For reasons unknown, I did not get a complete copy of the SeeSat-Digest 96/228 in which Geoff Chester's response and correction to my post on this subject appeared, only now learning of my mistake. In my original post, I had indicated, after working out the exposure formula provided in Barry Gordon's book, "Astrophotography" that for a mag. 10 geosync satellite, using 200 ASA/ISO film and a C-8 at prime focus, the resulting exposure time was "2 seconds." Geoff correctly pointed out that should have been "2 minutes." This, obviously, was no small error and I thank him for catching that. Jim Cook (CmdrJaycee@aol.com)