Links Recommended by Spica

To know if some artificial satellites are visible :
http://www.gsoc.dlr.de/satvis/

The Astro-club of the Ecole Nationale Supérieure des Mines de Saint-Etienne
http://messel.emse.fr/~astro

XEphem page, one of the best astronomical software for UNIX and LINUX
http://www.ClearSkyInstitute.com