Re: Reprocessing Production

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

Date: Fri, 21 Sep 2007 22:40:24 +0200
From: Paul Bartholdi <Paul.Bartholdi@obs.unige.ch>
To: Tass Mailing List <tass@mail.alembic.net>
Subject: Re: Reprocessing Production

Dear Michael,

On 9/21/07, Tass Mailing List <tass@mail.alembic.net> wrote:
>
>
> 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


I had a good experience with old fashion photomultiplier 1D photometry, but
indeed no one with 2D detectors. But, as I understand, the technic
developped by Alard and Lupton assumes a non uniform PSF, both in the
detector plane and in time from images to images. It is also intended for
automatic processing. Can it deal with the Tass system, this I dont know at
all, but thought it could be worth reading the article. I dont know either
why it is not better known. If you get any result, either good or bad,
please keep me informed. The nice things in astronomy is that you can
reprocess the data as long you keep the original available.

Best regards,     Paul

PS By the way, it is (was ?) available in ArXiv: astro-ph/9712287