From: BailyHill Date: Wed, 15 Mar 2006 20:05:28 EST Date: Wed, 15 Mar 2006 20:05:28 EST To: huziak Hello; What Richard and Michael suggest is also what I have been doing for the past couple years. I usually calculate the std dev of 10 observations of a singe star. Clear Skies Gary Walker CCD Chair _______________________________________________