[News] Some issues
Luiz DaCosta
ldacosta at eso.org
Thu Sep 11 14:58:52 CEST 2003
Mark
I wonder if you would be interested in coming to ESO and getting a demo
from B. Vandame using the C-library only for the same data which we
could ftp
to ESO - I would be very interested
Luiz
Dr. Mark Neeser wrote:
>Hello All,
>
>As a test of data reduction routines (astro-wise vs. Bonn pipeline vs.
>IRAF) we have immersed ourselves (primarily Jan Snigula and
>Yuliana Goranova) in the astro-wise pipeline using our WFI data.
>
>Here some results/comments:
>
>- Dataset used for testing: WiFI- images taken over 6 nights
> (approx. 50GB).
>
> Time for testreduction: approx. 1 week (most of the delays were caused
> by unannounced pipeline changes occurring during the reduction.
>
>Details:
>
>- COSMICFILTER:
> We tried to implement our cosmic filtering routine (cosmicfits from
> Claus Goessl) in the pipeline. This attempt failed, due to the
> current handling of bad columns/pixels in the images and the
> existance of negative pixel values. The latter problem can be
> circumvented in the program call, but the bad columns/pixels would
> need to be replaced (PRIOR to executing our cosmic filter routine) with
> a well defined NaN value, e.g. 0. Essentially, our cosmic filter
> routine treats the bad columns as cosmic rays and spends an inordinate
> amount of time trying to detect/correct them. It would be easy to
> mask these as NaN's prior to running "cosmicfits".
>
>- BAD COLUMNS:
> Bad colums in general must be taken care of at an earlier stage of
> the pipeline than currently implemented (see example ps
> file). This was already discussed by Mark and Roeland.
>
>- SWARP:
> The pipeline currently uses a beta version of Swarp (swarp 2.0b),
> that fails to create usable weight images. Reasonable weight
> images are essential for obtaining a fast run-time with cosmicfits,
> and are crucial when the frames on which cosmic rays are detected
> have strong intensity slopes.
>
>- UPDATES:
> Unannounced pipeline changes that change object definitions, require
> changes to the database, that can be time consuming, given the fact,
> that we have to figure out the changes from the code, and guess
> the needed Database changes. Usually Danny sends out an e-mail
> explaining the required changes (usually after talking with Roeland
> about the changes in the pipeline), but these e-mail come about 2
> days after the changes, causing severe interruptions.
>
> Suggestion: Create a stable branch of the pipeline in the CVS with
> weekly? updates from a development branch, and the changes in these
> updates should be discussed with the DBAs before, so that updates to
> the pipeline cause as few interruptions as possible.
>
>
>
>- TESTS:
>
> - Bias:
>
> Subtracting resulting masterbias from its raw input frames
>
> rawbias file name median stddev average stddev
> seWFI.2003-01-05T20C54C42.283_4.fits -0.199997 18.876 -0.244914 18.8759
> seWFI.2003-01-05T20C55C44.983_4.fits -0.100006 18.9255 -0.161555 18.9254
> seWFI.2003-01-05T20C56C42.354_4.fits 0.100006 18.89 0.00905352 18.8897
> seWFI.2003-01-05T20C57C39.851_4.fits 0.100006 18.9164 -0.00907611 18.916
> seWFI.2003-01-05T20C58C34.232_4.fits 0 18.8818 -0.0418041 18.8818
> seWFI.2003-01-05T20C59C33.157_4.fits 0 18.881 -0.0651421 18.8809
> seWFI.2003-01-05T21C00C32.066_4.fits 0 18.8516 -0.0559038 18.8515
> seWFI.2003-01-05T21C01C33.362_4.fits 0 18.888 -0.0407198 18.888
> seWFI.2003-01-05T21C02C30.338_4.fits 0.100006 18.8894 0.000104276 18.8891
> seWFI.2003-01-05T21C03C29.919_4.fits 0.100006 18.9252 0.0489991 18.9252
>
> (Is there a numerical round-off occurring in the median computation?).
>
> - DomeFlat:
>
> Flatfielding biassubtracted raw domeflatframes using the processed
> domeflat. ( SEM = std. error)
>
> flatfielded raw flatfield filename median stddev average stddev
> dseWFI.2003-01-06T21C59C26.278_4.fits 17778.8 90.3731 17778.1 90.3702
> dseWFI.2003-01-06T22C00C53.969_4.fits 19056.3 94.5017 19055.6 94.4991
> dseWFI.2003-01-06T22C02C15.050_4.fits 19074.4 94.4472 19073.4 94.4418
>
> - TwilightFlats:
>
> Flatfielding biassubtracted raw twilightflatframes using the processed
> twilightflat. ( SEM = std. error)
>
> flatfielded raw flatfield filename median stddev average stddev
> dseWFI.2003-01-04T00C17C43.159_4.fits 17885.3 122.664 17886 122.662
> dseWFI.2003-01-04T00C19C14.085_4.fits 17161.4 134.724 17161.9 134.723
> dseWFI.2003-01-04T00C21C01.056_4.fits 16581.6 151.299 16582.4 151.297
>
> - Astrometry:
> From visual inspection of stars from the USNO catalog overplotted
> on the image, the astrometric solution determined by the pipeline
> seems to be very accurate even out to the edges.
>
> Hard numbers:
> mean position differences in arcsec:
> RA DEC
> -0.0002 0.0001
>
> mean sigma of the position differences in arcsec:
> RA DEC
> 0.4199 0.4021
>
>
>
>
>Cheers,
>
>
>Mark
>
>
>
>
>
>=====================================================
>Dr. Mark J. Neeser
>
>Institute for Astronomy and Astrophysics, _/ _/ _/ _/_/ _/
>Ludwig-Maximilians-Universitaet Muenchen _/ _/ _/_/ _/ _/ _/ _/
> _/ _/ _/ _/ _/ _/ _/_/
>Scheinerstrasse 1, _/ _/ _/_/ _/ _/
>D-81679 Muenchen, Germany
>
>Tel: +49-89-2180-5995
>Fax: +49-89-2180-6003
>
>email: neeser at usm.uni-muenchen.de
>
>
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