#Why I won't upgrade
I am aware of your package and its almost at the "buy threshold". With the
addition of a star database it would become a must-have. Check out the
Astronomy forum, there is a nice shareware planetarium program for Windows (two
files: SKYMPA.ZIP & SKYMPB.ZIP). In it he mentions a bit about where the
display algorithms are from and where the database for star positions are from.