Stellarium is a free GPL software which renders realistic skies in real time with OpenGL. It is available for Linux/Unix, Windows and macOS. With Stellarium, you really see what you can see with your eyes, binoculars or a small telescope.
This is the official GitHub repository for OpenSpace: an open source astrovisualization project. For instructions on how to build and run OpenSpace, see the Getting Started Guides on the wiki page at http://wiki.openspaceproject.com
Core package to analyze gravitational-wave data, find signals, and study their parameters. This package was used in the first direct detection of gravitational waves (GW150914), and is used in the ongoing analysis of LIGO/Virgo data.