Results 801-850 of 2402 (2363 ASCL, 39 submitted)

[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:2006.018]
Powderday: Dust radiative transfer package

Narayanan, Desika; Turk, Matthew J.; Robitaille, Thomas; Kelly, Ashley J.; Connor McClellan, B.; Sharma, Ray S.; Garg, Prerak; Abruzzo, Matthew; Choi, Ena; Conroy, Charlie; Johnson, Benjamin D.; Kimock, Benjamin; Li, Qi; Lovell, Christopher C.; Lower, Sidney; Privon, George C.; Roberts, Jonathan; Sethuram, Snigdaa; Snyder, Gregory F.; Thompson, Robert; Wise, John H.

The dust radiative transfer software Powderday interfaces with galaxy formation simulations to produce spectral energy distributions and images. The code uses fsps (ascl:1010.043) and its Python bindings python-fsps for stellar SEDs, Hyperion (ascl:1207.004) for dust radiative transfer, and works with a variety of packages, including Arepo (ascl:1909.010), Changa (ascl:1105.005), Gasoline (ascl:1710.019), and Gizmo (ascl:1410.003); threaded throughout is yt (ascl:1011.022).

[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:2003.006]
PORTAL: POlarized Radiative Transfer Adapted to Lines

PORTAL (POlarized Radiative Transfer Adapted to Lines), a 3D polarized radiative transfer code, simulates the emergence of polarization in the emission of atomic or molecular (sub-)millimeter lines. Written in Fortran90, PORTAL can be used in standalone mode or can process the output of other 3D radiative transfer codes

[ascl:1912.008]
PopSyCLE: Population Synthesis for Compact object Lensing Events

PopSyCLE performs compact object population synthesis while taking photometric and astrometric microlensing effects into consideration. It uses Galaxia (ascl:1101.007) to produces a synthetic survey, injects compact objects into the resulting survey, and then produces a list of microlensing events, enabling the discovery of black holes with microlensing. It can be used to examine historical microlensing events from photometric surveys to statistically constrain the abundance of black holes in our galaxy, and to forward model microlensing survey results to constrain, for example, the properties of compact objects, Galactic structure, and the initial-final mass relation.

[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:2007.006]
PoPE: Population Profile Estimator

PoPE (Population Profile Estimator) analyzes spatial distribution or internal spatial structure problems of samples of astronomical systems. This population-based Bayesian inference model uses the conditional statistics of spatial profile of multiple observables assuming the individual observations are measured with errors of varying magnitude. Assuming the conditional statistics of the observables can be described with a multivariate normal distribution, the model reduces to the conditional average profile and conditional covariance between all observables. The method consists of two steps: (1) reconstructing the average profile using non-parametric regression with Gaussian Processes and (2) estimating the property profiles covariance given a set of independent variable. PoPE is computationally efficient and capable of inferring average profiles of a population from noisy measurements without stacking and binning nor parameterizing the shape of the average profile.

[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:2012.016]
Pomegranate: Probabilistic model builder

Pomegranate builds probabilistic models in Python that is implemented in Cython for speed. The code merges the easy-to-use API of scikit-learn with the modularity of probabilistic modeling, including general mixture and hidden Markov models and Bayesian networks, to allow users to specify complicated models without the need to be concerned about implementation details. The models are built from the ground up and natively support features such as multi-threaded parallelism and out-of-core processing.

[ascl:1912.001]
Polyspectrum: Computing polyspectra using an FFT estimator

Polyspectrum computes the polyspectrum from 3D grids using a fast Fourier transformation (FFT) estimator. The code, written in C and MPI-parallelized, support the computation of power- and bispectra; it also supports higher-order polyspectra, but streamlining the input data is required.

[ascl:2007.009]
polyMV: Multipolar coefficients converter

polyMV converts multipolar coefficients (alms in healpix order) into Multipole Vectors (MVs) and also Fréchet Vectors (FVs) given a specific multipole. The code uses MPSolve (ascl:2007.008) and is order of magnitudes faster than other existing public codes at high multipoles.

[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).

[submitted]
polgraw-allsky

Astone, Pia; Bejger, Michał; Bolek, Jan; Ciecieląg, Paweł; Dorosh, Orest; Garus, Aleksander; Królak, Andrzej; Nagy-Egri, Máté Ferenc; Piętka, Maciej; Pisarski, Andrzej; Poghosyan, Gevorg; Sieniawska, Magdalena; Skrzypiec, Rafał

All-sky almost-monochromatic gravitational-wave pipeline (Polgraw group)

[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:2011.025]
PNICER: Extinction estimator

PNICER estimates extinction for individual sources and creates extinction maps using unsupervised machine learning algorithms. Extinction towards single sources is determined by fitting Gaussian Mixture Models along the extinction vector to (extinction-free) control field observations. PNICER also offers access to the well-established NICER technique in a simple unified interface and is capable of building extinction maps including the NICEST correction for cloud substructure.

[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 (ascl:1102.008). 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, focusing on astrophysical applications. It calculates extra quantities on the particles, calculates and plots radial profiles, accesses subsets of particles, and provides visualization of any quantity defined on the particles via kernel density estimation. 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:1911.007]
planetplanet: General photodynamical code for exoplanet light curves

planetplanet models exoplanet transits, secondary eclipses, phase curves, and exomoons, as well as eclipsing binaries, circumbinary planets, and more. The code was originally developed to model planet-planet occultation (PPO) light curves for the TRAPPIST-1 system, but it is generally applicable to any exoplanet system. During a PPO, a planet occults (transits) the disk of another planet in the same planetary system, blocking its thermal (and reflected) light, which can be measured photometrically by a distant observer. planetplanet is coded in C and wrapped in a user-friendly Python interface.

[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:2010.009]
plancklens: Planck 2018 lensing pipeline

plancklens contains most of Planck 2018 CMB lensing pipeline and makes it possible to reproduce the published map and band-powers. Some numerical parts are written in Fortran, and portions of it (structure and code) have been directly adapted from pre-existing work by Duncan Hanson. The lensed CMB skies is produced by the stand-alone package lenspyx (ascl:2010.010).

[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:1911.001]
PLAN: A Clump-finder for Planetesimal Formation Simulations

PLAN (PLanetesimal ANalyzer) identifies and characterizes planetesimals produced in numerical simulations of the Streaming Instability that includes particle self-gravity with code Athena (ascl:1010.014). PLAN works with the 3D particle output of Athena and finds gravitationally bound clumps robustly and efficiently. PLAN — written in C++ with OpenMP/MPI — is massively parallelized, memory-efficient, and scalable to analyze billions of particles and multiple snapshots simultaneously. The approach of PLAN is based on the dark matter halo finder HOP (ascl:1102.019), but with many customizations for planetesimal formation. PLAN can be easily adapted to analyze other object formation simulations that use Lagrangian particles (e.g., Athena++ simulations). PLAN is also equipped with a toolkit to analyze the grid-based hydro data (VTK dumps of primitive variables) from Athena, which requires the Boost MultiDimensional Array Library.

[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:2010.014]
Pix2Prof: Deep learning for textraction of useful sequential information from galaxy imagery

Pix2Prof produces a surface brightness profile from an unprocessed galaxy image from the SDSS in either the g, r, or i bands. It is fast, and given suitable training data, Pix2Prof can be retrained to produce any galaxy profile from any galaxy image.

[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.

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