Hello Robert; Both the double star data and the deep sky data are public domain. However, we do ask that if you use them in a product for which you charge a fee, make a modest contribution to the International Dark Sky Association in the name of SAC. So, what are you planning to do with the data? I hope it is something new and exciting. The data is rather old at this point and one of these days I am going to get the time to update it, but I have just had too much on my plate recently to take it on. Besides, double stars are just one of those things that people nowadays don't pay much attention too. Too bad, lots of fun doubles to see. Clear Skies; Steve Coe Author "Deep Sky Observing--The Astronomical Tourist" Saguaro Astronomy Club website www.saguaroastro.org