[vsnet-chat 1921] GSC v1.2 on-line!

[bas@lowell.Lowell.Edu (Brian Skiff)]

     Today's Strasbourg VizieR new-catalogue listing contains a rather
unexpected surprise:  the GSC verision 1.2, avialable both for look-up and
as a complete catalogue.  Some details can be found starting at:

http://vizier.u-strasbg.fr/viz-bin/Cat?I/254

In brief, this is a revision of the "traditional" GSC based on an 
astrometric re-reduction using the PPM star catalogue as the reference net.
Besides putting the GSC more strictly on the FK5 system---and very close to
the Hipparcos-based ICRS---additional work was done on correcting the
systematic errors in the GSC that appear as a function of sky zone, 
star magnitude, and location of stars on a particular plate.  The bottom
line here is that compared against external high-accuracy data such as the
Carlsberg meridian circle, the GSC v1.2 has positions good to +/- 0".3 to
0".4 for the whole sky for epoch about 1980.  This is quite a bit better
than USNO-A2.0 (current external errors about 0".5).  Folks using the GSC
for astrometry should certainly adopt v1.2 in place of the commonly used
version 1.1.

\Brian

VSNET Home Page

Return to Daisaku Nogami

---

vsnet-adm@kusastro.kyoto-u.ac.jp