I am writing a script right now which at one point needs to calculate RA and Dec. There is a telescope pointing directly upwards(altitude=90 deg) and I know where the telescope is located and the time when I get an event. When the telescope sees something my script reads some info and I need to convert where it saw something to RA and Dec. It's been forever since I had a class on how to do this conversion, and I don't have my book anymore. Any chance someone can point me to a good link that can help me out with an equation for this conversion? I don't really remember enough to derive this myself unfortunately.