Note: This Hipparcos INPUT catalog was used by the Hipparcos mission; the result of the Hipparcos mission is the catalog I/239/hip_main
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: Note that the J2000 coordinates are not part of the original catalogue, they were computed from dRAs and dDEs, or from the (rho,theta); their accuracy can be low.
Note: the J2000 coordinates are not part of the original catalogue; their accuracy can be low, see the CooFlag column
The Naval Observatory Merged Astrometric Dataset (NOMAD) contains
astrometric and photometric data for over 1 billion stars derived from
the Hipparcos (I/239), Tycho-2 (I/259), UCAC2 (I/289), and USNO-B1.0
(I/284) catalogs for astrometry and optical photometry, supplemented
by 2MASS (II/246) near-infrared photometry.
An efficient remote query program findnomad1 is
available in the cdsclient
package, for Unix/Linux platforms
Note: The limiting magnitude is about 15.2 in the GSC photometric system.
Note: see the UCAC4 document, and the
the fix for high proper motion stars.
The UCAC home page is available at
Please acknowledge the usage
of the UCAC4
Note: Many errors detected in the positions given in the catalogue, especially in the sign of the declination in the zones -1°<δ<+1°