A planetarium software that shows a 3D simulation of the night sky
Stellarium renders 3D photo-realistic skies in real time with OpenGL. It displays stars, constellations, planets, nebulae and others things like ground, landscape, atmosphere, etc.
SkyChart is a software to draw chart of the night sky for the amateur astronomer from a bunch of stars and nebulae catalogs. See main web page for full download. This software is part of a full suite for astronomical observation: https://sourceforge.net/projects/ccdciel/ https://sourceforge.net/projects/indistarter/ https://sourceforge.net/projects/eqmodgui/ Requirement: https://sourceforge.net/projects/libpasastro/ See also: https://sourceforge.net/projects/indi/
Real-time 3D visualization of space
Celestia is an application for real-time 3D visualization of space, with a detailed model of the solar system, over 100,000 stars, more than 10,000 galaxies, and an extension mechanism for adding more objects.
Java based astronomical logging software which stores it's data in a free and open XML based format (OpenAstronomyLog).
Jewish prayer times
Android application that displays list of halachic/halakhic times for Jewish prayers (zmanim and zmanei tefillot).