Re: Time for Software

[Andrew Bennett <andrew.bennett@ns.sympatico.ca>]

On Wed, 2 Aug 2000 13:38:06 -0400 , "Gutzwiller, Michael"
<mgutzwiller@lanvision.com> wrote:

>I'll take a whack at the pipeline stages:
>
>Stage                        Input                 Output
>
>Camera Calibration           Photons               Dark Field, Flat Field
>Image Acquisition            Photons               FITS Image
>Star List Generation         FITS Image,           Star List (x,y)
>                             Dark Field,
>                             Flat Field 
>Registration to Catalog      Star List (x,y)       Star List (ra,dec)
>Color Calibration            Star List (x,y)       Star List (ra,dec)
>Insert to database           Star List (ra, dec)   Observations database

I am working on a more complicated StarList Generation/Registration
to catalog process. In the above format it looks like:
Stage                     Input                 Output
Clean Image               FITS Image,           Clean Image
                          Dark Field,
                          Flat Field,
                          (Hot Pixel list?)
Preliminary Star List     Clean Image,          Star List (x,y)
                                                Bright Star List
                                                Other List (CR's etc)
Prelim Registration       Star List (x,y),      Prelim Astrometry,
                          Catalog               Prelim Photometry
Select List for PSF       Star List,            Select list
                          Catalog
Full List                 Star Lists,           Full List (x,y)
                          Catalog,
                          Data Base
PSF update                Clean Image,          PSF estimate
                          Select List
Fit Stars                 Clean Image,          Full List, x,y,A
                          Full List,
                          PSF estimate
Registration              Full List x,y,        Final Astrometry,
                          Catalog               Photometry,
                                                Full List, RA,DEC,MAG

This degree of complexity allows one to look at stars which
would otherwise be below the detection threshold on some images,
thus eliminating one of the major shortcomings of TENXCAT.

There is nothing sacred about the order of events ... one
should probably work all the way through to final astrometry
and then go back and do the catalog merge stuff and produce
the final star list. The above precis is just the way it grew.

Even if you don't believe in fitted PSF's etc, the MK IV
processing should include the step of merging previously
seen objects into the finding list. This requires the
catalog matching step.

I am currently getting below 1 arc sec probable error for the
preliminary matching and around 0.3 arc sec for the final
match, using Tycho2.

Andrew Bennett, Avondale Vineyard, Nova Scotia, Canada.