I'll add a little to Arne's note: One of my CCD-newbie lessons is that any star within 2-3 magnitudes of your limit of detection - the smudges that maybe are or maybe aren't stars - is going to give you lousy statistics. So don't use them for anything other than field identification, certainly not as standards, or your data plots are going to look like an unmowed lawn. === Regards, Lew - Visit http://home.pacbell.net/cookl _________________________________________________________ Do You Yahoo!? Get your free @yahoo.com address at http://mail.yahoo.com