free astronomy software

C2A

C2A is a planetarium software developed by Philippe Deverchère which you can use for building and viewing of stellar fields. With this program you can use it to access several catalogues for use in astrometry, and it also works well as a general purpose planetarium program.

Cartes du Ciel

Cartes du Ciel (or Sky Chart) is an astronomy program. Created by Patrick Chevalley, it is a powerful planetarium with features similar to commercially available software. Cartes du Ciel precisely shows the placements of stars. Information on several stars are also provided. But it offers a lot more. Cartes du Ciel can also give you information on planets, asteroids, nebulae, galaxies and comets. The software supports many catalogs including Guide Star and Tycho. Other catalogs can be used so you can see thousands of stars.