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 construction of the
is still in progress: this
version has no proper motions, and the magnitude limits are 18.5 in F (red)
and 19.5 in J (blue). The data are copyrighted, check
the data use Policy.
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: This version of the
has no proper motions, but the limits on brightness which existed on
GSC2.2 (F<18.5, Bj<19.5) were removed.
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: Zone -40/+50deg
Note: The ``short'' version of the catalogue can be retrieved by a selecting *+* in the SEQflags column
Note: Details of surveyed literature