The ERFA C library contains key algorithms for astronomy, and is based on the SOFA library published by the IAU.

pyHalo renders full mass distributions for substructure lensing simulations with gravitational lensing software package lenstronomy. The main purpose of the code is to quickly render full populations of dark matter subhalos and line of sight halos for gravitational lensing simulations. It also transltes halo properties (mass, concentration, redshift, etc) into angular units for lensing computations with lenstronomy.

Colossus is a Python toolkit for calculations pertaining to cosmology, the large-scale structure of the universe, and the properties of dark matter halos.

This package provides general tools for astronomical time series in Python.

This package provides an astronomical Python package with image processing functions: xyxymatch, geomap.

stsci.imagestats is a package designed to compute various statistics on image data using sigma-clipping iterations. It is designed to replicate core behaviour of the IRAF's imstatistics task.

PetroFit is a package for calculating Petrosian properties, such as radii and concentration indices, as well as fitting galaxy light profiles. In particular, PetroFit includes tools for performing accurate photometry, segmentations, Petrosian profiling, and Sérsic fitting.

Baseband is a package for reading and writing VLBI and other radio baseband files, with the aim of simplifying and streamlining data conversion and standardization.

This package implements a funtionality for hierarchical analysis of strong lensing systems to infer lens properties and cosmological parameters simultaneously. It allows to fit lenses with measured time delays, imaging information, kinematics constraints and standardizable magnifications with parameters described on the ensemble level.

Weightwatcher is a program hat 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.

This package provides a replacement for IRAF STSDAS SYNPHOT and ASTROLIB PYSYNPHOT, utilizing Astropy and covering the non-instrument specific portions of the old packages.

PyEphem provides an ephem Python package for performing high-precision astronomy computations.

The name ephem is short for the word ephemeris, which is the traditional term for a table giving the position of a planet, asteroid, or comet for a series of dates.

The concept of the pvextractor package is simple - given a path defined in sky coordinates, and a spectral cube, extract a slice of the cube along that path, and along the spectral axis, producing a position-velocity or position-frequency slice.

The glue-astronomy plugin for glue provides a collection of astronomy-specific functionality

Ginga is a toolkit designed for building viewers for scientific image data in Python, visualizing 2D pixel data in numpy arrays. It can view astronomical data such as contained in files based on the FITS (Flexible Image Transport System) file format. It is written and is maintained by software engineers at the National Astronomical Observatory of Japan (NAOJ), the Space Telescope Science Institute (STScI), and other contributing entities.

The Ginga toolkit centers around an image display object which supports zooming and panning, color and intensity mapping, a choice of several automatic cut levels algorithms and canvases for plotting scalable geometric forms. In addition to this widget, a general purpose "reference" FITS viewer is provided, based on a plugin framework. A fairly complete set of standard plugins are provided for features that we expect from a modern FITS viewer: panning and zooming windows, star catalog access, cuts, star pick/FWHM, thumbnails, etc.

qfits is a C library giving access to FITS file internals, both for reading and writing.

Astroquery is a package that contains a collection of tools to access online Astronomical data. Each web service has its own sub-package.

This package provides a range of colormaps designed for scientific use with Matplotlib. It includes perceptually uniform sequential colormaps such as abre, dusk, kepl, and octarine, as well as monochromatic sequential colormaps like blue, green, and red, and others (algae, pastel, and xray).

Portable library and tools for manipulating extended attributes.

Libzita-resampler is a C++ library for resampling audio signals. It is designed to be used within a real-time processing context, to be fast, and to provide high-quality sample rate conversion.

The LV2 Toolkit (LVTK) contains libraries that wrap the LV2 C API and extensions into easy to use C++ classes. It is the successor of lv2-c++-tools.

Audacity is a multi-track audio editor designed for recording, playing and editing digital audio. It features digital effects and spectrum analysis tools.

r128gain is a multi platform command line tool to scan your audio files and tag them with loudness metadata (ReplayGain v2 or Opus R128 gain format), to allow playback of several tracks or albums at a similar loudness level. r128gain can also be used as a Python module from other Python projects to scan and/or tag audio files.

cli-visualizer displays fast-Fourier transforms (FFTs) of the sound being played, as well as other graphical representations.