Re: Reprocessing Production

[Tass Mailing List <tass@mail.alembic.net>]

Date: Fri, 21 Sep 2007 15:16:57 -0400
From: Michael Richmond <richmond@stupendous.cis.rit.edu>
To: tass@tass-survey.org
Cc: richmond@stupendous.cis.rit.edu
Subject: Re: Reprocessing Production


  Paul Bartholdi brought up a good idea:

> I wonder if the article by Alard and Lupton on optimal image substraction is
> known in this group. It deals with photometry in crowded fields. If not, you
> can take a copy on my site:
>
>      http://obswww.unige.ch/~bartho/Allard_Lupton.ps.gz .

  The image subtracting technique _can_ yield much better results than
the simple aperture photometry in the current pipeline, but I don't
think it will work in our particular case.  The problem is that the
PSF varies very strongly across the wide TASS field of view.
In order to use the image subtraction technique, one must have a
very good model of the PSF at every point in an image.  Alas,
we don't have such a good model.

  I suspect -- but don't know for sure -- that the PSF changes
signficantly from night to night, too, which would make the
application of this technique in some automated way even harder.

  Not impossible, perhaps, if someone has access to an entire night's
images, but not easy.

                 Michael