Note: The Guide Star Catalog has been constructed to support the operational need of the Hubble Space Telescope. It contains over 25 million positions for about 19 million objects, of which more than 15 million are classified as stars. The version 1.2 is a new astrometric reduction which results in absolute position errors about 0.3-0.4 arcsec. (see GSC pages at URL http://www-gsss.stsci.edu/gsc/gsc.html)
Note: The GSC-ACT (or GSC1.3) is a recalibration of the GSC1.1, the catalogue constructed to support the operational need of the Hubble Space Telescope, with the ACT, the combination of the Astrographic Catalogue and the Tycho catalogue derived from the Hipparcos mission; see http://www.projectpluto.com/gsc_act.htm for more details about this recalibration.
Note: The current version includes only the North (POSS-I plates)
Note: Zone -30/+50deg
Note:
Note: Zone -40/+50deg
(original column names in green) (1692919135 rows)
(original column names in green) (1811709771 rows)
Note: SDSS is also available from http://www.sdss.org/
Note: SDSS is also available from http://www.sdss3.org/dr9/