contains 526,280,881 sources, and is based on a
re-reduction of the Precision Measuring Machine (PMM) scans
from POSS-I O and E plates (>=-18°) and SRC-J and
ESO-R plates (<=-20°).
USNO-A2.0 was created by Dave Monet (Flagstaff Station, U.S. Naval Observatory.
The major difference between USNO-A2.0 and its previous version
USNO-A1.0 is that A1.0 used the
Guide Star Catalog as its reference frame whereas
A2.0 uses the ICRF as realized by the
USNO ACT catalog (Urban et al. 1997).
The VizieR search engine uses an
on-line compressed version
(3.6Gbytes) which was generated at CDS.
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: 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: UCAC5 document
(original column names in green) (1692919135 rows)
(original column names in green) (1811709771 rows)
Note: The data from the Catalogue of Nearby Stars are directly accessible from the Woolley column
Note: See also the ARICNS (Astronomische Rechen-Institut database for Nearby Stars); some errors can be found in notes.tex
Note: The column expnum provides an access to details on the exposures, and a link to the Preview and Retrieval System via the CADC