Return to Home Page
I don't think the C-offset is the default in AIP4WIN. The default setting for C tracking will IMO be able to process timeseries taken in altaz. It will even allow to hook V or K on a moving comet on the images to do photometry on it. The problem with the default setting is that the C selection/centering is quite nervous as if the aperture wants to jump away from the selected C star. However there is no problem if C is somewhat isolated (more than 20 -30 (?) arcsec away from any other star of similar or slightly fainter brightness). Multiple image photometry in manual mode (pe for faint stars) is not working well and therefore not accurate and time consuming. If I remember well, it doesn't work in C-offset at all.. Berto >>> Taichi Kato <tkato@kusastro.kyoto-u.ac.jp> 07/08/03 12:15PM >>> Re: Software problem in time-series photometry > The centering error on faint stars that Taichi-san mentions > in AIP4WIN can be avoided altogether by doing photometry as > C-Offset where the comparison xtar (presumably bright > enough to be reliably centered on all images and the > variable and check are not centered except on the first > image of the set and the apertures are rigidly placed in > the same location relative to the comparison star. Thanks, Lew! Is everyone using this option? (In precise photometry, I regard this option as a default -- we use multiple stars to compensate a small-order deviation from a constant offset. With an Alt-Az mount, one also need to incorporate image rotation). Use this option whenever applicable. If everyone uses this option and still gets unrealistic depressions in the light curve or other unusual features, we should search for a different explanation -- in any case, this would provide a critical test for the software. Regards, Taichi Kato -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. Mailscanner thanks transtec Computers for their support.
Return to the Powerful Daisaku
vsnet-adm@kusastro.kyoto-u.ac.jp
