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: 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
Note: 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 http://www.usno.navy.mil/USNO/astrometry/optical-IR-prod/ucac. Please acknowledge the usage of the UCAC4
Note:
Note: Many errors detected in the positions given in the catalogue, especially in the sign of the declination in the zones -1°<δ<+1°