[vsnet-survey 69] (fwd) GSC-2.2 at VizieR

[Taichi Kato <tkato@kusastro.kyoto-u.ac.jp>]

Date: Tue, 11 Dec 2001 13:56:51 -0700 (MST)
From: Brian Skiff <bas@lowell.edu>
Subject: [vsnet-chat 4937] GSC-2.2 at VizieR

     The new GSC 2.2, an all-sky catalogue similar to USNO-A2.0, has
become available today via the Strasbourg VizieR utility.  The complete
catalogue is not available, but can be queried in VizieR by object name
or search center.  Using the clunky STScI interface, I have used this
catalogue a lot recently, and find that it provides good astrometry in
many cases where other catalogues fail.  The photometry varies considerably
in quality, even where there is nominally some calibration available.
reas I have examined vary from essentially dead-on in the relevant
passbands to plain-wrong (several magnitudes off).  Since the positions
are Tycho-2 based, and the plate-scans have been done at higher resolution,
the astrometry should have significantly smaller internal and external
errors than USNO-A2.0.  An article in the recent ESO "Messenger" about
calibration of their EIS wide-field survey shows notable improvement in 
the astrometry compared to A2.0.
     For those who are counting, the catalogue has "only" 455 million
entries with a nominal cutoff for mag. 19.5 on J (blue-light) plates.
Details can be found at:

http://vizier.u-strasbg.fr/viz-bin/Cat?I/271

\Brian

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