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)
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: UCAC5 document
(original column names in green) (1692919135 rows)
Note: SDSS is also available from http://www.sdss.org/
Note: Errors found in the Final IUE Merged log are reported in the file errata.htx
Note: (see also the postcard server)
Note: The ``short'' version of the catalogue can be retrieved by a selecting *+* in the SEQflags column
Note: The column expnum provides an access to details on the exposures, and a link to the Preview and Retrieval System via the CADC