Results 701-750 of 1981 (1948 ASCL, 33 submitted)

[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.

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