced (the later either directly or by fluorescence). There is no limit on the number of levels or in the number of processes that may be taken into account. The program may find a wide range of applicability in astronomical problems, such as interpreting fine-structure absorption lines or collisionally excited emission lines and also in calculating the cooling rates due to collisional excitation.

[ascl:1602.018]
POPPY: Physical Optics Propagation in PYthon

Perrin, Marshall; Long, Joseph; Douglas, Ewan; Sivaramakrishnan, Anand; Slocum, Christine; and others

POPPY (Physical Optics Propagation in PYthon) simulates physical optical propagation including diffraction. It implements a flexible framework for modeling Fraunhofer and Fresnel diffraction and point spread function formation, particularly in the context of astronomical telescopes. POPPY provides the optical modeling framework for WebbPSF (ascl:1504.007) and was developed as part of a simulation package for JWST, but is available separately and is broadly applicable to many kinds of imaging simulations.

[ascl:1805.011]
PoMiN: A Post-Minkowskian N-Body Solver

PoMiN is a lightweight N-body code based on the Post-Minkowskian N-body Hamiltonian of Ledvinka, Schafer, and Bicak, which includes General Relativistic effects up to first order in Newton's constant G, and all orders in the speed of light c. PoMiN is a single file written in C and uses a fourth-order Runge-Kutta integration scheme. PoMiN has also been written to handle an arbitrary number of particles (both massive and massless) with a computational complexity that scales as O(N^2).

[ascl:1502.011]
PolyChord: Nested sampling for cosmology

PolyChord is a Bayesian inference tool for the simultaneous calculation of evidences and sampling of posterior distributions. It is a variation on John Skilling's Nested Sampling, utilizing Slice Sampling to generate new live points. It performs well on moderately high dimensional (~100s D) posterior distributions, and can cope with arbitrary degeneracies and multimodality.

[ascl:1109.005]
PolSpice: Spatially Inhomogeneous Correlation Estimator for Temperature and Polarisation

PolSpice (aka Spice) is a tool to statistically analyze Cosmic Microwave Background (CMB) data, as well as any other diffuse data pixelized on the sphere.

This Fortran90 program measures the 2 point auto (or cross-) correlation functions w(θ) and the angular auto- (or cross-) power spectra C(l) from one or (two) sky map(s) of Stokes parameters (intensity I and linear polarisation Q and U). It is based on the fast Spherical Harmonic Transforms allowed by isolatitude pixelisations such as Healpix [for Npix pixels over the whole sky, and a C(l) computed up to l=lmax, PolSpice complexity scales like Npix1/2 lmax2 instead of Npix lmax2]. It corrects for the effects of the masks and can deal with inhomogeneous weights given to the pixels of the map. In the case of polarised data, the mixing of the E and B modes due to the cut sky and pixel weights can be corrected for to provide an unbiased estimate of the "magnetic" (B) component of the polarisation power spectrum. Most of the code is parallelized for shared memory (SMP) architecture using OpenMP.

[ascl:1603.018]
PolRadTran: Polarized Radiative Transfer Model Distribution

PolRadTran is a plane-parallel polarized radiative transfer model. It is used to compute the radiance exiting a vertically inhomogeneous atmosphere containing randomly-oriented particles. Both solar and thermal sources of radiation are considered. A direct method of incorporating the polarized scattering information is combined with the doubling and adding method to produce a relatively simple formulation.

[ascl:1405.014]
POLPACK: Imaging polarimetry reduction package

POLPACK maps the linear or circular polarization of extended astronomical objects, either in a single waveband, or in multiple wavebands (spectropolarimetry). Data from both single and dual beam polarimeters can be processed. It is part of the Starlink software collection (ascl:1110.012).

[ascl:1406.012]
POLMAP: Interactive data analysis package for linear spectropolarimetry

POLMAP provides routines for displaying and analyzing spectropolarimetry data that are not available in the complementary TSP package. Commands are provided to read and write TSP (ascl:1406.011) polarization spectrum format files from within POLMAP. This code is distributed as part of the Starlink software collection (ascl:1110.012).

[ascl:1807.001]
POLARIS: POLArized RadIation Simulator

POLARIS (POLArized RadIation Simulator) simulates the intensity and polarization of light emerging from analytical astrophysical models as well as complex magneto-hydrodynamic simulations on various grids. This 3D Monte-Carlo continuum radiative transfer code is written in C++ and is capable of performing dust heating, dust grain alignment, line radiative transfer, and synchrotron simulations to calculate synthetic intensity and polarization maps. The code makes use of a full set of physical quantities (density, temperature, velocity, magnetic field distribution, and dust grain properties as well as different sources of radiation) as input.

[ascl:1505.018]
POKER: P Of K EstimatoR

POKER (P Of K EstimatoR) estimates the angular power spectrum of a 2D map or the cross-power spectrum of two 2D maps in the flat sky limit approximation in a realistic data context: steep power spectrum, non periodic boundary conditions, arbitrary pixel resolution, non trivial masks and observation patch geometry.

[ascl:1408.005]
POET: Planetary Orbital Evolution due to Tides

POET (Planetary Orbital Evolution due to Tides) calculates the orbital evolution of a system consisting of a single star with a single planet in orbit under the influence of tides. The following effects are The evolutions of the semimajor axis of the orbit due to the tidal dissipation in the star and the angular momentum of the stellar convective envelope by the tidal coupling are taken into account. In addition, the evolution includes the transfer of angular momentum between the stellar convective and radiative zones, effect of the stellar evolution on the tidal dissipation efficiency, and stellar core and envelope spins and loss of stellar convective zone angular momentum to a magnetically launched wind. POET can be used out of the box, and can also be extended and modified.

[ascl:1907.006]
POCS: PANOPTES Observatory Control System

PANOPTES (Panoptic Astronomical Networked Observatories for a Public Transiting Exoplanets Survey) is a citizen science project for low cost, robotic detection of transiting exoplanets. POCS (PANOPTES Observatory Control System) is the main software driver for the PANOPTES telescope system, responsible for high-level control of the unit. POCS defines an Observatory class that automatically controls a commercially available equatorial mount, including image analysis and corresponding mount adjustment to obtain a percent-level photometric precision.

[ascl:1302.004]
pNbody: A python parallelized N-body reduction toolbox

pNbody is a parallelized python module toolbox designed to manipulate and interactively display very large N-body systems. It allows the user to perform complicated manipulations with only very few commands and to load an N-body system and explore it interactively using the python interpreter. pNbody may also be used in python scripts. pNbody contains graphical facilities for creating maps of physical values of the system, such as density, temperature, and velocities maps. Stereo capabilities are also implemented. pNbody is not limited by file format; the user may use a parameter file to redefine how to read a preferred format.

[ascl:1102.015]
PMFASTIC: Initial condition generator for PMFAST

PMFASTIC is a parallel initial condition generator, a slab decomposition Fortran 90 parallel cosmological initial condition generator for use with PMFAST. Files required for generating initial dark matter particle distributions and instructions are included, however one would require CMBFAST to create alternative transfer functions.

[ascl:1102.008]
PMFAST: Towards Optimal Parallel PM N-body Codes

The parallel PM N-body code PMFAST is cost-effective and memory-efficient. PMFAST is based on a two-level mesh gravity solver where the gravitational forces are separated into long and short range components. The decomposition scheme minimizes communication costs and allows tolerance for slow networks. The code approaches optimality in several dimensions. The force computations are local and exploit highly optimized vendor FFT libraries. It features minimal memory overhead, with the particle positions and velocities being the main cost. The code features support for distributed and shared memory parallelization through the use of MPI and OpenMP, respectively.

The current release version uses two grid levels on a slab decomposition, with periodic boundary conditions for cosmological applications. Open boundary conditions could be added with little computational overhead. Timing information and results from a recent cosmological production run of the code using a 3712^3 mesh with 6.4 x 10^9 particles are available.

[ascl:9909.001]
PMCode: Particle-Mesh Code for Cosmological Simulations

Particle-Mesh (PM) codes are still very useful tools for testing predictions of cosmological models in cases when extra high resolution is not very important. We release for public use a cosmological PM N-body code. The code is very fast and simple. We provide a complete package of routines needed to set initial conditions, to run the code, and to analyze the results. The package allows you to simulate models with numerous combinations of parameters: open/flat/closed background, with or without the cosmological constant, different values of the Hubble constant, with or without hot neutrinos, tilted or non-tilted initial spectra, different amount of baryons.

[ascl:1010.045]
PLUTO: A Code for Flows in Multiple Spatial Dimensions

PLUTO is a modular Godunov-type code intended mainly for astrophysical applications and high Mach number flows in multiple spatial dimensions. The code embeds different hydrodynamic modules and multiple algorithms to solve the equations describing Newtonian, relativistic, MHD, or relativistic MHD fluids in Cartesian or curvilinear coordinates. PLUTO is entirely written in the C programming language and can run on either single processor machines or large parallel clusters through the MPI library. A simple user-interface based on the Python scripting language is available to setup a physical problem in a quick and self-explanatory way. Computations may be carried on either static or adaptive (structured) grids, the latter functionality being provided through the Chombo adaptive mesh refinement library.

[ascl:1206.007]
Plumix: Generating mass segregated star clusters

Plumix is a small package for generating mass segregated star clusters. Its output can be directly used as input initial conditions for NBODY4 or NBODY6 code. Mass segregation stands as one of the most robust features of the dynamical evolution of self-gravitating star clusters. We formulate parametrized models of mass segregated star clusters in virial equilibrium. To this purpose we introduce mean inter-particle potentials for statistically described unsegregated systems and suggest a single-parameter generalization of its form which gives a mass-segregated state. Plumix is a numerical C-code generating the cluster according the algorithm given for construction of appropriate star cluster models. Their stability over several crossing-times is verified by following the evolution by means of direct N-body integration.

[ascl:1106.003]
PLplot: Cross-platform Software Package for Scientific Plots

PLplot is a cross-platform software package for creating scientific plots. To help accomplish that task it is organized as a core C library, language bindings for that library, and device drivers which control how the plots are presented in non-interactive and interactive plotting contexts. The PLplot core library can be used to create standard x-y plots, semi-log plots, log-log plots, contour plots, 3D surface plots, mesh plots, bar charts and pie charts. Multiple graphs (of the same or different sizes) may be placed on a single page, and multiple pages are allowed for those device formats that support them. PLplot has core support for Unicode. This means for our many Unicode-aware devices that plots can be labelled using the enormous selection of Unicode mathematical symbols. A large subset of our Unicode-aware devices also support complex text layout (CTL) languages such as Arabic, Hebrew, and Indic and Indic-derived CTL scripts such as Devanagari, Thai, Lao, and Tibetan. PLplot device drivers support a number of different file formats for non-interactive plotting and a number of different platforms that are suitable for interactive plotting. It is easy to add new device drivers to PLplot by writing a small number of device dependent routines.

[ascl:1907.009]
Plonk: Smoothed particle hydrodynamics data analysis and visualization

Plonk analyzes and visualizes smoothed particle hydrodynamics simulation data. It is built on the scientific Python ecosystem, including NumPy, Matplotlib, Cython, h5py, SymPy, and pandas. Plock's visualization module uses Splash (ascl:1103.004) to produce images using smoothed particle hydrodynamics interpolation. The code is modular and extendible, and can be scripted or used interactively.

[ascl:1903.014]
PLATON: PLanetary Atmospheric Transmission for Observer Noobs

PLATON (PLanetary Atmospheric Transmission for Observer Noobs) calculates transmission spectra for exoplanets and retrieves atmospheric characteristics based on observed spectra; it is based on ExoTransmit (ascl:1611.005). PLATON supports the most common atmospheric parameters, such as temperature, metallicity, C/O ratio, cloud-top pressure, and scattering slope. It also has less commonly included features, such as a Mie scattering cloud model and unocculted starspot corrections.

[ascl:1506.003]
PLATO Simulator: Realistic simulations of expected observations

Marcos-Arenal, P.; Zima, W.; De Ridder, J.; Aerts, C.; Huygen, R.; Samadi, R.; Green, J.; Piotto, G.; Salmon, S.; Catala, C.; Rauer, H.

PLATO Simulator is an end-to-end simulation software tool designed for the performance of realistic simulations of the expected observations of the PLATO mission but easily adaptable to similar types of missions. It models and simulates photometric time-series of CCD images by including models of the CCD and its electronics, the telescope optics, the stellar field, the jitter movements of the spacecraft, and all important natural noise sources.

[ascl:1906.019]
PlasmaPy: Core Python package for plasma physics

PlasmaPy Community; Murphy, Nicholas A.; Stańczak, Dominik; Kozlowski, Pawel M.; Langendorf, Samuel J.; Leonard, Andrew J.; Beckers, Jasper P.; Haggerty, Colby C.; Mumford, Stuart J.; Malhotra, Ritiek; Bessi, Ludovico; Carroll, Sean; Choubey, Apoorv; Díaz Pérez, Roberto; Einhorn, Leah; Fan, Thomas; Goudeau, Graham; Guidoni, Silvina; Hillairet, Julien; How, Poh Zi; Huang, Yi-Min; Humphrey, Nabil; Isupova, Maria; Kulshrestha, Siddharth; Kuszaj, Piotr; Munn, Joshua; Parashar, Tulasi; Patel, Neil; Raj, Raajit; Sherpa, Dawa Nurbu; Stansby, David; Tavant, Antoine; Xu, Sixue

PlasmaPy provides core functionality and a common framework for data visualization and analysis for plasma physics. It has modules for basic plasma physics calculations, running desktop-scale simulations to test preliminary ideas such as one-dimensional MHD/PIC or test particles, or comparing data from two different sources, such as simulations and spacecraft.

[ascl:1311.004]
PlanetPack: Radial-velocity time-series analysis tool

PlanetPack facilitates and standardizes the advanced analysis of radial velocity (RV) data for the goal of exoplanets detection, characterization, and basic dynamical N-body simulations. PlanetPack is a command-line interpreter that can run either in an interactive mode or in a batch mode of automatic script interpretation.

[ascl:1607.005]
Planetary3br: Three massive body resonance calculator

Given two planets P1 and P2 with arbitrary orbits, planetary3br calculates all possible semimajor axes that a third planet P0 can have in order for the system to be in a three body resonance; these are identified by the combination k0*P0 + k1*P1 + k2*P2. P1 and P2 are assumed to be not in an exact two-body resonance. The program also calculates three "strengths" of the resonance, one for each planet, which are only indicators of the dynamical relevance of the resonance on each planet. Sample input data are available along with the Fortran77 source code.

[ascl:1505.032]
Planck Level-S: Planck Simulation Package

The Planck simulation package takes a cosmological model specified by the user and calculates a potential CMB sky consistent with this model, including astrophysical foregrounds, and then performs a simulated observation of this sky. This Simulation embraces many instrumental effects such as beam convolution and noise. Alternatively, the package can simulate the observation of a provided sky model, generated by another program such as the Planck Sky Model software. The Planck simulation package does not only provide Planck-like data, it can also be easily adopted to mimic the properties of other existing and upcoming CMB experiments.

[ascl:1609.016]
PKDGRAV3: Parallel gravity code

Pkdgrav3 is an 𝒪(*N*) gravity calculation method; it uses a binary tree algorithm with fifth order fast multipole expansion of the gravitational potential, using cell-cell interactions. Periodic boundaries conditions require very little data movement and allow a high degree of parallelism; the code includes GPU acceleration for all force calculations, leading to a significant speed-up with respect to previous versions (ascl:1305.005). Pkdgrav3 also has a sophisticated time-stepping criterion based on an estimation of the local dynamical time.

[ascl:1305.005]
PkdGRAV2: Parallel fast-multipole cosmological code

PkdGRAV2 is a high performance N-body treecode for self-gravitating astrophysical simulations. It is designed to run efficiently in serial and on a wide variety of parallel computers including both shared memory and message passing architectures. It can spatially adapt to large ranges in particle densities, and temporally adapt to large ranges in dynamical timescales. The code uses a non-standard data structure for efficiently calculating the gravitational forces, a variant on the k-D tree, and a novel method for treating periodic boundary conditions.

[ascl:1102.007]
PixeLens: A Portable Modeler of Lensed Quasars

We introduce and implement two novel ideas for modeling lensed quasars. The first is to require different lenses to agree about H_{0}. This means that some models for one lens can be ruled out by data on a different lens. We explain using two worked examples. One example models 1115+080 and 1608+656 (time-delay quadruple systems) and 1933+503 (a prospective time-delay system) all together, yielding time-delay predictions for the third lens and a 90% confidence estimate of H_{0}^{-1}=14.6+9.4-1.7 Gyr (H_{0}=67+9-26 km s^{-1} Mpc^{-1}) assuming ΩM=0.3 and Ω_{Λ}=0.7. The other example models the time-delay doubles 1520+530, 1600+434, 1830-211, and 2149-275, which gives H_{0}^{-1}=14.5+3.3-1.5 Gyr (H_{0}=67+8-13 km s^{-1} Mpc^{-1}). Our second idea is to write the modeling software as a highly interactive Java applet, which can be used both for coarse-grained results inside a browser and for fine-grained results on a workstation. Several obstacles come up in trying to implement a numerically intensive method thus, but we overcome them.

[ascl:1405.012]
PISA: Position Intensity and Shape Analysis

PISA (Position, Intensity and Shape Analysis) routines deal with the location and parameterization of objects on an image frame. The core of this package is the routine PISAFIND which performs image analysis on a 2-dimensional data frame. The program searches the data array for objects that have a minimum number of connected pixels above a given threshold and extracts the image parameters (position, intensity, shape) for each object. The image parameters can be determined using thresholding techniques or an analytical stellar profile can be used to fit the objects. In crowded regions deblending of overlapping sources can be performed. PISA is distributed as part of the Starlink software collection (ascl:1110.012).

[ascl:1611.015]
Pippi: Parse and plot MCMC chains

Pippi (parse it, plot it) operates on MCMC chains and related lists of samples from a function or distribution, and can merge, parse, and plot sample ensembles ('chains') either in terms of the likelihood/fitness function directly, or as implied posterior probability densities. Pippi is compatible with ASCII text and hdf5 chains, operates out of core, and can post-process chains on the fly.

[ascl:1007.001]
PINTofALE: Package for Interactive Analysis of Line Emission

PINTofALE was originally developed to analyze spectroscopic data from optically-thin coronal plasmas, though much of the software is sufficiently general to be of use in a much wider range of astrophysical data analyses. It is based on a modular set of IDL tools that interact with an atomic database and with observational data. The tools are designed to allow easy identification of spectral features, measure line fluxes, and carry out detailed modeling. The basic philosophy of the package is to provide access to the innards of atomic line databases, and to have flexible tools to interactively compare with the observed data. It is motivated by the large amount of book-keeping, computation and iterative interaction that is required between the researcher and observational and theoretical data in order to derive astrophysical results. The tools link together transparently and automatically the processes of spectral "browsing", feature identification, measurement, and computation and derivation of results. Unlike standard modeling and fitting engines currently in use, PINTofALE opens up the "black box" of atomic data required for UV/X-ray analyses and allows the user full control over the data that are used in any given analysis.

[ascl:1902.007]
PINT: High-precision pulsar timing analysis package

Luo, Jing; Ransom, Scott; Demorest, Paul; van Haasteren, Rutger; Ray, Paul; Stovall, Kevin; Bachetti, Matteo; Archibald, Anne; Kerr, Matthew; Colen, Jonathan; Jenet, Fredrick

PINT (PINT Is Not Tempo3) analyzes high-precision pulsar timing data, enabling interactive data analysis and providing an extensible and flexible development platform for timing applications. PINT utilizes well-debugged public Python packages and modern software development practices (e.g., the NumPy and Astropy libraries, version control and development with git and GitHub, and various types of testing) for increased development efficiency and enhanced stability. PINT has been developed and implemented completely independently from traditional pulsar timing software such as TEMPO (ascl:1509.002) and Tempo2 (ascl:1210.015) and is a robust tool for cross-checking timing analyses and simulating data.

[ascl:1305.007]
PINOCCHIO: PINpointing Orbit-Crossing Collapsed HIerarchical Objects

PINOCCHIO generates catalogues of cosmological dark matter halos with known mass, position, velocity and merger history. It is able to reproduce, with very good accuracy, the hierarchical formation of dark matter halos from a realization of an initial (linear) density perturbation field, given on a 3D grid. Its setup is similar to that of a conventional N-body simulation, but it is based on the powerful Lagrangian Perturbation Theory. It runs in just a small fraction of the computing time taken by an equivalent N-body simulation, producing promptly the merging histories of all halos in the catalog.

[ascl:1407.012]
PINGSoft2: Integral Field Spectroscopy Software

PINGSoft2 visualizes, manipulates and analyzes integral field spectroscopy (IFS) data based on either 3D cubes or Raw Stacked Spectra (RSS) format. Any IFS data can be adapted to work with PINGSoft2, regardless of the original data format and the size/shape of the spaxel. Written in IDL, PINGSoft2 is optimized for fast visualization rendering; it also includes various routines useful for generic astronomy and spectroscopy tasks.

[ascl:1806.014]
pile-up: Monte Carlo simulations of star-disk torques on hot Jupiters

The pile-up gnuplot script generates a Monte Carlo simulation with a selectable number of randomized drawings (1000 by default, ~1min on a modern laptop). For each realization, the script calculates the torque acting on a hot Jupiter around a young, solar-type star as a function of the star-planet distance. The total torque on the planet is composed of the disk torque in the type II migration regime (that is, the planet is assumed to have opened up a gap in the disk) and of the stellar tidal torque. The model has four free parameters, which are drawn from a normal or lognormal distribution: (1) the disk's gas surface density at 1 astronomical unit, (2) the magnitude of tidal dissipation within the star, (3) the disk's alpha viscosity parameter, and (4) and the mean molecular weight of the gas in the disk midplane. For each realization, the total torque is screened for a distance at which it becomes zero. If present, then this distance would represent a tidal migration barrier to the planet. In other words, the planet would stop migrating. This location is added to a histogram on top of the main torque-over-distance panel and the realization is counted as one case that contributes to the overall survival rate of hot Jupiters. Finally, the script generates an output file (PDF by default) and prints the hot Jupiter survival rate for the assumed parameterization of the star-planet-disk system.

[ascl:1408.014]
pieflag: CASA task to efficiently flag bad data

pieflag compares bandpass-calibrated data to a clean reference channel and identifies and flags essentially all bad data. pieflag compares visibility amplitudes in each frequency channel to a 'reference' channel that is rfi-free (or manually ensured to be rfi-free). pieflag performs this comparison independently for each correlation on each baseline, but will flag all correlations if threshold conditions are met. To operate effectively, pieflag must be supplied with bandpass-calibrated data. pieflag has two core modes of operation (static and dynamic flagging) with an additional extend mode; the type of data largely determines which mode to choose. Instructions for pre-processing data and selecting the mode of operation are provided in the help file. Once pre-processing and selecting the mode of operation are done, pieflag should work well 'out of the box' with its default parameters.

[ascl:1607.009]
PICsar: Particle in cell pulsar magnetosphere simulator

PICsar simulates the magnetosphere of an aligned axisymmetric pulsar and can be used to simulate other arbitrary electromagnetics problems in axisymmetry. Written in Fortran, this special relativistic, electromagnetic, charge conservative particle in cell code features stretchable body-fitted coordinates that follow the surface of a sphere, simplifying the application of boundary conditions in the case of the aligned pulsar; a radiation absorbing outer boundary, which allows a steady state to be set up dynamically and maintained indefinitely from transient initial conditions; and algorithms for injection of charged particles into the simulation domain. PICsar is parallelized using MPI and has been used on research problems with ~1000 CPUs.

[ascl:1306.011]
Pico: Parameters for the Impatient Cosmologist

Pico is an algorithm that quickly computes the CMB scalar, tensor and lensed power spectra, the matter transfer function and the WMAP 5 year likelihood. It is intended to accelerate parameter estimation codes; Pico can compute the CMB power spectrum and matter transfer function, as well as any computationally expensive likelihoods, in a few milliseconds. It is extremely fast and accurate over a large volume of parameter space and its accuracy can be improved by using a larger training set. More generally, Pico allows using massively parallel computing resources, including distributed computing projects such as Cosmology@Home, to speed up the slow steps in inherently sequential calculations.

[ascl:1610.001]
Piccard: Pulsar timing data analysis package

Piccard is a Bayesian-inference pipeline for Pulsar Timing Array (PTA) data and interacts with Tempo2 (ascl:1210.015) through libstempo. The code is used mainly for single-pulsar analysis and gravitational-wave detection purposes of full Pulsar Timing Array datasets. Modeling of the data can include correlated signals per frequency or modeled spectrum, with uniform, dipolar, quadrupolar, or anisotropic correlations; multiple error bars and EFACs per pulsar; and white and red noise. Timing models can be numerically included, either by using the design matrix (linear timing model), or by calling libstempo for the full non-linear timing model. Many types of samplers are included. For common-mode mitigation, the signals can be reconstructed mitigating arbitrary signals simultaneously.

[ascl:1905.019]
PICASO: Planetary Intensity Code for Atmospheric Scattering Observations

PICASO (Planetary Intensity Code for Atmospheric Scattering Observations), written in Python, computes the reflected light of exoplanets at any phase geometry using direct and diffuse scattering phase functions and Raman scattering spectral features.

[ascl:1412.007]
PIAO: Python spherIcAl Overdensity code

PIAO is an efficient memory-controlled Python code that uses the standard spherical overdensity (SO) algorithm to identify halos. PIAO employs two additional parameters besides the overdensity Δc. The first is the mesh-box size, which splits the whole simulation box into smaller ones then analyzes them one-by-one, thereby overcoming a possible memory limitation problem that can occur when dealing with high-resolution, large-volume simulations. The second is the smoothed particle hydrodynamics (SPH) neighbors number, which is used for the SPH density calculation.

[ascl:1408.003]
PIA: ISOPHOT Interactive Analysis

Gabriel, Carlos; Acosta, Jose; Heinrichsen, Ingolf; Skaley, Detlef; Tai, Wai Ming; Morris, Huw; Merluzzi, Paola

ISOPHOT is one of the instruments on board the Infrared Space Observatory (ISO). ISOPHOT Interactive Analysis (PIA) is a scientific and calibration interactive data analysis tool for ISOPHOT data reduction. Written in IDL under Xwindows, PIA offers a full context sensitive graphical interface for retrieving, accessing and analyzing ISOPHOT data. It is available in two nearly identical versions; a general observers version omits the calibration sequences.

[ascl:1112.004]
PHOX: X-ray Photon Simulator

PHOX is a novel, virtual X-ray observatory designed to obtain synthetic observations from hydro-numerical simulations. The code is a photon simulator and can be apply to simulate galaxy clusters. In fact, X-ray observations of clusters of galaxies continue to provide us with an increasingly detailed picture of their structure and of the underlying physical phenomena governing the gaseous component, which dominates their baryonic content. Therefore, it is fundamental to find the most direct and faithful way to compare such observational data with hydrodynamical simulations of cluster-like objects, which can currently include various complex physical processes. Here, we present and analyse synthetic Suzaku observations of two cluster-size haloes obtained by processing with PHOX the hydrodynamical simulation of the large-scale, filament-like region in which they reside. Taking advantage of the simulated data, we test the results inferred from the X-ray analysis of the mock observations against the underlying, known solution. Remarkably, we are able to recover the theoretical temperature distribution of the two haloes by means of the multi-temperature fitting of the synthetic spectra. Moreover, the shapes of the reconstructed distributions allow us to trace the different thermal structure that distinguishes the dynamical state of the two haloes.

[ascl:1609.011]
Photutils: Photometry tools

Bradley, Larry; Sipocz, Brigitta; Robitaille, Thomas; Tollerud, Erik; Deil, Christoph; Vinícius, Zè; Barbary, Kyle; Günther, Hans Moritz; Bostroem, Azalee; Droettboom, Michael; Bray, Erik; Bratholm, Lars Andersen; Pickering, T. E.; Craig, Matt; Pascual, Sergio; Greco, Johnny; Donath, Axel; Kerzendorf, Wolfgang; Littlefair, Stuart; Barentsen, Geert; D'Eugenio, Francesco; Weaver, Benjamin Alan

Photutils provides tools for detecting and performing photometry of astronomical sources. It can estimate the background and background rms in astronomical images, detect sources in astronomical images, estimate morphological parameters of those sources (e.g., centroid and shape parameters), and perform aperture and PSF photometry. Written in Python, it is an affiliated package of Astropy (ascl:1304.002).

[ascl:1408.022]
PhotoRApToR: PHOTOmetric Research APplication TO Redshifts

PhotoRApToR (PHOTOmetric Research APplication TO Redshifts) solves regression and classification problems and is specialized for photo-z estimation. PhotoRApToR offers data table manipulation capabilities and 2D and 3D graphics tools for data visualization; it also provides a statistical report for both classification and regression experiments. The code is written in Java; the machine learning model is in C++ to increase the core execution speed.

[ascl:1901.007]
Photon: Python tool for data plotting

Photon makes simple 1D plots in python. It uses mainly matplotlib and PyQt5 and has been build to be fully customizable, allowing the user to change the fontstyle, fontsize, fontcolors, linewidth of the axes, thickness, and other parameters, and see the changes directly in the plot. Once a customization is created, it can be saved in a configuration file and reloaded for future use, allowing reuse of the customization for other plots. The main tool is a graphical user interface and it is started using a command line interface.

[ascl:1703.004]
PHOTOMETRYPIPELINE: Automated photometry pipeline

PHOTOMETRYPIPELINE (PP) provides calibrated photometry from imaging data obtained with small to medium-sized observatories. PP uses Source Extractor (ascl:1010.064) and SCAMP (ascl:1010.063) to register the image data and perform aperture photometry. Calibration is obtained through matching of field stars with reliable photometric catalogs. PP has been specifically designed for the measurement of asteroid photometry, but can also be used to obtain photometry of fixed sources.

[ascl:1405.013]
PHOTOM: Photometry of digitized images

Eaton, Nicholas; Draper, Peter W.; Allan, Alasdair; Naylor, Tim; Mukai, Koji; Currie, Malcolm J.; McCaughrean, Mark

PHOTOM performs photometry of digitized images. It has two basic modes of operation: using an interactive display to specify the positions for the measurements, or obtaining those positions from a file. In both modes of operation PHOTOM performs photometry using either the traditional aperture method or via optimal extraction. When using the traditional aperture extraction method the target aperture can be circular or elliptical and its size and shape can be varied interactively on the display, or by entering values from the keyboard. Both methods allow the background sky level to be either sampled interactively by the manual positioning of an aperture, or automatically from an annulus surrounding the target object. PHOTOM is the photometry backend for the GAIA tool (ascl:1403.024) and is part of the Starlink software collection (ascl:1110.012).

[ascl:1712.013]
photodynam: Photodynamical code for fitting the light curves of multiple body systems

Photodynam facilitates so-called "photometric-dynamical" modeling. This model is quite simple and this is reflected in the code base. A N-body code provides coordinates and the photometric code produces light curves based on coordinates.

[ascl:1704.009]
Photo-z-SQL: Photometric redshift estimation framework

Photo-z-SQL is a flexible template-based photometric redshift estimation framework that can be seamlessly integrated into a SQL database (or DB) server and executed on demand in SQL. The DB integration eliminates the need to move large photometric datasets outside a database for redshift estimation, and uses the computational capabilities of DB hardware. Photo-z-SQL performs both maximum likelihood and Bayesian estimation and handles inputs of variable photometric filter sets and corresponding broad-band magnitudes.

[ascl:1307.011]
PhoSim: Photon Simulator

The Photon Simulator (PhoSim) is a set of fast photon Monte Carlo codes used to calculate the physics of the atmosphere, telescope, and detector by using modern numerical techniques applied to comprehensive physical models. PhoSim generates images by collecting photons into pixels. The code takes the description of what astronomical objects are in the sky at a particular time (the instance catalog) as well as the description of the observing configuration (the operational parameters) and produces a realistic data stream of images that are similar to what a real telescope would produce. PhoSim was developed for large aperture wide field optical telescopes, such as the planned design of LSST. The initial version of the simulator also targeted the LSST telescope and camera design, but the code has since been broadened to include existing telescopes of a related nature. The atmospheric model, in particular, includes physical approximations that are limited to this general context.

[ascl:1010.056]
PHOENIX: A General-purpose State-of-the-art Stellar and Planetary Atmosphere Code

PHOENIX is a general-purpose state-of-the-art stellar and planetary atmosphere code. It can calculate atmospheres and spectra of stars all across the HR-diagram including main sequence stars, giants, white dwarfs, stars with winds, TTauri stars, novae, supernovae, brown dwarfs and extrasolar giant planets.

[ascl:1106.002]
PHOEBE: PHysics Of Eclipsing BinariEs

PHOEBE (PHysics Of Eclipsing BinariEs) is a modeling package for eclipsing binary stars, built on top of the widely used WD program (Wilson & Devinney 1971). This introductory paper overviews most important scientific extensions (incorporating observational spectra of eclipsing binaries into the solution-seeking process, extracting individual temperatures from observed color indices, main-sequence constraining and proper treatment of the reddening), numerical innovations (suggested improvements to WD's Differential Corrections method, the new Nelder & Mead's downhill Simplex method) and technical aspects (back-end scripter structure, graphical user interface). While PHOEBE retains 100% WD compatibility, its add-ons are a powerful way to enhance WD by encompassing even more physics and solution reliability.

[ascl:1112.006]
PhAst: Display and Analysis of FITS Images

PhAst (Photometry-Astrometry) is an IDL astronomical image viewer based on the existing application ATV which displays and analyzes FITS images. It can calibrate raw images, provide astrometric solutions, and do circular aperture photometry. PhAst allows the user to load, process, and blink any number of images. Analysis packages include image calibration, photometry, and astrometry (provided through an interface with SExtractor, SCAMP, and missFITS). PhAst has been designed to generate reports for Minor Planet Center reporting.

[ascl:1611.019]
phase_space_cosmo_fisher: Fisher matrix 2D contours

phase_space_cosmo_fisher produces Fisher matrix 2D contours from which the constraints on cosmological parameters can be derived. Given a specified redshift array and cosmological case, 2D marginalized contours of cosmological parameters are generated; the code can also plot the derivatives used in the Fisher matrix. In addition, this package can generate 3D plots of qH^2 and other cosmological quantities as a function of redshift and cosmology.

[ascl:1709.002]
PHANTOM: Smoothed particle hydrodynamics and magnetohydrodynamics code

Price, Daniel J.; Wurster, James; Nixon, Chris; Tricco, Terrence S.; Toupin, Stéven; Pettitt, Alex; Chan, Conrad; Laibe, Guillaume; Glover, Simon; Dobbs, Clare; Nealon, Rebecca; Liptai, David; Worpel, Hauke; Bonnerot, Clément; Dipierro, Giovanni; Ragusa, Enrico; Federrath, Christoph; Iaconi, Roberto; Reichardt, Thomas; Forgan, Duncan; Hutchison, Mark; Constantino, Thomas; Ayliffe, Ben; Mentiplay, Daniel; Hirsh, Kieran; Lodato, Giuseppe

Phantom is a smoothed particle hydrodynamics and magnetohydrodynamics code focused on stellar, galactic, planetary, and high energy astrophysics. It is modular, and handles sink particles, self-gravity, two fluid and one fluid dust, ISM chemistry and cooling, physical viscosity, non-ideal MHD, and more. Its modular structure makes it easy to add new physics to the code.

[ascl:1209.008]
Phantom-GRAPE: SIMD accelerated numerical library for N-body simulations

Phantom-GRAPE is a numerical software library to accelerate collisionless $N$-body simulation with SIMD instruction set on x86 architecture. The Newton's forces and also central forces with an arbitrary shape f(r), which have a finite cutoff radius r_cut (i.e. f(r)=0 at r>r_cut), can be quickly computed.

[ascl:1103.002]
PGPLOT: Device-independent Graphics Package for Simple Scientific Graphs

The PGPLOT Graphics Subroutine Library is a Fortran- or C-callable, device-independent graphics package for making simple scientific graphs. It is intended for making graphical images of publication quality with minimum effort on the part of the user. For most applications, the program can be device-independent, and the output can be directed to the appropriate device at run time.

The PGPLOT library consists of two major parts: a device-independent part and a set of device-dependent "device handler" subroutines for output on various terminals, image displays, dot-matrix printers, laser printers, and pen plotters. Common file formats supported include PostScript and GIF.

PGPLOT itself is written mostly in standard Fortran-77, with a few non-standard, system-dependent subroutines. PGPLOT subroutines can be called directly from a Fortran-77 or Fortran-90 program. A C binding library (cpgplot) and header file (cpgplot.h) are provided that allow PGPLOT to be called from a C or C++ program; the binding library handles conversion between C and Fortran argument-passing conventions.

[ascl:1812.003]
PFANT: Stellar spectral synthesis code

PFANT computes a synthetic spectrum assuming local thermodynamic equilibrium from a given stellar model atmosphere and lists of atomic and molecular lines; it provides large wavelength coverage and line lists from ultraviolet through the visible and near-infrared. PFANT has been optimized for speed, offers error reporting, and command-line configuration options.

[ascl:1407.009]
Period04: Statistical analysis of large astronomical time series

Period04 statistically analyzes large astronomical time series containing gaps. It calculates formal uncertainties, can extract the individual frequencies from the multiperiodic content of time series, and provides a flexible interface to perform multiple-frequency fits with a combination of least-squares fitting and the discrete Fourier transform algorithm. Period04, written in Java/C++, supports the SAMP communication protocol to provide interoperability with other applications of the Virtual Observatory. It is a reworked and extended version of Period98 (Sperl 1998) and PERIOD/PERDET (Breger 1990).

[ascl:1406.005]
PERIOD: Time-series analysis package

PERIOD searches for periodicities in data. It is distributed within the Starlink software collection (ascl:1110.012).

[ascl:1809.005]
perfectns: "Perfect" dynamic and standard nested sampling for spherically symmetric likelihoods and priors

perfectns performs dynamic nested sampling and standard nested sampling for spherically symmetric likelihoods and priors, and analyses the samples produced. The spherical symmetry allows the nested sampling algorithm to be followed “perfectly” - *i.e.* without implementation-specific errors correlations between samples. It is intended for use in research into the statistical properties of nested sampling, and to provide a benchmark for testing the performance of nested sampling software packages used for practical problems - which rely on numerical techniques to produce approximately uncorrelated samples.

[ascl:1811.019]
PENTACLE: Large-scale particle simulations code for planet formation

PENTACLE calculates gravitational interactions between particles within a cut-off radius and a Barnes-Hut tree method for gravity from particles beyond. It uses FDPS (ascl:1604.011) to parallelize a Barnes-Hut tree algorithm for a memory-distributed supercomputer. The software can handle 1-10 million particles in a high-resolution N-body simulation on CPU clusters for collisional dynamics, including physical collisions in a planetesimal disc.

[ascl:1010.060]
Pencil: Finite-difference Code for Compressible Hydrodynamic Flows

The Pencil code is a high-order finite-difference code for compressible hydrodynamic flows with magnetic fields. It is highly modular and can easily be adapted to different types of problems. The code runs efficiently under MPI on massively parallel shared- or distributed-memory computers, like e.g. large Beowulf clusters. The Pencil code is primarily designed to deal with weakly compressible turbulent flows. To achieve good parallelization, explicit (as opposed to compact) finite differences are used. Typical scientific targets include driven MHD turbulence in a periodic box, convection in a slab with non-periodic upper and lower boundaries, a convective star embedded in a fully nonperiodic box, accretion disc turbulence in the shearing sheet approximation, self-gravity, non-local radiation transfer, dust particle evolution with feedback on the gas, etc. A range of artificial viscosity and diffusion schemes can be invoked to deal with supersonic flows. For direct simulations regular viscosity and diffusion is being used. The code is written in well-commented Fortran90.

[ascl:1507.003]
Pelican: Pipeline for Extensible, Lightweight Imaging and CAlibratioN

Pelican is an efficient, lightweight C++ library for quasi-real time data processing. The library provides a framework to separate the acquisition and processing of data, allowing the scalability and flexibility to fit a number of scenarios. Though its origin was in radio astronomy, processing data as it arrives from a telescope, the framework is sufficiently generic to be useful to any application that requires the efficient processing of incoming data streams.

[ascl:1108.007]
PÉGASE: Metallicity-consistent Spectral Evolution Model of Galaxies

PÉGASE (Projet d'Étude des GAlaxies par Synthèse Évolutive) is a code to compute the spectral evolution of galaxies. The evolution of the stars, gas and metals is followed for a law of star formation and a stellar initial mass function. The stellar evolutionary tracks extend from the main sequence to the white dwarf stage. The emission of the gas in HII regions is also taken into account. The main improvement in version 2 is the use of evolutionary tracks of different metallicities (from 10-4 to 5×solar). The effect of extinction by dust is also modelled using a radiative transfer code. PÉGASE.2 uses the BaSeL library of stellar spectra and can therefore synthesize low-resolution (R~200) ultraviolet to near-infrared spectra of Hubble sequence galaxies as well as of starbursts.

[ascl:1108.008]
PÉGASE-HR: Stellar Population Synthesis at High Resolution Spectra

Le Borgne, Damien; Fioc, Michel; Lançon, Ariane; Rocca-Volmerange, Brigitte; Prugniel, Philippe; Soubiran, Caroline

PÉGASE-HR is a code aimed at computing synthetic evolutive optical spectra of galaxies with a very high resolution (R=10 000, or dlambda=0.55) in the range Lambda=[4000, 6800] Angstroms. PÉGASE-HR is the result of combining the code PÉGASE.2 with the high-resolution stellar library ÉLODIE. This code can also be used at low resolution (R=200) over the range covered by the BaSeL library (from far UV to the near IR), and then produces the same results as PÉGASE.2. In PEGASE-HR, the BaSeL library is replaced by a grid of spectra interpolated from the high-resolution ÉLODIE library of stellar spectra. The ÉLODIE library is a stellar database of 1959 spectra for 1503 stars, observed with the echelle spectrograph ÉLODIE on the 193 cm telescope at the Observatoire de Haute Provence.

[ascl:1304.001]
PEC: Period Error Calculator

The PEC (Period Error Calculator) algorithm estimates the period error for eclipsing binaries observed by the Kepler Mission. The algorithm is based on propagation of error theory and assumes that observation of every light curve peak/minimum in a long time-series observation can be unambiguously identified. A simple C implementation of the PEC algorithm is available.

[ascl:1605.008]
PDT: Photometric DeTrending Algorithm Using Machine Learning

PDT removes systematic trends in light curves. It finds clusters of light curves that are highly correlated using machine learning, constructs one master trend per cluster and detrends an individual light curve using the constructed master trends by minimizing residuals while constraining coefficients to be positive.

[ascl:1102.022]
PDRT: Photo Dissociation Region Toolbox

Ultraviolet photons from O and B stars strongly influence the structure and emission spectra of the interstellar medium. The UV photons energetic enough to ionize hydrogen (hν > 13.6 eV) will create the H II region around the star, but lower energy UV photons escape. These far-UV photons (6 eV < hν < 13.6 eV) are still energetic enough to photodissociate molecules and to ionize low ionization-potential atoms such as carbon, silicon, and sulfur. They thus create a photodissociation region (PDR) just outside the H II region. In aggregate, these PDRs dominates the heating and cooling of the neutral interstellar medium.

As part of the Web Infrared Tool Shed (WITS) we have developed a web tool, called the PDR Toolbox, that allows users to determine the physical parameters of a PDR from a set of spectral line observations. Typical observations of both Galactic and extragalactic PDRs come from ground-based millimeter and submillimeter telescopes such as CARMA or the CSO, or space-based telescopes such as Spitzer, ISO, SOFIA, and Herschel. Given a set of observations of spectral line intensities, PDR Toolbox will compute best-fit FUV incident intensity and cloud density based on our published models of PDR emission.

[ascl:1809.002]
PCCDPACK: Polarimetry with CCD

PCCDPACK analyzes polarimetry data. The set of routines is written in CL-IRAF (including compiled Fortran codes) and analyzes dozens of point objects simultaneously on the same CCD image. A subpackage, specpol, is included to analyze spectropolarimetry data.

[ascl:1705.004]
PCAT: Probabilistic Cataloger

PCAT (Probabilistic Cataloger) samples from the posterior distribution of a metamodel, i.e., union of models with different dimensionality, to compare the models. This is achieved via transdimensional proposals such as births, deaths, splits and merges in addition to the within-model proposals. This method avoids noisy estimates of the Bayesian evidence that may not reliably distinguish models when sampling from the posterior probability distribution of each model.

The code has been applied in two different subfields of astronomy: high energy photometry, where transdimensional elements are gamma-ray point sources; and strong lensing, where light-deflecting dark matter subhalos take the role of transdimensional elements.

[ascl:1207.012]
PCA: Principal Component Analysis for spectra modeling

The mid-infrared spectra of ultraluminous infrared galaxies (ULIRGs) contain a variety of spectral features that can be used as diagnostics to characterize the spectra. However, such diagnostics are biased by our prior prejudices on the origin of the features. Moreover, by using only part of the spectrum they do not utilize the full information content of the spectra. Blind statistical techniques such as principal component analysis (PCA) consider the whole spectrum, find correlated features and separate them out into distinct components.

This code, written in IDL, classifies principal components of IRS spectra to define a new classification scheme using 5D Gaussian mixtures modelling. The five PCs and average spectra for the four classifications to classify objects are made available with the code.

[ascl:1708.007]
PBMC: Pre-conditioned Backward Monte Carlo code for radiative transport in planetary atmospheres

PBMC (Pre-Conditioned Backward Monte Carlo) solves the vector Radiative Transport Equation (vRTE) and can be applied to planetary atmospheres irradiated from above. The code builds the solution by simulating the photon trajectories from the detector towards the radiation source, *i.e.* in the reverse order of the actual photon displacements. In accounting for the polarization in the sampling of photon propagation directions and pre-conditioning the scattering matrix with information from the scattering matrices of prior (in the BMC integration order) photon collisions, PBMC avoids the unstable and biased solutions of classical BMC algorithms for conservative, optically-thick, strongly-polarizing media such as Rayleigh atmospheres.

[ascl:1102.002]
PBL: Particle-Based Lensing for Gravitational Lensing Mass Reconstructions of Galaxy Clusters

We present Particle-Based Lensing (PBL), a new technique for gravitational lensing mass reconstructions of galaxy clusters. Traditionally, most methods have employed either a finite inversion or gridding to turn observational lensed galaxy ellipticities into an estimate of the surface mass density of a galaxy cluster. We approach the problem from a different perspective, motivated by the success of multi-scale analysis in smoothed particle hydrodynamics. In PBL, we treat each of the lensed galaxies as a particle and then reconstruct the potential by smoothing over a local kernel with variable smoothing scale. In this way, we can tune a reconstruction to produce constant signal-noise throughout, and maximally exploit regions of high information density.

PBL is designed to include all lensing observables, including multiple image positions and fluxes from strong lensing, as well as weak lensing signals including shear and flexion. In this paper, however, we describe a shear-only reconstruction, and apply the method to several test cases, including simulated lensing clusters, as well as the well-studied ``Bullet Cluster'' (1E0657-56). In the former cases, we show that PBL is better able to identify cusps and substructures than are grid-based reconstructions, and in the latter case, we show that PBL is able to identify substructure in the Bullet Cluster without even exploiting strong lensing measurements.

[ascl:1809.003]
PASTA: Python Astronomical Stacking Tool Array

PASTA performs median stacking of astronomical sources. Written in Python, it can filter sources, provide stack statistics, generate Karma annotations, format source lists, and read information from stacked Flexible Image Transport System (FITS) images. PASTA was originally written to examine polarization stack properties and includes a Monte Carlo modeler for obtaining true polarized intensity from the observed polarization of a stack. PASTA is also useful as a generic stacking tool, even if polarization properties are not being examined.

[ascl:1010.073]
partiview: Immersive 4D Interactive Visualization of Large-Scale Simulations

In dense clusters a bewildering variety of interactions between stars can be observed, ranging from simple encounters to collisions and other mass-transfer encounters. With faster and special-purpose computers like GRAPE, the amount of data per simulation is now exceeding 1TB. Visualization of such data has now become a complex 4D data-mining problem, combining space and time, and finding interesting events in these large datasets. We have recently starting using the virtual reality simulator, installed in the Hayden Planetarium in the American Museum for Natural History, to tackle some of these problem. partiview is a program that enables you to visualize and animate particle data. partiview runs on relatively simple desktops and laptops, but is mostly compatible with its big brother VirDir.

[ascl:1010.005]
Particle module of Piernik MHD code

Piernik is a multi-fluid grid magnetohydrodynamic (MHD) code based on the Relaxing Total Variation Diminishing (RTVD) conservative scheme. The original code has been extended by addition of dust described within the particle approximation. The dust is now described as a system of interacting particles. The particles can interact with gas, which is described as a fluid. The comparison between the test problem results and the results coming from fluid simulations made with Piernik code shows the most important differences between fluid and particle approximations used to describe dynamical evolution of dust under astrophysical conditions.

[ascl:1208.020]
ParselTongue: AIPS Python Interface

ParselTongue is a Python interface to classic AIPS, Obit and possibly other task-based data reduction packages. It serves as the software infrastructure for some of the ALBUS implementation. It allows you to run AIPS tasks, and access AIPS headers and extension tables from Python. There is also support for running Obit tasks and accessing data in FITS files. Full access to the visibilities in AIPS UV data is also available.

[ascl:1502.005]
PARSEC: PARametrized Simulation Engine for Cosmic rays

PARSEC (PARametrized Simulation Engine for Cosmic rays) is a simulation engine for fast generation of ultra-high energy cosmic ray data based on parameterizations of common assumptions of UHECR origin and propagation. Implemented are deflections in unstructured turbulent extragalactic fields, energy losses for protons due to photo-pion production and electron-pair production, as well as effects from the expansion of the universe. Additionally, a simple model to estimate propagation effects from iron nuclei is included. Deflections in the Galactic magnetic field are included using a matrix approach with precalculated lenses generated from backtracked cosmic rays. The PARSEC program is based on object oriented programming paradigms enabling users to extend the implemented models and is steerable with a graphical user interface.

[ascl:1601.010]
PARAVT: Parallel Voronoi Tessellation

PARAVT offers massive parallel computation of Voronoi tessellations (VT hereafter) in large data sets. The code is focused for astrophysical purposes where VT densities and neighbors are widely used. There are several serial Voronoi tessellation codes, however no open source and parallel implementations are available to handle the large number of particles/galaxies in current N-body simulations and sky surveys. Parallelization is implemented under MPI and VT using Qhull library. Domain decomposition take into account consistent boundary computation between tasks, and support periodic conditions. In addition, the code compute neighbors lists, Voronoi density and Voronoi cell volumes for each particle, and can compute density on a regular grid.

[ascl:1103.014]
ParaView: Data Analysis and Visualization Application

ParaView is an open-source, multi-platform data analysis and visualization application. ParaView users can quickly build visualizations to analyze their data using qualitative and quantitative techniques. The data exploration can be done interactively in 3D or programmatically using ParaView's batch processing capabilities.

ParaView was developed to analyze extremely large datasets using distributed memory computing resources. It can be run on supercomputers to analyze datasets of terascale as well as on laptops for smaller data.

[ascl:1010.039]
Parameter Estimation from Time-Series Data with Correlated Errors: A Wavelet-Based Method and its Application to Transit Light Curves

We consider the problem of fitting a parametric model to time-series data that are afflicted by correlated noise. The noise is represented by a sum of two stationary Gaussian processes: one that is uncorrelated in time, and another that has a power spectral density varying as $1/f^gamma$. We present an accurate and fast [O(N)] algorithm for parameter estimation based on computing the likelihood in a wavelet basis. The method is illustrated and tested using simulated time-series photometry of exoplanetary transits, with particular attention to estimating the midtransit time. We compare our method to two other methods that have been used in the literature, the time-averaging method and the residual-permutation method. For noise processes that obey our assumptions, the algorithm presented here gives more accurate results for midtransit times and truer estimates of their uncertainties.

[ascl:1106.009]
PARAMESH V4.1: Parallel Adaptive Mesh Refinement

PARAMESH is a package of Fortran 90 subroutines designed to provide an application developer with an easy route to extend an existing serial code which uses a logically cartesian structured mesh into a parallel code with adaptive mesh refinement (AMR). Alternatively, in its simplest use, and with minimal effort, it can operate as a domain decomposition tool for users who want to parallelize their serial codes, but who do not wish to use adaptivity.

The package builds a hierarchy of sub-grids to cover the computational domain, with spatial resolution varying to satisfy the demands of the application. These sub-grid blocks form the nodes of a tree data-structure (quad-tree in 2D or oct-tree in 3D). Each grid block has a logically cartesian mesh. The package supports 1, 2 and 3D models. PARAMESH is released under the NASA-wide Open-Source software license.

[ascl:1103.008]
Parallel HOP: A Scalable Halo Finder for Massive Cosmological Data Sets

Modern N-body cosmological simulations contain billions ($10^9$) of dark matter particles. These simulations require hundreds to thousands of gigabytes of memory, and employ hundreds to tens of thousands of processing cores on many compute nodes. In order to study the distribution of dark matter in a cosmological simulation, the dark matter halos must be identified using a halo finder, which establishes the halo membership of every particle in the simulation. The resources required for halo finding are similar to the requirements for the simulation itself. In particular, simulations have become too extensive to use commonly-employed halo finders, such that the computational requirements to identify halos must now be spread across multiple nodes and cores. Here we present a scalable-parallel halo finding method called Parallel HOP for large-scale cosmological simulation data. Based on the halo finder HOP, it utilizes MPI and domain decomposition to distribute the halo finding workload across multiple compute nodes, enabling analysis of much larger datasets than is possible with the strictly serial or previous parallel implementations of HOP. We provide a reference implementation of this method as a part of the toolkit yt, an analysis toolkit for Adaptive Mesh Refinement (AMR) data that includes complementary analysis modules. Additionally, we discuss a suite of benchmarks that demonstrate that this method scales well up to several hundred tasks and datasets in excess of $2000^3$ particles. The Parallel HOP method and our implementation can be readily applied to any kind of N-body simulation data and is therefore widely applicable. Parallel HOP is part of yt.

[ascl:1511.009]
Pangloss: Reconstructing lensing mass

Pangloss reconstructs all the mass within a light cone through the Universe. Understanding complex mass distributions like this is important for accurate time delay lens cosmography, and also for accurate lens magnification estimation. It aspires to use all available data in an attempt to make the best of all mass maps.

[ascl:1906.016]
PandExo: Instrument simulations for exoplanet observation planning

Batalha, Natasha E.; Mandell, Avi; Pontoppidan, Klaus; Stevenson, Kevin B.; Lewis, Nikole K.; Kalirai, Jason; Earl, Nick; Greene, Thomas; Albert, Loïc; Nielsen, Louise D.

PandExo generates instrument simulations of JWST’s NIRSpec, NIRCam, NIRISS and NIRCam and HST WFC3 for planning exoplanet observations. It uses throughput calculations from STScI’s Exposure Time Calculator, Pandeia, and offers both an online tool and a python package.

[ascl:1805.021]
PampelMuse: Crowded-field 3D spectroscopy

PampelMuse analyzes integral-field spectroscopic observations of crowded stellar fields and provides several subroutines to perform the individual steps of the data analysis. All analysis steps assume that the IFS data has been properly reduced and that all the instrumental artifacts have been removed. PampelMuse is designed to correctly handle IFS data regardless of which instrument was used to observe the data. In addition to the actual data, the software also requires an estimate of the variances for the analysis; optionally, it can use a bad pixel mask. The analysis relies on the presence of a reference catalogue, containing coordinates and magnitudes of the stars in and around the observed field.

[ascl:1406.002]
PAMELA: Optimal extraction code for long-slit CCD spectroscopy

PAMELA is an implementation of the optimal extraction algorithm for long-slit CCD spectroscopy and is well suited for time-series spectroscopy. It properly implements the optimal extraction algorithm for curved spectra, including on-the-fly cosmic ray rejection as well as proper calculation and propagation of the errors. The software is distributed as part of the Starlink software collection (ascl:1110.012).

[ascl:1606.002]
PAL: Positional Astronomy Library

The PAL library is a partial re-implementation of Pat Wallace's popular SLALIB library written in C using a Gnu GPL license and layered on top of the IAU's SOFA library (or the BSD-licensed ERFA) where appropriate. PAL attempts to stick to the SLA C API where possible.

[ascl:1210.009]
PAHFIT: Properties of PAH Emission

PAHFIT is an IDL tool for decomposing Spitzer IRS spectra of PAH emission sources, with a special emphasis on the careful recovery of ambiguous silicate absorption, and weak, blended dust emission features. PAHFIT is primarily designed for use with full 5-35 micron Spitzer low-resolution IRS spectra. PAHFIT is a flexible tool for fitting spectra, and you can add or disable features, compute combined flux bands, change fitting limits, etc., without changing the code.

PAHFIT uses a simple, physically-motivated model, consisting of starlight, thermal dust continuum in a small number of fixed temperature bins, resolved dust features and feature blends, prominent emission lines (which themselves can be blended with dust features), as well as simple fully-mixed or screen dust extinction, dominated by the silicate absorption bands at 9.7 and 18 microns. Most model components are held fixed or are tightly constrained. PAHFIT uses Drude profiles to recover the full strength of dust emission features and blends, including the significant power in the wings of the broad emission profiles. This means the resulting feature strengths are larger (by factors of 2-4) than are recovered by methods which estimate the underlying continuum using line segments or spline curves fit through fiducial wavelength anchors.

[ascl:1708.014]
PACSman: IDL Suite for Herschel/PACS spectrometer data

PACSman provides an alternative for several reduction and analysis steps performed in HIPE (ascl:1111.001) on PACS spectroscopic data; it is written in IDL. Among the operations possible with it are transient correction, line fitting, map projection, and map analysis, and unchopped scan, chop/nod, and the decommissioned wavelength switching observation modes are supported.

[ascl:1110.011]
Pacerman: Polarisation Angle CorrEcting Rotation Measure ANalysis

Pacerman, written in IDL, is a new method to calculate Faraday rotation measure maps from multi-frequency polarisation angle data. In order to solve the so called n-pi-ambiguity problem which arises from the observationally ambiguity of the polarisation angle which is only determined up to additions of n times pi, where n is an integer, we suggest using a global scheme. Instead of solving the n-pi-ambiguity for each data point independently, our algorithm, which we chose to call Pacerman solves the n-pi-ambiguity for a high signal-to-noise region "democratically" and uses this information to assist computations in adjacent low signal-to-noise areas.

[ascl:1105.002]
PACCE: Perl Algorithm to Compute Continuum and Equivalent Widths

PACCE (Perl Algorithm to Compute continuum and Equivalent Widths) computes continuum and equivalent widths. PACCE is able to determine mean continuum and continuum at line center values, which are helpful in stellar population studies, and is also able to compute the uncertainties in the equivalent widths using photon statistics.

[ascl:1205.002]
p3d: General data-reduction tool for fiber-fed integral-field spectrographs

p3d is semi-automatic data-reduction tool designed to be used with fiber-fed integral-field spectrographs. p3d is a highly general and freely available tool based on IDL but can be used with full functionality without an IDL license. It is easily extended to include improved algorithms, new visualization tools, and support for additional instruments. It uses a novel algorithm for automatic finding and tracing of spectra on the detector, and includes two methods of optimal spectrum extraction in addition to standard aperture extraction. p3d also provides tools to combine several images, perform wavelength calibration and flat field data.

[ascl:1402.030]
P2SAD: Particle Phase Space Average Density

P2SAD computes the Particle Phase Space Average Density (P2SAD) in galactic haloes. The model for the calculation is based on the stable clustering hypothesis in phase space, the spherical collapse model, and tidal disruption of substructures. The multiscale prediction for P2SAD computed by this IDL code can be used to estimate signals sensitive to the small scale structure of dark matter distributions (e.g. dark matter annihilation). The code computes P2SAD averaged over the whole virialized region of a Milky-Way-size halo at redshift zero.

[ascl:1806.011]
P2DFFT: Parallelized technique for measuring galactic spiral arm pitch angles

P2DFFT is a parallelized version of 2DFFT (ascl:1608.015). It isolates and measures the spiral arm pitch angle of galaxies. The code allows direct input of FITS images, offers the option to output inverse Fourier transform FITS images, and generates idealized logarithmic spiral test images of a specified size that have 1 to 6 arms with pitch angles of -75 degrees to 75 degrees. Further, it can output Fourier amplitude versus inner radius and pitch angle versus inner radius for each Fourier component (m = 0 to m = 6), and calculates the Fourier amplitude weighted mean pitch angle across m = 1 to m = 6 versus inner radius.

[ascl:1611.011]
OXAF: Ionizing spectra of Seyfert galaxies for photoionization modeling

Thomas, Adam D.; Groves, Brent A.; Sutherland, Ralph S.; Dopita, Michael A.; Jin, Chichuan; Kewley, Lisa J.

OXAF provides a simplified model of Seyfert Active Galactic Nucleus (AGN) continuum emission designed for photoionization modeling. It removes degeneracies in the effects of AGN parameters on model spectral shapes and reproduces the diversity of spectral shapes that arise in physically-based models. OXAF accepts three parameters which directly describe the shape of the output ionizing spectrum: the energy of the peak of the accretion disk emission *E _{peak}*, the photon power-law index of the non-thermal X-ray emission Γ, and the proportion of the total flux which is emitted in the non-thermal component

[ascl:1805.014]
OSS: OSSOS Survey Simulator

Comparing properties of discovered trans-Neptunian Objects (TNOs) with dynamical models is impossible due to the observational biases that exist in surveys. The OSSOS Survey Simulator takes an intrinsic orbital model (from, for example, the output of a dynamical Kuiper belt emplacement simulation) and applies the survey biases, so the biased simulated objects can be directly compared with real discoveries.

[ascl:1710.021]
OSIRIS Toolbox: OH-Suppressing InfraRed Imaging Spectrograph pipeline

Lyke, Jim; Do, Tuan; Boehle, Anna; Campbell, Randy; Chappell, Sam; Fitzgerald, Mike; Gasawy, Tom; Iserlohe, Christof; Krabbe, Alfred; Larkin, James; Lockhard, Kelly; Lu, Jessica; Mieda, Etsuko; McElwain, Mike; Perrin, Marshall; Rudy, Alex; Sitarski, Breann; Vayner, Andrey; Walth, Greg; Weiss, Jason; Wizanski, Tommer; Wright, Shelley

OSIRIS Toolbox reduces data for the Keck OSIRIS instrument, an integral field spectrograph that works with the Keck Adaptive Optics System. It offers real-time reduction of raw frames into cubes for display and basic analysis. In this real-time mode, it takes about one minute for a preliminary data cube to appear in the “quicklook” display package. The reduction system also includes a growing set of final reduction steps including correction of telluric absorption and mosaicing of multiple cubes.

[ascl:1204.013]
ORSA: Orbit Reconstruction, Simulation and Analysis

ORSA is an interactive tool for scientific grade Celestial Mechanics computations. Asteroids, comets, artificial satellites, solar and extra-solar planetary systems can be accurately reproduced, simulated, and analyzed. The software uses JPL ephemeris files for accurate planets positions and has a Qt-based graphical user interface. It offers an advanced 2D plotting tool and 3D OpenGL viewer and the standalone numerical library liborsa and can import asteroids and comets from all the known databases (MPC, JPL, Lowell, AstDyS, and NEODyS). In addition, it has an integrated download tool to update databases.

[ascl:1304.012]
ORIGAMI: Structure-finding routine in N-body simulation

ORIGAMI is a dynamical method of determining the morphology of particles in a cosmological simulation by checking for whether, and in how many dimensions, a particle has undergone shell-crossing. The code is written in C and makes use of the Delaunay tessellation calculation routines from the VOBOZ package (which relies on the Qhull package).

[ascl:1409.007]
ORBS: A reduction software for SITELLE and SpiOMM data

ORBS merges, corrects, transforms and calibrates interferometric data cubes and produces a spectral cube of the observed region for analysis. It is a fully automatic data reduction software for use with SITELLE (installed at the Canada-France-Hawaii Telescope) and SpIOMM (a prototype attached to the Observatoire du Mont Mégantic); these imaging Fourier transform spectrometers obtain a hyperspectral data cube which samples a 12 arc-minutes field of view into 4 millions of visible spectra. ORBS is highly parallelized; its core classes (ORB) have been designed to be used in a suite of softwares for data analysis (ORCS and OACS), data simulation (ORUS) and data acquisition (IRIS).

[ascl:1804.009]
orbit-estimation: Fast orbital parameters estimator

orbit-estimation tests and evaluates the Stäckel approximation method for estimating orbit parameters in galactic potentials. It relies on the approximation of the Galactic potential as a Stäckel potential, in a prolate confocal coordinate system, under which the vertical and horizontal motions decouple. By solving the Hamilton Jacobi equations at the turning points of the horizontal and vertical motions, it is possible to determine the spatial boundary of the orbit, and hence calculate the desired orbit parameters.

[ascl:1106.015]
OrbFit: Software to Determine Orbits of Asteroids

OrbFit is a software system allowing one to compute the orbits of asteroids starting from the observations, to propagate these orbits, and to compute predictions on the future (and past) position on the celestial sphere. It is a tool to be used to find a well known asteroid, to recover a lost one, to attribute a small group of observations, to identify two orbits with each other, to study the future (and/or past) close approaches to Earth, thus to assess the risk of an impact, and more.

[ascl:1307.016]
orbfit: Orbit fitting software

Orbfit determines positions and orbital elements, and associated uncertainties, of outer solar system planets. The orbit-fitting procedure is greatly streamlined compared with traditional methods because acceleration can be treated as a perturbation to the inertial motion of the body. Orbfit quickly and accurately calculates orbital elements and ephemerides and their associated uncertainties for targets ≳ 10 AU from the Sun and produces positional estimates and uncertainty ellipses even in the face of the substantial degeneracies of short-arc orbit fits; the sole a priori assumption is that the orbit should be bound or nearly so.

[ascl:1702.001]
ORBE: Orbital integrator for educational purposes

ORBE performs numerical integration of an arbitrary planetary system composed by a central star and up to 100 planets and minor bodies. ORBE calculates the orbital evolution of a system of bodies by means of the computation of the time evolution of their orbital elements. It is easy to use and is suitable for educational use by undergraduate students in the classroom as a first approach to orbital integrators.

[ascl:1210.024]
ORBADV: ORBital ADVection by interpolation

ORBADV adopts a ZEUS-like scheme to solve magnetohydrodynamic equations of motion in a shearing sheet. The magnetic field is discretized on a staggered mesh, and magnetic field variables represent fluxes through zone faces. The code uses obital advection to ensure fast and accurate integration in a large shearing box.

[ascl:1310.001]
ORAC-DR: Astronomy data reduction pipeline

ORAC-DR is a generic data reduction pipeline infrastructure; it includes specific data processing recipes for a number of instruments. It is used at the James Clerk Maxwell Telescope, United Kingdom Infrared Telescope, AAT, and LCOGT. This pipeline runs at the JCMT Science Archive hosted by CADC to generate near-publication quality data products; the code has been in use since 1998.

[ascl:1803.013]
optBINS: Optimal Binning for histograms

optBINS (optimal binning) determines the optimal number of bins in a uniform bin-width histogram by deriving the posterior probability for the number of bins in a piecewise-constant density model after assigning a multinomial likelihood and a non-informative prior. The maximum of the posterior probability occurs at a point where the prior probability and the the joint likelihood are balanced. The interplay between these opposing factors effectively implements Occam's razor by selecting the most simple model that best describes the data.

[submitted]
Opik Collision Probability

The Opik method gives the mean probability of collision of a small body with a given planet. It is a statistical value valid for an orbit with given (a,e,i) and undefined argument of perihelion. In some cases, the planet can eject the small body from the solar system; in these cases, the program estimates the mean time for the ejection. The Opik method does not take into account other perturbers than the planet considered, so it only provides an idea of the timescales involved.

[ascl:1411.004]
OPERA: Open-source Pipeline for Espadons Reduction and Analysis

OPERA (Open-source Pipeline for Espadons Reduction and Analysis) is an open-source collaborative software reduction pipeline for ESPaDOnS data. ESPaDOnS is a bench-mounted high-resolution echelle spectrograph and spectro-polarimeter designed to obtain a complete optical spectrum (from 370 to 1,050 nm) in a single exposure with a mode-dependent resolving power between 68,000 and 81,000. OPERA is fully automated, calibrates on two-dimensional images and reduces data to produce one-dimensional intensity and polarimetric spectra. Spectra are extracted using an optimal extraction algorithm. Though designed for CFHT ESPaDOnS data, the pipeline is extensible to other echelle spectrographs.

[ascl:1509.009]
OPERA: Objective Prism Enhanced Reduction Algorithms

OPERA (Objective Prism Enhanced Reduction Algorithms) automatically analyzes astronomical images using the objective-prism (OP) technique to register thousands of low resolution spectra in large areas. It detects objects in an image, extracts one-dimensional spectra, and identifies the emission line feature. The main advantages of this method are: 1) to avoid subjectivity inherent to visual inspection used in past studies; and 2) the ability to obtain physical parameters without follow-up spectroscopy.

[ascl:1502.002]
OpenOrb: Open-source asteroid orbit computation software

OpenOrb (OOrb) contains tools for rigorously estimating the uncertainties resulting from the inverse problem of computing orbital elements using scarce astrometry. It uses the least-squares method and also contains both Monte-Carlo (MC) and Markov-Chain MC versions of the statistical ranging method. Ranging obtains sampled, non-Gaussian orbital-element probability-density functions and is optimized for cases where the amount of astrometry is scarce or spans a relatively short time interval.

[ascl:1604.001]
OpenMHD: Godunov-type code for ideal/resistive magnetohydrodynamics (MHD)

OpenMHD is a Godunov-type finite-volume code for ideal/resistive magnetohydrodynamics (MHD). It is written in Fortran 90 and is parallelized by using MPI-2 and OpenMP. The code was originally developed for studying magnetic reconnection problems and has been made publicly available in the hope that others may find it useful.

[ascl:1904.024]
OoT: Out-of-Transit Light Curve Generator

OoT (Out-of-Transit) calculates the light curves and radial velocity signals due to a planet orbiting a star. It explicitly models the effects of tides, orbital motion. relativistic beaming, and reflection of the stars light by the planet. The code can also be used to model secondary eclipses.

[ascl:1907.010]
OMNICAL: Redundant calibration code for low frequency radio interferometers

OMNICAL calibrates antennas in the redundant subset of the array. The code consists of two algorithms, a logarithmic method (logcal) and a linearized method (lincal). OMNICAL makes visibilities from physically redundant baselines agree with each other and also explicitly minimizes the variance within redundant visibilities.

[ascl:1806.018]
OMEGA: One-zone Model for the Evolution of GAlaxies

OMEGA (One-zone Model for the Evolution of GAlaxies) calculates the global chemical evolution trends of galaxies. From an input star formation history, it uses SYGMA to create as a function of time multiple simple stellar populations with different masses, ages, and initial compositions. OMEGA offers several prescriptions for modeling the star formation efficiency and the evolution of galactic inflows and outflows. OMEGA is part of the NuGrid (ascl:1610.015) chemical evolution package.

[ascl:1906.015]
OIT: Nonconvex optimization approach to optical-interferometric imaging

In the context of optical interferometry, only undersampled power spectrum and bispectrum data are accessible, creating an ill-posed inverse problem for image recovery. Recently, a tri-linear model was proposed for monochromatic imaging, leading to an alternated minimization problem; in that work, only a positivity constraint was considered, and the problem was solved by an approximated Gauss–Seidel method.

The Optical-Interferometry-Trilinear code improves the approach on three fundamental aspects. First, the estimated image is defined as a solution of a regularized minimization problem, promoting sparsity in a fixed dictionary using either an l1 or a (re)weighted-l1 regularization term. Second, the resultant non-convex minimization problem is solved using a block-coordinate forward–backward algorithm. This algorithm is able to deal both with smooth and non-smooth functions, and benefits from convergence guarantees even in a non-convex context. Finally, the model and algorithm are generalized to the hyperspectral case, promoting a joint sparsity prior through an l2,1 regularization term.

[ascl:1601.004]
Odyssey: Ray tracing and radiative transfer in Kerr spacetime

Odyssey is a GPU-based General Relativistic Radiative Transfer (GRRT) code for computing images and/or spectra in Kerr metric describing the spacetime around a rotating black hole. Odyssey is implemented in CUDA C/C++. For flexibility, the namespace structure in C++ is used for different tasks; the two default tasks presented in the source code are the redshift of a Keplerian disk and the image of a Keplerian rotating shell at 340GHz. Odyssey_Edu, an educational software package for visualizing the ray trajectories in the Kerr spacetime that uses Odyssey, is also available.

[ascl:1810.010]
ODTBX: Orbit Determination Toolbox

ODTBX (Orbit Determination Toolbox) provides orbit determination analysis, advanced mission simulation, and analysis for concept exploration, proposal, early design phase, and/or rapid design center environments. The core ODTBX functionality is realized through a set of estimation commands that incorporate Monte Carlo data simulation, linear covariance analysis, and measurement processing at a generic level; its functions and utilities are combined in a flexible architecture to allow modular development of navigation algorithms and simulations. ODTBX is written in Matlab and Java.

[ascl:1905.021]
ODEPACK: Ordinary differential equation solver library

ODEPACK solves for the initial value problem for ordinary differential equation systems. It consists of nine solvers, a basic solver called LSODE and eight variants of it: LSODES, LSODA, LSODAR, LSODPK, LSODKR, LSODI, LSOIBT, and LSODIS. The collection is suitable for both stiff and nonstiff systems. It includes solvers for systems given in explicit form, dy/dt = f(t,y), and also solvers for systems given in linearly implicit form, A(t,y) dy/dt = g(t,y). The ODEPACK solvers are written in standard Fortran and there are separate double and single precision versions. Each solver consists of a main driver subroutine having the same name as the solver and some number of subordinate routines. For each solver, there is also a demonstration program, which solves one or two simple problems in a somewhat self-checking manner.

[ascl:1010.048]
OCTGRAV: Sparse Octree Gravitational N-body Code on Graphics Processing Units

Octgrav is a very fast tree-code which runs on massively parallel Graphical Processing Units (GPU) with NVIDIA CUDA architecture. The algorithms are based on parallel-scan and sort methods. The tree-construction and calculation of multipole moments is carried out on the host CPU, while the force calculation which consists of tree walks and evaluation of interaction list is carried out on the GPU. In this way, a sustained performance of about 100GFLOP/s and data transfer rates of about 50GB/s is achieved. It takes about a second to compute forces on a million particles with an opening angle of $ heta approx 0.5$.

To test the performance and feasibility, we implemented the algorithms in CUDA in the form of a gravitational tree-code which completely runs on the GPU. The tree construction and traverse algorithms are portable to many-core devices which have support for CUDA or OpenCL programming languages. The gravitational tree-code outperforms tuned CPU code during the tree-construction and shows a performance improvement of more than a factor 20 overall, resulting in a processing rate of more than 2.8 million particles per second.

The code has a convenient user interface and is freely available for use.

[ascl:1812.018]
OctApps: Octave functions for continuous gravitational-wave data analysis

Wette, Karl; Prix, Reinhard; Keitel, David; Pitkin, Matthew; Dreissigacker, Christoph; Whelan, John T.; Leaci, Paola

The OctApps library provides various functions, written in Octave, for performing searches for the weak signatures of continuous gravitational waves from rapidly-rotating neutron stars amidst the instrumental noise of the LIGO and Virgo detectors.

[ascl:1901.002]
OCFit: Python package for fitting of O-C diagrams

OCFit fits and analyzes O-C diagrams using Genetic Algorithms and Markov chain Monte Carlo methods. The MC method is used to determine a very good estimation of errors of the parameters. Unlike some other fitting routines, OCFit does not need any initial values of fitted parameters. An intuitive graphic user interface is provided for ease of fitting, and nine common models of periodic O-C changes are included.

[submitted]
OCD: O'Connell Effect Detector using Push-Pull Learning

OCD (O'Connell Effect Detector using Push-Pull Learning) detects eclipsing binaries that demonstrate the O'Connell Effect. This time-domain signature extraction methodology uses a supporting supervised pattern detection algorithm. The methodology maps stellar variable observations (time-domain data) to a new representation known as Distribution Fields (DF), the properties of which enable efficient handling of issues such as irregular sampling and multiple values per time instance. Using this representation, the code applies a metric learning technique directly on the DF space capable of specifically identifying the stars of interest; the metric is tuned on a set of labeled eclipsing binary data from the Kepler survey, targeting particular systems exhibiting the O’Connell Effect. This code is useful for large-scale data volumes such as that expected from next generation telescopes such as LSST.

[ascl:1011.017]
Occultation and Microlensing

Occultation and microlensing are different limits of the same phenomena of one body passing in front of another body. We derive a general exact analytic expression which describes both microlensing and occultation in the case of spherical bodies with a source of uniform brightness and a non-relativistic foreground body. We also compute numerically the case of a source with quadratic limb-darkening. In the limit that the gravitational deflection angle is comparable to the angular size of the foreground body, both microlensing and occultation occur as the objects align. Such events may be used to constrain the size ratio of the lens and source stars, the limb-darkening coefficients of the source star, and the surface gravity of the lens star (if the lens and source distances are known). Application of these results to microlensing during transits in binaries and giant-star microlensing are discussed. These results unify the microlensing and occultation limits and should be useful for rapid model fitting of microlensing, eclipse, and "microccultation" events.

[ascl:1307.008]
Obit: Radio Astronomy Data Handling

Obit is a group of software packages for handling radio astronomy data, especially interferometric and single dish OTF imaging. Obit is primarily an environment in which new data processing algorithms can be developed and tested but which can also be used for production processing of a certain range of scientific problems. The package supports both prepackaged, compiled tasks and a python interface to the major class functionality to allow rapid prototyping using python scripts; it allows access to multiple disk--resident data formats, in particular access to either AIPS disk data or FITS files. Obit applications are interoperable with Classic AIPS and the ObitTalk python interface gives access to AIPS tasks as well as Obit libraries and tasks.

[ascl:1608.012]
OBERON: OBliquity and Energy balance Run on N-body systems

OBERON (OBliquity and Energy balance Run on N-body systems) models the climate of Earthlike planets under the effects of an arbitrary number and arrangement of other bodies, such as stars, planets and moons. The code, written in C++, simultaneously computes N body motions using a 4th order Hermite integrator, simulates climates using a 1D latitudinal energy balance model, and evolves the orbital spin of bodies using the equations of Laskar (1986a,b).

[ascl:1408.019]
O_{2}scl: Object-oriented scientific computing library

O_{2}scl is an object-oriented library for scientific computing in C++ useful for solving, minimizing, differentiating, integrating, interpolating, optimizing, approximating, analyzing, fitting, and more. Many classes operate on generic function and vector types; it includes classes based on GSL and CERNLIB. O_{2}scl also contains code for computing the basic thermodynamic integrals for fermions and bosons, for generating almost all of the most common equations of state of nuclear and neutron star matter, and for solving the TOV equations. O_{2}scl can be used on Linux, Mac and Windows (Cygwin) platforms and has extensive documentation.

[ascl:1712.006]
Nyx: Adaptive mesh, massively-parallel, cosmological simulation code

Nyx code solves equations of compressible hydrodynamics on an adaptive grid hierarchy coupled with an N-body treatment of dark matter. The gas dynamics in Nyx use a finite volume methodology on an adaptive set of 3-D Eulerian grids; dark matter is represented as discrete particles moving under the influence of gravity. Particles are evolved via a particle-mesh method, using Cloud-in-Cell deposition/interpolation scheme. Both baryonic and dark matter contribute to the gravitational field. In addition, Nyx includes physics for accurately modeling the intergalactic medium; in optically thin limits and assuming ionization equilibrium, the code calculates heating and cooling processes of the primordial-composition gas in an ionizing ultraviolet background radiation field.

[ascl:1610.015]
NuPyCEE: NuGrid Python Chemical Evolution Environment

The NuGrid Python Chemical Evolution Environment (NuPyCEE) simulates the chemical enrichment and stellar feedback of stellar populations. It contains three modules. The Stellar Yields for Galactic Modeling Applications module (SYGMA) models the enrichment and feedback of simple stellar populations which can be included in hydrodynamic simulations and semi-analytic models of galaxies. It is the basic building block of the One-zone Model for the Evolution of GAlaxies (OMEGA, ascl:1806.018) module which models the chemical evolution of galaxies such as the Milky Way and its dwarf satellites. The STELLAB (STELLar ABundances) module provides a library of observed stellar abundances useful for comparing predictions of SYGMA and OMEGA.

[ascl:1408.013]
NumCosmo: Numerical Cosmology

NumCosmo is a free software C library whose main purposes are to test cosmological models using observational data and to provide a set of tools to perform cosmological calculations. The software implements three different probes: cosmic microwave background (CMB), supernovae type Ia (SNeIa) and large scale structure (LSS) information, such as baryonic acoustic oscillations (BAO) and galaxy cluster abundance. The code supports a joint analysis of these data and the parameter space can include cosmological and phenomenological parameters. NumCosmo matter power spectrum and CMB codes were written independent of other implementations such as CMBFAST (ascl:9909.004), CAMB (ascl:1102.026), etc.

The library structure simplifies the inclusion of non-standard cosmological models. Besides the functions related to cosmological quantities, this library also implements mathematical and statistical tools. The former were developed to enable the inclusion of other probes and/or theoretical models and to optimize the codes. The statistical framework comprises algorithms which define likelihood functions, minimization, Monte Carlo, Fisher Matrix and profile likelihood methods.

[ascl:1601.014]
Nulike: Neutrino telescope likelihood tools

Nulike is software for including full event-level information in likelihood calculations for neutrino telescope searches for dark matter annihilation. It includes both angular and spectral information about neutrino events as well as their total number, and can be used for single models without reference to the rest of a parameter space.

[ascl:1904.030]
nudec_BSM: Neutrino Decoupling Beyond the Standard Model

nudec_BSM uses a simplified approach to solve for the neutrino decoupling, allowing one to capture the time dependence of the process while accounting for all possible interactions that can alter it.

[ascl:1602.008]
NuCraft: Oscillation probabilities for atmospheric neutrinos calculator

NuCraft calculates oscillation probabilities for atmospheric neutrinos, taking into account matter effects and the Earth's atmosphere, and supports an arbitrary number of sterile neutrino flavors with easily configurable continuous Earth models. Continuous modeling of the Earth instead of the often-used approximation of four layers with constant density and consideration of the smearing of baseline lengths due to the variable neutrino production heights in Earth's atmosphere each lead to deviations of 10% or more for conventional neutrinos between 1 and 10 GeV.

[ascl:1609.009]
NSCool: Neutron star cooling code

NSCool is a 1D (i.e., spherically symmetric) neutron star cooling code written in Fortran 77. The package also contains a series of EOSs (equation of state) to build stars, a series of pre-built stars, and a TOV (Tolman- Oppenheimer-Volkoff) integrator to build stars from an EOS. It can also handle “strange stars” that have a huge density discontinuity between the quark matter and the covering thin baryonic crust. NSCool solves the heat transport and energy balance equations in whole GR, resulting in a time sequence of temperature profiles (and, in particular, a Teff - age curve). Several heating processes are included, and more can easily be incorporated. In particular it can evolve a star undergoing accretion with the resulting deep crustal heating, under a steady or time-variable accretion rate. NSCool is robust, very fast, and highly modular, making it easy to add new subroutines for new processes.

[ascl:1807.025]
NRPy+: Code generator for Numerical Relativity

NRPy+ (Python-based Code generation for Numerical Relativity and Beyond) generates highly-optimized C code from complex tensorial expressions input in Einstein-like notation. NRPy+ uses SymPy as its computer algebra system backend. It is part of the NRPy+/SENR numerical relativity code package for solving Einstein's equations of general relativity to model compact objects at about 1/100 the cost in memory of more traditional, AMR-based numerical relativity codes, thus allowing desktop computers to be used for gravitational wave astrophysics.

[ascl:1804.015]
NR-code: Nonlinear reconstruction code

NR-code applies nonlinear reconstruction to the dark matter density field in redshift space and solves for the nonlinear mapping from the initial Lagrangian positions to the final redshift space positions; this reverses the large-scale bulk flows and improves the precision measurement of the baryon acoustic oscillations (BAO) scale.

[ascl:1705.014]
NPTFit: Non-Poissonian Template Fitting

NPTFit is a specialized Python/Cython package that implements Non-Poissonian Template Fitting (NPTF), originally developed for characterizing populations of unresolved point sources. It offers fast evaluation of likelihoods for NPTF analyses and has an easy-to-use interface for performing non-Poissonian (as well as standard Poissonian) template fits using MultiNest (ascl:1109.006) or other inference tools. It allows inclusion of an arbitrary number of point source templates, with an arbitrary number of degrees of freedom in the modeled flux distribution, and has modules for analyzing and plotting the results of an NPTF.

[ascl:1202.003]
NOVAS: Naval Observatory Vector Astrometry Software

Kaplan, George; Bartlett, Jennifer Lynn; Monet, Alice; Bangert, John; Puatua, Wendy; Harris, William; Fredericks, Amy; Barron, Eric G.; Barrett, Paul

NOVAS is an integrated package of subroutines and functions for computing various commonly needed quantities in positional astronomy. The package can provide, in one or two subroutine or function calls, the instantaneous coordinates of any star or planet in a variety of coordinate systems. At a lower level, NOVAS also supplies astrometric utility transformations, such as those for precession, nutation, aberration, parallax, and the gravitational deflection of light. The computations are accurate to better than one milliarcsecond. The NOVAS package is an easy-to-use facility that can be incorporated into data reduction programs, telescope control systems, and simulations. The U.S. parts of The Astronomical Almanac are prepared using NOVAS. Three editions of NOVAS are available: Fortran, C, and Python.

[ascl:1011.016]
Non-LTE Models and Theoretical Spectra of Accretion Disks in Active Galactic Nuclei. III. Integrated Spectra for Hydrogen-Helium Disks

We have constructed a grid of non-LTE disk models for a wide range of black hole mass and mass accretion rate, for several values of viscosity parameter alpha, and for two extreme values of the black hole spin: the maximum-rotation Kerr black hole, and the Schwarzschild (non-rotating) black hole. Our procedure calculates self-consistently the vertical structure of all disk annuli together with the radiation field, without any approximations imposed on the optical thickness of the disk, and without any ad hoc approximations to the behavior of the radiation intensity. The total spectrum of a disk is computed by summing the spectra of the individual annuli, taking into account the general relativistic transfer function. The grid covers nine values of the black hole mass between M = 1/8 and 32 billion solar masses with a two-fold increase of mass for each subsequent value; and eleven values of the mass accretion rate, each a power of 2 times 1 solar mass/year. The highest value of the accretion rate corresponds to 0.3 Eddington. We show the vertical structure of individual annuli within the set of accretion disk models, along with their local emergent flux, and discuss the internal physical self-consistency of the models. We then present the full disk-integrated spectra, and discuss a number of observationally interesting properties of the models, such as optical/ultraviolet colors, the behavior of the hydrogen Lyman limit region, polarization, and number of ionizing photons. Our calculations are far from definitive in terms of the input physics, but generally we find that our models exhibit rather red optical/UV colors. Flux discontinuities in the region of the hydrogen Lyman limit are only present in cool, low luminosity models, while hotter models exhibit blueshifted changes in spectral slope.

[ascl:1305.013]
Non-Gaussian Realisations

Non-Gaussian Realisations provides code based on a spectral distortion/quantile transformation that generates a realization of a field on a cubic grid that has a specified probability distribution function and a specified power spectrum.

[ascl:1711.024]
NOD3: Single dish reduction software

NOD3 processes and analyzes maps from single-dish observations affected by scanning effects from clouds, receiver instabilities, or radio-frequency interference. Its “basket-weaving” tool combines orthogonally scanned maps into a final map that is almost free of scanning effects. A restoration tool for dual-beam observations reduces the noise by a factor of about two compared to the NOD2 version. Combining single-dish with interferometer data in the map plane ensures the full recovery of the total flux density.

[ascl:1101.006]
NIRVANA: A Numerical Tool for Astrophysical Gas Dynamics

The NIRVANA code is capable of the simulation of multi-scale self-gravitational magnetohydrodynamics problems in three space dimensions employing the technique of adaptive mesh refinement. The building blocks of NIRVANA are (i) a fully conservative, divergence-free Godunov-type central scheme for the solution of the equations of magnetohydrodynamics; (ii) a block-structured mesh refinement algorithm which automatically adds and removes elementary grid blocks whenever necessary to achieve adequate resolution and; (iii) an adaptive mesh Poisson solver based on multigrid philosophy which incorporates the so-called elliptic matching condition to keep the gradient of the gravitational potential continous at fine/coarse mesh interfaces.

[ascl:1501.002]
NIGO: Numerical Integrator of Galactic Orbits

NIGO (Numerical Integrator of Galactic Orbits) predicts the orbital evolution of test particles moving within a fully-analytical gravitational potential generated by a multi-component galaxy. The code can simulate the orbits of stars in elliptical and disc galaxies, including non-axisymmetric components represented by a spiral pattern and/or rotating bar(s).

[ascl:1106.016]
Nightfall: Animated Views of Eclipsing Binary Stars

Nightfall is an astronomy application for fun, education, and science. It can produce animated views of eclipsing binary stars, calculate synthetic lightcurves and radial velocity curves, and eventually determine the best-fit model for a given set of observational data of an eclipsing binary star system.

Nightfall comes with a user guide and a set of observational data for several eclipsing binary star systems.

[ascl:1903.008]
NIFTy5: Numerical Information Field Theory v5

Arras, Philipp; Baltac, Mihai; Ensslin, Torsten A.; Frank, Philipp; Hutschenreuter, Sebastian; Knollmueller, Jakob; Leike, Reimar; Newrzella, Max-Niklas; Platz, Lukas; Reinecke, Martin; Stadler, Julia

NIFTy (Numerical Information Field Theory) facilitates the construction of Bayesian field reconstruction algorithms for fields being defined over multidimensional domains. A NIFTy algorithm can be developed for 1D field inference and then be used in 2D or 3D, on the sphere, or on product spaces thereof. NIFTy5 is a complete redesign of the previous framework (ascl:1302.013), and requires only the specification of a probabilistic generative model for all involved fields and the data in order to be able to recover the former from the latter. This is achieved via Metric Gaussian Variational Inference, which also provides posterior samples for all unknown quantities jointly.

[ascl:1302.013]
NIFTY: A versatile Python library for signal inference

Selig, Marco; Bell, Michael R.; Junklewitz, Henrik; Oppermann, Niels; Reinecke, Martin; Greiner, Maksim; Pachajoa, Carlos; Ensslin, Torsten A.

NIFTY (Numerical Information Field TheorY) is a versatile library enables the development of signal inference algorithms that operate regardless of the underlying spatial grid and its resolution. Its object-oriented framework is written in Python, although it accesses libraries written in Cython, C++, and C for efficiency. NIFTY offers a toolkit that abstracts discretized representations of continuous spaces, fields in these spaces, and operators acting on fields into classes. Thereby, the correct normalization of operations on fields is taken care of automatically. This allows for an abstract formulation and programming of inference algorithms, including those derived within information field theory. Thus, NIFTY permits rapid prototyping of algorithms in 1D and then the application of the developed code in higher-dimensional settings of real world problems. NIFTY operates on point sets, n-dimensional regular grids, spherical spaces, their harmonic counterparts, and product spaces constructed as combinations of those.

[ascl:1508.002]
NICOLE: NLTE Stokes Synthesis/Inversion Code

NICOLE, written in Fortran 90, seeks the model atmosphere that provides the best fit to the Stokes profiles (in a least-squares sense) of an arbitrary number of simultaneously-observes spectral lines from solar/stellar atmospheres. The inversion core used for the development of NICOLE is the LORIEN engine (the Lovely Reusable Inversion ENgine), which combines the SVD technique with the Levenberg-Marquardt minimization method to solve the inverse problem.

[ascl:1608.016]
NICIL: Non-Ideal magnetohydrodynamics Coefficients and Ionisation Library

NICIL (Non-Ideal magnetohydrodynamics Coefficients and Ionisation Library) calculates the ionization values and the coefficients of the non-ideal magnetohydrodynamics terms of Ohmic resistivity, the Hall effect, and ambipolar diffusion. Written as a standalone Fortran90 module that can be implemented in existing codes, NICIL is fully parameterizable, allowing the user to choose which processes to include and decide the values of the free parameters. The module includes both cosmic ray and thermal ionization; the former includes two ion species and three species of dust grains (positively charged, negatively charged and neutral), and the latter includes five elements which can be doubly ionized.

[ascl:1508.008]
NGMIX: Gaussian mixture models for 2D images

NGMIX implements Gaussian mixture models for 2D images. Both the PSF profile and the galaxy are modeled using mixtures of Gaussians. Convolutions are thus performed analytically, resulting in fast model generation as compared to methods that perform the convolution in Fourier space. For the galaxy model, NGMIX supports exponential disks and de Vaucouleurs and Sérsic profiles; these are implemented approximately as a sum of Gaussians using the fits from Hogg & Lang (2013). Additionally, any number of Gaussians can be fit, either completely free or constrained to be cocentric and co-elliptical.

[ascl:1903.013]
NFWdist: Density, distribution function, quantile function and random generation for the 3D NFW profile

Available in R and Python, the simple analytic scheme NFWdist performs highly efficient and exact sampling of the Navarro, Frenk & White (NFW) profile as a true probability distribution function, with the only variable being the concentration.

[ascl:1807.011]
nfield: Stochastic tool for QFT on inflationary backgrounds

nfield uses a stochastic formalism to compute the IR correlation functions of quantum fields during cosmic inflation in n-field dimensions. This is a necessary 1-loop resummation of the correlation functions to render them finite. The code supports the implementation of n-numbers of coupled test fields (energetically sub-dominant) as well as non-test fields.

[ascl:1010.085]
Network Tools for Astronomical Data Retrieval

The first step in a science project is the acquisition and understanding of the relevant data. The tools range from simple data transfer methods to more complex browser-emulating scripts. When integrated with a defined sample or catalog, these scripts provide seamless techniques to retrieve and store data of varying types. These tools can be used to leapfrog from website to website to acquire multi-wavelength datasets. This project demonstrates the capability to use multiple data websites, in conjunction, to perform the type of calculations once reserved for on-site datasets.

[ascl:1809.012]
nestcheck: Nested sampling calculations analysis

Nestcheck analyzes nested sampling runs and estimates numerical uncertainties on calculations using them. The package can load results from a number of nested sampling software packages, including MultiNest (ascl:1109.006), PolyChord (ascl:1502.011), dynesty (ascl:1809.013) and perfectns (ascl:1809.005), and offers the flexibility to add input functions for other nested sampling software packages. Nestcheck utilities include error analysis, diagnostic tests, and plots for nested sampling calculations.

[ascl:1307.017]
NEST: Noble Element Simulation Technique

Szydagis, M.; Barry, N.; Kazkaz, K.; Mock, J.; Stolp, D.; Sweany, M.; Tripathi, M.; Uvarov, S.; Walsh, N.; Woods, M.

NEST (Noble Element Simulation Technique) offers comprehensive, accurate, and precise simulation of the excitation, ionization, and corresponding scintillation and electroluminescence processes in liquid noble elements, useful for direct dark matter detectors, double beta decay searches, PET scans, and general radiation detection technology. Written in C++, NEST is an add-on module for the Geant4 simulation package that incorporates more detailed physics than is currently available into the simulation of scintillation. NEST is of particular use for low-energy nuclear recoils. All available liquid xenon data on nuclear recoils and electron recoils to date have been taken into consideration in arriving at the current models. NEST also handles the magnitude of the light and charge yields of nuclear recoils, including their electric field dependence, thereby shedding light on the possibility of detection or exclusion of a low-mass dark matter WIMP by liquid xenon detectors.

[ascl:1010.051]
NEMO: A Stellar Dynamics Toolbox

NEMO is an extendible Stellar Dynamics Toolbox, following an Open-Source Software model. It has various programs to create, integrate, analyze and visualize N-body and SPH like systems, following the pipe and filter architecture. In addition there are various tools to operate on images, tables and orbits, including FITS files to export/import to/from other astronomical data reduction packages. A large growing fraction of NEMO has been contributed by a growing list of authors. The source code consist of a little over 4000 files and a little under 1,000,000 lines of code and documentation, mostly C, and some C++ and Fortran. NEMO development started in 1986 in Princeton (USA) by Barnes, Hut and Teuben. See also ZENO (ascl:1102.027) for the version that Barnes maintains.

[ascl:1010.004]
Needatool: A Needlet Analysis Tool for Cosmological Data Processing

NeedATool (Needlet Analysis Tool) performs data analysis based on needlets, a wavelet rendition powerful for the analysis of fields defined on a sphere. Needlets have been applied successfully to the treatment of astrophysical and cosmological observations, particularly to the analysis of cosmic microwave background (CMB) data. Wavelets have emerged as a useful tool for CMB data analysis, as they combine most of the advantages of both pixel space, where it is easier to deal with partial sky coverage and experimental noise, and the harmonic domain, in which beam treatment and comparison with theoretical predictions are more effective due in large part to their sharp localization.

[ascl:1608.019]
NEBULAR: Spectrum synthesis for mixed hydrogen-helium gas in ionization equilibrium

NEBULAR synthesizes the spectrum of a mixed hydrogen helium gas in collisional ionization equilibrium. It is not a spectral fitting code, but it can be used to resample a model spectrum onto the wavelength grid of a real observation. It supports a wide range of temperatures and densities. NEBULAR includes free-free, free-bound, two-photon and line emission from HI, HeI and HeII. The code will either return the composite model spectrum, or, if desired, the unrescaled atomic emission coefficients. It is written in C++ and depends on the GNU Scientific Library (GSL).

[ascl:1809.009]
NEBULA: Radiative transfer code of ionized nebulae at radio wavelengths

NEBULA performs the radiative transfer of the 3He+ hyperfine transition, radio recombination lines (RRLs), and free-free continuum emission through a model nebula. The model nebula is composed of only H and He within a three-dimension Cartesian grid with arbitrary density, temperature, and ionization structure. The 3He+ line is assumed to be in local thermodynamic equilibrium (LTE), but non-LTE effects and pressure broadening from electron impacts can be included for the RRLs. All spectra are broadened by thermal and microturbulent motions.

[ascl:1411.013]
NEAT: Nebular Empirical Analysis Tool

NEAT is a fully automated code which carries out a complete analysis of lists of emission lines to estimate the amount of interstellar extinction, calculate representative temperatures and densities, compute ionic abundances from both collisionally excited lines and recombination lines, and finally to estimate total elemental abundances using an ionization correction scheme. NEAT uses a Monte Carlo technique to robustly propagate uncertainties from line flux measurements through to the derived abundances.

[ascl:1101.002]
NDSPMHD Smoothed Particle Magnetohydrodynamics Code

This paper presents an overview and introduction to Smoothed Particle Hydrodynamics and Magnetohydrodynamics in theory and in practice. Firstly, we give a basic grounding in the fundamentals of SPH, showing how the equations of motion and energy can be self-consistently derived from the density estimate. We then show how to interpret these equations using the basic SPH interpolation formulae and highlight the subtle difference in approach between SPH and other particle methods. In doing so, we also critique several `urban myths' regarding SPH, in particular the idea that one can simply increase the `neighbour number' more slowly than the total number of particles in order to obtain convergence. We also discuss the origin of numerical instabilities such as the pairing and tensile instabilities. Finally, we give practical advice on how to resolve three of the main issues with SPMHD: removing the tensile instability, formulating dissipative terms for MHD shocks and enforcing the divergence constraint on the particles, and we give the current status of developments in this area. Accompanying the paper is the first public release of the NDSPMHD SPH code, a 1, 2 and 3 dimensional code designed as a testbed for SPH/SPMHD algorithms that can be used to test many of the ideas and used to run all of the numerical examples contained in the paper.

[ascl:1411.023]
NDF: Extensible N-dimensional Data Format Library

The Extensible N-Dimensional Data Format (NDF) stores bulk data in the form of N-dimensional arrays of numbers. It is typically used for storing spectra, images and similar datasets with higher dimensionality. The NDF format is based on the Hierarchical Data System (HDS) and is extensible; not only does it provide a comprehensive set of standard ancillary items to describe the data, it can also be extended indefinitely to handle additional user-defined information of any type. The NDF library is used to read and write files in the NDF format. It is distributed with the Starlink software (ascl:1110.012).

[ascl:1010.019]
NBSymple: A Double Parallel, Symplectic N-body Code Running on Graphic Processing Units

NBSymple is a numerical code which numerically integrates the equation of motions of N 'particles' interacting via Newtonian gravitation and move in an external galactic smooth field. The force evaluation on every particle is done by mean of direct summation of the contribution of all the other system's particle, avoiding truncation error. The time integration is done with second-order and sixth-order symplectic schemes. NBSymple has been parallelized twice, by mean of the Computer Unified Device Architecture to make the all-pair force evaluation as fast as possible on high-performance Graphic Processing Units NVIDIA TESLA C 1060, while the O(N) computations are distributed on various CPUs by mean of OpenMP Application Program. The code works both in single precision floating point arithmetics or in double precision. The use of single precision allows the use at best of the GPU performances but, of course, limits the precision of simulation in some critical situations. We find a good compromise in using a software reconstruction of double precision for those variables that are most critical for the overall precision of the code.

[ascl:1904.027]
nbodykit: Massively parallel, large-scale structure toolkit

nbodykit provides algorithms for analyzing cosmological datasets from N-body simulations and large-scale structure surveys, and takes advantage of the abundance and availability of large-scale computing resources. The package provides a unified treatment of simulation and observational datasets by insulating algorithms from data containers, and reduces wall-clock time by scaling to thousands of cores. All algorithms are parallel and run with Message Passing Interface (MPI); the code is designed to be deployed on large super-computing facilities. nbodykit offers an interactive user interface that performs as well in a Jupyter notebook as on super-computing machines.

[ascl:1502.010]
nbody6tt: Tidal tensors in N-body simulations

nbody6tt, based on Aarseth's nbody6 (ascl:1102.006) code, includes the treatment of complex galactic tides in a direct N-body simulation of a star cluster through the use of tidal tensors (tt) and offers two complementary methods. The first allows consideration of any kind of galaxy and orbit, thus offering versatility; this method cannot be used to study tidal debris, as it relies on the tidal approximation (linearization of the tidal force). The second method is not limited by this and does not require a galaxy simulation; the user defines a numerical function which takes position and time as arguments, and the galactic potential is returned. The space and time derivatives of the potential are used to (i) integrate the motion of the cluster on its orbit in the galaxy (starting from user-defined initial position and velocity vector), and (ii) compute the tidal acceleration on the stars.

[ascl:1102.006]
NBODY Codes: Numerical Simulations of Many-body (N-body) Gravitational Interactions

I review the development of direct N-body codes at Cambridge over nearly 40 years, highlighting the main stepping stones. The first code (NBODY1) was based on the simple concepts of a force polynomial combined with individual time steps, where numerical problems due to close encounters were avoided by a softened potential. Fortuitously, the elegant Kustaanheimo-Stiefel two-body regularization soon permitted small star clusters to be studied (NBODY3). Subsequent extensions to unperturbed three-body and four-body regularization proved beneficial in dealing with multiple interactions. Investigations of larger systems became possible with the Ahmad-Cohen neighbor scheme which was used more than 20 years ago for expanding universe models of 4000 galaxies (NBODY2). Combining the neighbor scheme with the regularization procedures enabled more realistic star clusters to be considered (NBODY5). After a period of simulations with no apparent technical progress, chain regularization replaced the treatment of compact subsystems (NBODY3, NBODY5). More recently, the Hermite integration method provided a major advance and has been implemented on the special-purpose HARP computers (NBODY4) together with an alternative version for workstations and supercomputers (NBODY6). These codes also include a variety of algorithms for stellar evolution based on fast lookup functions. The treatment of primordial binaries contains efficient procedures for chaotic two-body motion as well as tidal circularization, and special attention is paid to hierarchical systems and their stability. This family of N-body codes constitutes a powerful tool for dynamical simulations which is freely available to the astronomical community, and the massive effort owes much to collaborators.

[ascl:1905.020]
NAPLES: Numerical Analysis of PLanetary EncounterS

NAPLES (Numerical Analysis of PLanetary EncounterS) performs batch propagations of close encounters in the three-body problem and computes the numerical error with respect to reference trajectories computed in quadruple precision. It uses the LSODAR integrator from ODEPACK (ascl:1905.021) and the equations of motion correspond to several regularized formulations.

[ascl:1803.004]
nanopipe: Calibration and data reduction pipeline for pulsar timing

nanopipe is a data reduction pipeline for calibration, RFI removal, and pulse time-of-arrival measurement from radio pulsar data. It was developed primarily for use by the NANOGrav project. nanopipe is written in Python, and depends on the PSRCHIVE (ascl:1105.014) library.

[ascl:1708.022]
Naima: Derivation of non-thermal particle distributions through MCMC spectral fitting

Naima computes non-thermal radiation from relativistic particle populations. It includes tools to perform MCMC fitting of radiative models to X-ray, GeV, and TeV spectra using emcee (ascl:1303.002), an affine-invariant ensemble sampler for Markov Chain Monte Carlo. Naima is an Astropy (ascl:1304.002) affiliated package.

[ascl:1409.009]
Nahoon: Time-dependent gas-phase chemical model

Nahoon is a gas-phase chemical model that computes the chemical evolution in a 1D temperature and density structure. It uses chemical networks downloaded from the KInetic Database for Astrochemistry (KIDA) but the model can be adapted to any network. The program is written in Fortran 90 and uses the DLSODES (double precision) solver from the ODEPACK package (ascl:1905.021) to solve the coupled stiff differential equations. The solver computes the chemical evolution of gas-phase species at a fixed temperature and density and can be used in one dimension (1D) if a grid of temperature, density, and visual extinction is provided. Grains, both neutral and negatively charged, and electrons are considered as chemical species and their concentrations are computed at the same time as those of the other species. Nahoon contains a test to check the temperature range of the validity of the rate coefficients and avoid extrapolations outside this range. A test is also included to check for duplication of chemical reactions, defined over complementary ranges of temperature.

[ascl:1411.014]
NAFE: Noise Adaptive Fuzzy Equalization

NAFE (Noise Adaptive Fuzzy Equalization) is an image processing method allowing for visualization of fine structures in SDO AIA high dynamic range images. It produces artifact-free images and gives significantly better results than methods based on convolution or Fourier transform.

[ascl:1102.001]
N-MODY: A Code for Collisionless N-body Simulations in Modified Newtonian Dynamics

N-MODY is a parallel particle-mesh code for collisionless N-body simulations in modified Newtonian dynamics (MOND). N-MODY is based on a numerical potential solver in spherical coordinates that solves the non-linear MOND field equation, and is ideally suited to simulate isolated stellar systems. N-MODY can be used also to compute the MOND potential of arbitrary static density distributions. A few applications of N-MODY indicate that some astrophysically relevant dynamical processes are profoundly different in MOND and in Newtonian gravity with dark matter.

[ascl:1502.003]
N-GenIC: Cosmological structure initial conditions

N-GenIC is an initial conditions code for cosmological structure formation that can be used to set-up random N-body realizations of Gaussian random fields with a prescribed power spectrum in a homogeneously sampled periodic box. The code creates cosmological initial conditions based on the Zeldovich approximation, in a format directly compatible with GADGET or AREPO.

[ascl:1203.009]
MYRIAD: N-body code for simulations of star clusters

MYRIAD is a C++ code for collisional N-body simulations of star clusters. The code uses the Hermite fourth-order scheme with block time steps, for advancing the particles in time, while the forces and neighboring particles are computed using the GRAPE-6 board. Special treatment is used for close encounters, binary and multiple sub-systems that either form dynamically or exist in the initial configuration. The structure of the code is modular and allows the appropriate treatment of more physical phenomena, such as stellar and binary evolution, stellar collisions and evolution of close black-hole binaries. Moreover, it can be easily modified so that the part of the code that uses GRAPE-6 could be replaced by another module that uses other accelerating-hardware like the Graphics Processing Units (GPUs). Appropriate choice of the free parameters give a good accuracy and speed for simulations of star clusters up to and beyond core collapse. The code accuracy becomes comparable and even better than the accuracy of existing codes when a number of close binary systems is dynamically created in a simulation; this is due to the high accuracy of the method that is used for close binary and multiple sub-systems. The code can be used for evolving star clusters containing equal-mass stars or star clusters with an initial mass function (IMF) containing an intermediate mass black hole (IMBH) at the center and/or a fraction of primordial binaries, which are systems of particular astrophysical interest.

[ascl:1311.011]
MUSIC: MUlti-Scale Initial Conditions

MUSIC generates multi-scale initial conditions with multiple levels of refinements for cosmological ‘zoom-in’ simulations. The code uses an adaptive convolution of Gaussian white noise with a real-space transfer function kernel together with an adaptive multi-grid Poisson solver to generate displacements and velocities following first- (1LPT) or second-order Lagrangian perturbation theory (2LPT). MUSIC achieves rms relative errors of the order of 10−4 for displacements and velocities in the refinement region and thus improves in terms of errors by about two orders of magnitude over previous approaches. In addition, errors are localized at coarse-fine boundaries and do not suffer from Fourier space-induced interference ringing.

[ascl:1610.004]
MUSE-DRP: MUSE Data Reduction Pipeline

The MUSE pipeline turns the complex raw data of the MUSE integral field spectrograph into a ready-to-use datacube for scientific analysis.

[ascl:1605.007]
MUSCLE: MUltiscale Spherical-ColLapse Evolution

MUSCLE (MUltiscale Spherical ColLapse Evolution) produces low-redshift approximate N-body realizations accurate to few-Megaparsec scales. It applies a spherical-collapse prescription on multiple Gaussian-smoothed scales. It achieves higher accuracy than perturbative schemes (Zel'dovich and second-order Lagrangian perturbation theory - 2LPT), and by including the void-in-cloud process (voids in large-scale collapsing regions), solves problems with a single-scale spherical-collapse scheme.

[ascl:1402.006]
Munipack: General astronomical image processing software

Munipack provides easy-to-use tools for all astronomical astrometry and photometry, access to Virtual Observatory as well as FITS files operations and a simple user interface along with a powerful processing engine. Its many features include a FITS images viewer that allows for basic (astronomical) operations with frames, advanced image processor supporting an infinite dynamic range and advanced color management, and astrometric calibration of images. The astrometry module uses robust statistical estimators and algorithms. The photometry module provides the classical method detection of stars and implements the aperture photometry, calibrated on the basis of photon statistics, and allows for the automatic detection and aperture photometry of stars; calibration on absolute fluxes is possible. The software also provides a standard way to correct for all the bias, dark and flat-field frames, and many other features.

[ascl:1704.014]
Multipoles: Potential gain for binary lens estimation

Multipoles, written in Python, calculates the quadrupole and hexadecapole approximations of the finite-source magnification: quadrupole (Wk,rho,Gamma) and hexadecapole (Wk,rho,Gamma). The code is efficient and faster than previously available methods, and could be generalized for use on large portions of the light curves.

[ascl:1109.008]
Multipole Vectors: Decomposing Functions on a Sphere

We propose a novel representation of cosmic microwave anisotropy maps, where each multipole order l is represented by l unit vectors pointing in directions on the sky and an overall magnitude. These "multipole vectors and scalars" transform as vectors under rotations. Like the usual spherical harmonics, multipole vectors form an irreducible representation of the proper rotation group SO(3). However, they are related to the familiar spherical harmonic coefficients, alm, in a nonlinear way, and are therefore sensitive to different aspects of the CMB anisotropy. Nevertheless, it is straightforward to determine the multipole vectors for a given CMB map and we present an algorithm to compute them. Using the WMAP full-sky maps, we perform several tests of the hypothesis that the CMB anisotropy is statistically isotropic and Gaussian random. We find that the result from comparing the oriented area of planes defined by these vectors between multipole pairs 2<=l1!=l2<=8 is inconsistent with the isotropic Gaussian hypothesis at the 99.4% level for the ILC map and at 98.9% level for the cleaned map of Tegmark et al. A particular correlation is suggested between the l=3 and l=8 multipoles, as well as several other pairs. This effect is entirely different from the now familiar planarity and alignment of the quadrupole and octupole: while the aforementioned is fairly unlikely, the multipole vectors indicate correlations not expected in Gaussian random skies that make them unusually likely. The result persists after accounting for pixel noise and after assuming a residual 10% dust contamination in the cleaned WMAP map. While the definitive analysis of these results will require more work, we hope that multipole vectors will become a valuable tool for various cosmological tests, in particular those of cosmic isotropy.

[ascl:1109.006]
MultiNest: Efficient and Robust Bayesian Inference

We present further development and the first public release of our multimodal nested sampling algorithm, called MultiNest. This Bayesian inference tool calculates the evidence, with an associated error estimate, and produces posterior samples from distributions that may contain multiple modes and pronounced (curving) degeneracies in high dimensions. The developments presented here lead to further substantial improvements in sampling efficiency and robustness, as compared to the original algorithm presented in Feroz & Hobson (2008), which itself significantly outperformed existing MCMC techniques in a wide range of astrophysical inference problems. The accuracy and economy of the MultiNest algorithm is demonstrated by application to two toy problems and to a cosmological inference problem focusing on the extension of the vanilla $Lambda$CDM model to include spatial curvature and a varying equation of state for dark energy. The MultiNest software is fully parallelized using MPI and includes an interface to CosmoMC (ascl:1106.025). It will also be released as part of the SuperBayeS package (ascl:1109.007) for the analysis of supersymmetric theories of particle physics.

[ascl:1506.004]
multiband_LS: Multiband Lomb-Scargle Periodograms

The multiband periodogram is a general extension of the well-known Lomb-Scargle approach for detecting periodic signals in time-domain data. In addition to advantages of the Lomb-Scargle method such as treatment of non-uniform sampling and heteroscedastic errors, the multiband periodogram significantly improves period finding for randomly sampled multiband light curves (e.g., Pan-STARRS, DES and LSST). The light curves in each band are modeled as arbitrary truncated Fourier series, with the period and phase shared across all bands.

[ascl:1803.006]
MulensModel: Microlensing light curves modeling

MulensModel calculates light curves of microlensing events. Both single and binary lens events are modeled and various higher-order effects can be included: extended source (with limb-darkening), annual microlensing parallax, and satellite microlensing parallax. The code is object-oriented and written in Python3, and requires AstroPy (ascl:1304.002).

[ascl:1811.012]
muLAn: gravitational MICROlensing Analysis Software

muLAn analyzes and fits light curves of gravitational microlensing events. The code includes all classical microlensing models (for example, single and binary microlenses, ground- and space-based parallax effects, orbital motion, finite-source effects, and limb-darkening); these can be combined into several time intervals of the analyzed light curve. Minimization methods include an Affine-Invariant Ensemble Sampler to generate a multivariate proposal function while running several Markov Chain Monte Carlo (MCMC) chains, for the set of parameters which is chosen to be fit; non-fitting parameters can be either kept fixed or set on a grid defined by the user. Furthermore, the software offers a model-free option to align all data sets together and allow inspection the light curve before any modeling work. It also comes with many useful routines (export publication-quality figures, data formatting and cleaning) and state-of-the-art statistical tools.

Modeling results can be interpreted using an interactive html page which contains all information about the light curve model, caustics, source trajectory, best-fit parameters and chi-square. Parameters uncertainties and statistical properties (such as multi-modal features of the posterior density) can be assessed from correlation plots. The code is modular, allowing the addition of other computation or minimization routines by directly adding their Python files without modifying the main code. The software has been designed to be easy to use even for the newcomer in microlensing, with external, synthetic and self-explanatory setup files containing all important commands and option settings. The user may choose to launch the code through command line instructions, or to import muLAn within another Python project like any standard Python package.

[ascl:1710.011]
mTransport: Two-point-correlation function calculator

mTransport computes the 2-point-correlation function of the curvature and tensor perturbations in multifield models of inflation in the presence of a curved field space. It is a Mathematica implementation of the transport method which encompasses scenarios with violations of slow-roll conditions and turns of the trajectory in field space. It can be used for an arbitrary mass spectrum, including massive modes, particle production and models with quasi-single-field dynamics.

[ascl:1701.006]
MSWAVEF: Momentum-Space Wavefunctions

MSWAVEF calculates hydrogenic and non-hydrogenic momentum-space electronic wavefunctions. Such wavefunctions are often required to calculate various collision processes, such as excitation and line broadening cross sections. The hydrogenic functions are calculated using the standard analytical expressions. The non-hydrogenic functions are calculated within quantum defect theory according to the method of Hoang Binh and van Regemorter (1997). Required Hankel transforms have been determined analytically for angular momentum quantum numbers ranging from zero to 13 using Mathematica. Calculations for higher angular momentum quantum numbers are possible, but slow (since calculated numerically). The code is written in IDL.

[ascl:1709.007]
MSSC: Multi-Source Self-Calibration

Multi-Source Self-Calibration (MSSC) provides direction-dependent calibration to standard phase referencing. The code combines multiple faint sources detected within the primary beam to derive phase corrections. Each source has its CLEAN model divided into the visibilities which results in multiple point sources that are stacked in the uv plane to increase the S/N, thus permitting self-calibration. This process applies only to wide-field VLBI data sets that detect and image multiple sources within one epoch.

[ascl:1112.010]
MRS3D: 3D Spherical Wavelet Transform on the Sphere

Future cosmological surveys will provide 3D large scale structure maps with large sky coverage, for which a 3D Spherical Fourier-Bessel (SFB) analysis is natural. Wavelets are particularly well-suited to the analysis and denoising of cosmological data, but a spherical 3D isotropic wavelet transform does not currently exist to analyse spherical 3D data. We present a new fast Discrete Spherical Fourier-Bessel Transform (DSFBT) based on both a discrete Bessel Transform and the HEALPIX angular pixelisation scheme. We tested the 3D wavelet transform and as a toy-application, applied a denoising algorithm in wavelet space to the Virgo large box cosmological simulations and found we can successfully remove noise without much loss to the large scale structure. The new spherical 3D isotropic wavelet transform, called MRS3D, is ideally suited to analysing and denoising future 3D spherical cosmological surveys; it uses a novel discrete spherical Fourier-Bessel Transform. MRS3D is based on two packages, IDL and Healpix and can be used only if these two packages have been installed.

[ascl:1504.016]
MRrelation: Posterior predictive mass distribution

MRrelation calculates the posterior predictive mass distribution for an individual planet. The probabilistic mass-radius relationship (M-R relation) is evaluated within a Bayesian framework, which both quantifies this intrinsic dispersion and the uncertainties on the M-R relation parameters.

[ascl:1802.015]
mrpy: Renormalized generalized gamma distribution for HMF and galaxy ensemble properties comparisons

mrpy calculates the MRP parameterization of the Halo Mass Function. It calculates basic statistics of the truncated generalized gamma distribution (TGGD) with the TGGD class, including mean, mode, variance, skewness, pdf, and cdf. It generates MRP quantities with the MRP class, such as differential number counts and cumulative number counts, and offers various methods for generating normalizations. It can generate the MRP-based halo mass function as a function of physical parameters via the mrp_b13 function, and fit MRP parameters to data in the form of arbitrary curves and in the form of a sample of variates with the SimFit class. mrpy also calculates analytic hessians and jacobians at any point, and allows the user to alternate parameterizations of the same form via the reparameterize module.

[ascl:1809.015]
MrMoose: Multi-Resolution Multi-Object/Origin Spectral Energy distribution fitting procedure

MrMoose (Multi-Resolution Multi-Object/Origin Spectral Energy) fits user-defined models onto a set of multi-wavelength data using a Bayesian framework. The code can handle blended sources, large variation in resolution, and even upper limits consistently. It also generates a series of outputs allowing for an quick interpretation of the results. The code uses emcee (ascl:1303.002), and saves the emcee sampler object, thus allowing users to transfer the output to a personal graphical interface.

[ascl:1102.005]
MRLENS: Multi-Resolution methods for gravitational LENSing

The MRLENS package offers a new method for the reconstruction of weak lensing mass maps. It uses the multiscale entropy concept, which is based on wavelets, and the False Discovery Rate which allows us to derive robust detection levels in wavelet space. We show that this new restoration approach outperforms several standard techniques currently used for weak shear mass reconstruction. This method can also be used to separate E and B modes in the shear field, and thus test for the presence of residual systematic effects. We concentrate on large blind cosmic shear surveys, and illustrate our results using simulated shear maps derived from N-Body Lambda-CDM simulations with added noise corresponding to both ground-based and space-based observations.

[ascl:1212.003]
MPWide: Light-weight communication library for distributed computing

MPWide is a light-weight communication library for distributed computing. It is specifically developed to allow message passing over long-distance networks using path-specific optimizations. An early version of MPWide was used in the Gravitational Billion Body Project to allow simulations across multiple supercomputers.

[ascl:1106.022]
MPI-Defrost: Extension of Defrost to MPI-based Cluster Environment

MPI-Defrost extends Frolov’s Defrost to an MPI-based cluster environment. This version has been restricted to a single field. Restoring two-field support should be straightforward, but will require some code changes. Some output options may also not be fully supported under MPI.

This code was produced to support our own work, and has been made available for the benefit of anyone interested in either oscillon simulations or an MPI capable version of Defrost, and it is provided on an "as-is" basis. Andrei Frolov is the primary developer of Defrost and we thank him for placing his work under the GPL (GNU Public License), and thus allowing us to distribute this modified version.

[ascl:1208.014]
MPI-AMRVAC: MPI-Adaptive Mesh Refinement-Versatile Advection Code

van der Holst, Bar; Keppens, Rony; Meliani, Zakaria; Porth, Oliver; van Marle, Allard Jan; Delmont, Peter; Xia, Chun

MPI-AMRVAC is an MPI-parallelized Adaptive Mesh Refinement code, with some heritage (in the solver part) to the Versatile Advection Code or VAC, initiated by Gábor Tóth at the Astronomical Institute at Utrecht in November 1994, with help from Rony Keppens since 1996. Previous incarnations of the Adaptive Mesh Refinement version of VAC were of restricted use only, and have been used for basic research in AMR strategies, or for well-targeted applications. This MPI version uses a full octree block-based approach, and allows for general orthogonal coordinate systems. MPI-AMRVAC aims to advance any system of (primarily hyperbolic) partial differential equations by a number of different numerical schemes. The emphasis is on (near) conservation laws, with shock-dominated problems as a main research target. The actual equations are stored in separate modules, can be added if needed, and they can be selected by a simple configuration of the VACPP preprocessor. The dimensionality of the problem is also set through VACPP. The numerical schemes are able to handle discontinuities and smooth flows as well.

[ascl:1712.002]
MPI_XSTAR: MPI-based parallelization of XSTAR program

MPI_XSTAR parallelizes execution of multiple XSTAR runs using Message Passing Interface (MPI). XSTAR (ascl:9910.008), part of the HEASARC's HEAsoft (ascl:1408.004) package, calculates the physical conditions and emission spectra of ionized gases. MPI_XSTAR invokes XSTINITABLE from HEASoft to generate a job list of XSTAR commands for given physical parameters. The job list is used to make directories in ascending order, where each individual XSTAR is spawned on each processor and outputs are saved. HEASoft's XSTAR2TABLE program is invoked upon the contents of each directory in order to produce table model FITS files for spectroscopy analysis tools.

[ascl:1304.014]
MPgrafic: A parallel MPI version of Grafic-1

MPgrafic is a parallel MPI version of Grafic-1 which can produce large cosmological initial conditions on a cluster without requiring shared memory. The real Fourier transforms are carried in place using fftw while minimizing the amount of used memory (at the expense of performance) in the spirit of Grafic-1. The writing of the output file is also carried in parallel. In addition to the technical parallelization, it provides three extensions over Grafic-1:

- it can produce power spectra with baryon wiggles (DJ Eisenstein and W. Hu, Ap. J. 496);
- it has the optional ability to load a lower resolution noise map corresponding to the low frequency component which will fix the larger scale modes of the simulation (extra flag 0/1 at the end of the input process) in the spirit of Grafic-2;
- it can be used in conjunction with constrfield, which generates initial conditions phases from a list of local constraints on density, tidal field density gradient and velocity.

[ascl:1208.019]
MPFIT: Robust non-linear least squares curve fitting

These IDL routines provide a robust and relatively fast way to perform least-squares curve and surface fitting. The algorithms are translated from MINPACK-1, which is a rugged minimization routine found on Netlib, and distributed with permission. This algorithm is more desirable than CURVEFIT because it is generally more stable and less likely to crash than the brute-force approach taken by CURVEFIT, which is based upon Numerical Recipes.

[ascl:1611.003]
MPDAF: MUSE Python Data Analysis Framework

MPDAF, the MUSE Python Data Analysis Framework, provides tools to work with MUSE-specific data (for example, raw data and pixel tables), and with more general data such as spectra, images, and data cubes. Originally written to work with MUSE data, it can also be used for other data, such as that from the Hubble Space Telescope. MPDAF also provides MUSELET, a SExtractor-based tool to detect emission lines in a data cube, and a format to gather all the information on a source in one FITS file. MPDAF was developed and is maintained by CRAL (Centre de Recherche Astrophysique de Lyon).

[ascl:1710.006]
MOSFiT: Modular Open-Source Fitter for Transients

Guillochon, James; Nicholl, Matt; Villar, V. Ashley; Mockler, Brenna; Narayan, Gautham; Mandel, Kaisey S.; Berger, Edo; Williams, Peter K. G.

MOSFiT (Modular Open-Source Fitter for Transients) downloads transient datasets from open online catalogs (e.g., the Open Supernova Catalog), generates Monte Carlo ensembles of semi-analytical light curve fits to those datasets and their associated Bayesian parameter posteriors, and optionally delivers the fitting results back to those same catalogs to make them available to the rest of the community. MOSFiT helps bridge the gap between observations and theory in time-domain astronomy; in addition to making the application of existing models and creation of new models as simple as possible, MOSFiT yields statistically robust predictions for transient characteristics, with a standard output format that includes all the setup information necessary to reproduce a given result.

[ascl:1906.012]
Morpheus: Library to generate morphological semantic segmentation maps of astronomical images

Morpheus generates pixel level morphological classifications of astronomical sources by leveraging advances in deep learning to perform source detection, source segmentation, and morphological classification pixel-by-pixel via a semantic segmentation algorithm adopted from the field of computer vision. By utilizing morphological information about the flux of real astronomical sources during object detection, Morpheus shows resiliency to false positive identifications of sources.

[ascl:1906.013]
MORPHEUS: A 3D Eulerian Godunov MPI-OpenMP hydrodynamics code with multiple grid geometries

MORPHEUS (Manchester Omni-geometRical Program for Hydrodynamical EUlerian Simulations) is a 3D hydrodynamical code used to simulate astrophysical fluid flows. It has three different grid geometries (cartesian, spherical, and cylindrical) and uses a second-order Godunov method to solve the equations of hydrodynamics. Physical modules also include radiative cooling and gravity, and a hybrid MPI-OpenMP parallelization allows computations to be run on large-scale architectures. MORPHEUS is written in Fortran90 and does not require any libraries (apart from MPI) to run.

[ascl:1303.011]
MOPSIC: Extended Version of MOPSI

MOPSIC was created to analyze bolometer data but can be used for much more versatile tasks. It is an extension of MOPSI; this software had been merged with the command interpreter of GILDAS. For data reduction, MOPSIC uses a special method to calculate the chopped signal. This gives much better results than the straight difference of the signals obtained at both chopper positions. In addition there are also scripts to reduce pointings, skydips, and to calculate the RCPs (Receiver Channel Parameters) from calibration maps. MOPSIC offers a much broader range of applications including advanced planning functions for mapping and onoff observations, post-reduction data analysis and processing and even reduction of non-bolometer data (optical, IR, spectroscopy).

[ascl:1111.006]
MOPEX: MOsaicker and Point source EXtractor

MOPEX (MOsaicker and Point source EXtractor) is a package for reducing and analyzing imaging data, as well as MIPS SED data. MOPEX includes the point source extraction package, APEX.

MOPEX is designed to allow the user to:

- perform sophisticated background matching of individual data frames
- mosaic the individual frames downloaded from the Spitzer archive
- perform both temporal and spatial outlier rejection during mosaicking
- apply offline pointing refinement for MIPS data (refinement is already applied to IRAC data)
- perform source detection on the mosaics using APEX
- compute aperture photometry or PRF-fitting photometry for point sources
- perform interpolation, coaddition, and spectrum extraction of MIPS SED images.

[ascl:1308.018]
MoogStokes: Zeeman polarized radiative transfer

MOOGStokes is a version of the MOOG one-dimensional local thermodynamic equilibrium radiative transfer code that incorporates a Stokes vector treatment of polarized radiation through a magnetic medium. It consists of three complementary programs that together can synthesize the disk-averaged emergent spectrum of a star with a magnetic field. The MOOGStokes package synthesizes emergent spectra of stars with magnetic fields in a familiar computational framework and produces disk-averaged spectra for all Stokes vectors ( I, Q, U, V ), normalized by the continuum.

[ascl:1202.009]
MOOG: LTE line analysis and spectrum synthesis

MOOG performs a variety of LTE line analysis and spectrum synthesis tasks. The typical use of MOOG is to assist in the determination of the chemical composition of a star. The basic equations of LTE stellar line analysis are followed. The coding is in various subroutines that are called from a few driver routines; these routines are written in standard FORTRAN. The standard MOOG version has been developed on unix, linux and macintosh computers.

One of the chief assets of MOOG is its ability to do on-line graphics. The plotting commands are given within the FORTRAN code. MOOG uses the graphics package SM, chosen for its ease of implementation in FORTRAN codes. Plotting calls are concentrated in just a few routines, and it should be possible for users of other graphics packages to substitute other appropriate FORTRAN commands.

[ascl:1805.027]
MontePython 3: Parameter inference code for cosmology

MontePython 3 provides numerous ways to explore parameter space using Monte Carlo Markov Chain (MCMC) sampling, including Metropolis-Hastings, Nested Sampling, Cosmo Hammer, and a Fisher sampling method. This improved version of the Monte Python (ascl:1307.002) parameter inference code for cosmology offers new ingredients that improve the performance of Metropolis-Hastings sampling, speeding up convergence and offering significant time improvement in difficult runs. Additional likelihoods and plotting options are available, as are post-processing algorithms such as Importance Sampling and Adding Derived Parameter.

[ascl:1307.002]
Monte Python: Monte Carlo code for CLASS in Python

Monte Python is a parameter inference code which combines the flexibility of the python language and the robustness of the cosmological code CLASS into a simple and easy to manipulate Monte Carlo Markov Chain code.

This version has been archived and replaced by MontePython 3 (ascl:1805.027).

[ascl:1502.006]
Montblanc: GPU accelerated Radio Interferometer Measurement Equations in support of Bayesian Inference for Radio Observations

Montblanc, written in Python, is a GPU implementation of the Radio interferometer measurement equation (RIME) in support of the Bayesian inference for radio observations (BIRO) technique. The parameter space that BIRO explores results in tens of thousands of computationally expensive RIME evaluations before reduction to a single *X ^{2}* value. The RIME is calculated over four dimensions, time, baseline, channel and source and the values in this 4D space can be independently calculated; therefore, the RIME is particularly amenable to a parallel implementation accelerated by Graphics Programming Units (GPUs). Montblanc is implemented for NVIDIA's CUDA architecture and outperforms MeqTrees (ascl:1209.010) and OSKAR.

[ascl:1010.036]
Montage: An Astronomical Image Mosaicking Toolkit

Jacob, Joseph C.; Katz, Daniel S.; Berriman, G. Bruce; Good, John; Laity, Anastasia C.; Deelman, Ewa; Kesselman, Carl; Singh, Gurmeet; Su, Mei-Hui; Prince, Thomas A.; Williams, Roy

Montage is an open source code toolkit for assembling Flexible Image Transport System (FITS) images into custom mosaics. It runs on all common Linux/Unix platforms, on desktops, clusters and computational grids, and supports all World Coordinate System (WCS) projections and common coordinate systems. Montage preserves spatial and calibration fidelity of input images, processes 40 million pixels in up to 32 minutes on 128 nodes on a Linux cluster, and provides independent engines for analyzing the geometry of images on the sky, re-projecting images, rectifying background emission to a common level, and co-adding images. It offers convenient tools for managing and manipulating large image files.

[ascl:1206.004]
MOLSCAT: MOLecular SCATtering

MOLSCAT is a FORTRAN code for quantum mechanical (coupled channel) solution of the nonreactive molecular scattering problem and was developed to obtain collision rates for molecules in the interstellar gas which are needed to understand microwave and infrared astronomical observations. The code is implemented for various types of collision partners. In addition to the essentially exact close coupling method several approximate methods, including the Coupled States and Infinite Order Sudden approximations, are provided.

[ascl:1907.012]
molly: 1D astronomical spectra analyzer

molly analyzes 1D astronomical spectra. Its prime purpose is for handling large numbers of similar spectra (*e.g.,* time series spectroscopy), but it contains many of the standard operations used for normal spectrum analysis as well. It overlaps with the various similar programs such as dipso (ascl:1405.016) and has strengths (particularly for time series spectra) and weaknesses compared to them.

[ascl:1212.004]
MOLIERE-5: Forward and inversion model for sub-mm wavelengths

MOLIERE-5 (Microwave Observation LIne Estimation and REtrieval) is a versatile forward and inversion model for the millimeter and submillimeter wavelengths range and includes an inversion model. The MOLIERE-5 forward model includes modules for the calculation of absorption coefficients, radiative transfer, and instrumental characteristics. The radiative transfer model is supplemented by a sensitivity module for estimating the contribution to the spectrum of each catalog line at its center frequency enabling the model to effectively filter for small spectral lines. The instrument model consists of several independent modules, including the calculation of the convolution of spectra and weighting functions with the spectrometer response functions. The instrument module also provides several options for modeling of frequency-switched observations. The MOLIERE-5 inversion model calculates linear Optimal Estimation, a least-squares retrieval method which uses statistical apriori knowledge on the retrieved parameters for the regularization of ill-posed inversion problems and computes diagnostics such as the measurement and smoothing error covariance matrices along with contribution and averaging kernel functions.

[ascl:1501.013]
Molecfit: Telluric absorption correction tool

Smette, A.; Kausch, W; Sana, H; Noll, S.; Horst, H.; Kimeswenger, S.; Barden, M; Szyszka, C.; Jones, A. M.; Gallene, A.; Vinther, J.; Ballester, P.; Kerber, F.

Molecfit corrects astronomical observations for atmospheric absorption features based on fitting synthetic transmission spectra to the astronomical data, which saves a significant amount of valuable telescope time and increases the instrumental efficiency. Molecfit can also estimate molecular abundances, especially the water vapor content of the Earth’s atmosphere. The tool can be run from a command-line or more conveniently through a GUI.

[ascl:1109.023]
MOKA: A New Tool for Strong Lensing Studies

MOKA simulates the gravitational lensing signal from cluster-sized haloes. This algorithm implements recent results from numerical simulations to create realistic lenses with properties independent of numerical resolution and can be used for studies of the strong lensing cross section in dependence of halo structure.

[ascl:1010.009]
ModeCode: Bayesian Parameter Estimation for Inflation

ModeCode is a publicly available code that computes the primordial scalar and tensor power spectra for single field inflationary models. ModeCode solves the inflationary mode equations numerically, avoiding the slow roll approximation. It provides an efficient and robust numerical evaluation of the inflationary perturbation spectrum, and allows the free parameters in the inflationary potential to be estimated within an MCMC computation. ModeCode also allows the estimation of reheating uncertainties once a potential has been specified. It is interfaced with CAMB and CosmoMC to compute cosmic microwave background angular power spectra and perform likelihood analysis and parameter estimation. It can be run as a standalone code as well. Errors in the results from ModeCode contribute negligibly to the error budget for analyses of data from Planck or other next generation experiments.

[ascl:1110.010]
MOCASSIN: MOnte CArlo SimulationS of Ionized Nebulae

MOCASSIN is a fully 3D or 2D photoionisation and dust radiative transfer code which employs a Monte Carlo approach to the transfer of radiation through media of arbitrary geometry and density distribution. Written in Fortran, it was originally developed for the modelling of photoionised regions like HII regions and planetary nebulae and has since expanded and been applied to a variety of astrophysical problems, including modelling clumpy dusty supernova envelopes, star forming galaxies, protoplanetary disks and inner shell fluorence emission in the photospheres of stars and disk atmospheres. The code can deal with arbitrary Cartesian grids of variable resolution, it has successfully been used to model complex density fields from SPH calculations and can deal with ionising radiation extending from Lyman edge to the X-ray. The dust and gas microphysics is fully coupled both in the radiation transfer and in the thermal balance.

[ascl:1905.005]
MMIRS-DRP: MMIRS Data Reduction Pipeline

The MMIRS data reduction pipeline provides complete and flexible data reduction for long-slit and multi-slit spectroscopic observations collected using the MMT and Magellan Infrared Spectrograph (MMIRS). Written in IDL, it offers sky subtraction, correction for telluric absorpition, and is fast enough to permit real-time data reduction for quality control.