Stellarium Desktop Planetarium
Stellarium is a fantastic piece of freeware used by many astronomy clubs and planetariums. It’s a free open source planetarium for your computer. It shows a realistic sky in 3D, just like what you see with the naked eye, binoculars or a telescope.
Registax Imaging Software
Registax is a free image stacking and processing program for astrophotograhers . Widely used by both armature and professional astronomers worldwide.
DeepSkyStacker is a freeware for astrophotographers that simplifies all the pre-processing steps of deep sky pictures.
Simple post-stacking processes to quickly view the final result.
Saving the resulting image to a TIFF or FITS file (16 or 32 bit)