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: Detailed introduction can be found in intro.tex (see also http://aries.usno.navy.mil/ad/ac.html) Direct links to Hipparcos and Tycho observations are provided from the relevant columns.
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
(original column names in green) (1692919135 rows)
(original column names in green) (1811709771 rows)
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