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From Arto.Oksanen@tietoenator.com Wed Jul 9 02:41:01 2003 Delivered-To: tkato@kusastro.kyoto-u.ac.jp From: Arto.Oksanen@tietoenator.com To: tkato@kusastro.kyoto-u.ac.jp Subject: Re: Software problem in time-series photometry Date: Tue, 8 Jul 2003 20:31:28 +0300 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable X-Virus-Scanned: by AMaViS perl-11 Content-Length: 2292 Dear Taichi, Yes, the C Offset is our default setting at Nyrola and it gives the = best results. =20 I would still vote for using AIP4Win, as it is so easy and fast to use. Another option is use IRAF, but it is very time consuming and = measurements will backlog especially if there is several observing nights in a row. = With AIP4Win we are able to send the results a few minutes after the last observation.=20 I have made tests with IRAF and AIP4Win using the same image sets and = the results have been quite close allways. Maybe you could copy one dataset = that produces wrong results for me to re-analyse? I can run it through = IRAF/PHOT too. best regards, arto -- Arto Oksanen mailto:arto.oksanen@jklsirius.fi Jyvaskylan Sirius ry, Kyllikinkatu 1, FIN-40100 Jyv=E4skyl=E4, Finland=20 Tel: +358-40-5659438 Fax: +358-14-4157803 Nyrola Observatory http://vsnet.ursa.fi/sirius/nytt/nytt_info.html=20 -----Original Message----- From: Taichi Kato [mailto:tkato@kusastro.kyoto-u.ac.jp]=20 Sent: 8. hein=E4kuuta 2003 13:16 To: vsnet-campaign-ccd-discussion@ooruri.kusastro.kyoto-u.ac.jp; vsnet-chat@ooruri.kusastro.kyoto-u.ac.jp Subject: =C4vsnet-campaign-ccd-discussion 57=C5 Re: Software problem in time-series photometry 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
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