United States Naval Observatory, Flagstaff Station
Description:
The U.S. Naval Observatory (USNO) announces the release of the first version of the Naval Observatory Merged Astrometric Dataset (NOMAD). The 100 GB dataset contains astrometric and photometric data for over 1 billion stars derived from the Hipparcos, Tycho-2, UCAC2, and USNO-B catalogs for astrometry and optical photometry, supplemented by 2MASS near-infrared photometry. For each unique star the "best" astrometric and photometric data are chosen from the source catalogs and merged into a single dataset. A sequence of priorities is followed and NOMAD contains flags to identify the source catalogs and gives cross-reference identifications. This first release of NOMAD is not a compiled catalog; that is, if a star is identified in more than 1 of the above mentioned catalogs, only 1 catalog entry is chosen. Thus the local and global systematic errors of the various source catalogs will be present in this version of NOMAD. All source catalogs astrometric data are on the International Celestial Reference System within the limitations of the source catalogs. For more information and data retrieval see our homepage www.nofs.navy.mil/nomad.
United States Naval Observatory, Flagstaff Station
Short Name:
USNOFS
Date:
11 Apr 2007 08:52:38
Publisher:
US Naval Observatory
Description:
The USNO Flagstaff Station Image and Catalogue archive
provides access to digitized images of the major Schmidt photographic surveys of the sky (POSS-I, POSS-II, SERC-J, SERC-R, SERC-EJ, SERC-ER, AAO-R etc.) and to astrometric catalogues derived from these data, including USNO-A2, USNO-B1 and NOMAD. The site provides catalogue data, finding charts, image data and a merge of the three.
United States Naval Observatory, Flagstaff Station Naming Authority
Short Name:
USNOFS auth
Date:
11 Apr 2007 08:52:38
Publisher:
US Naval Observatory
Description:
The USNO Flagstaff Station Image and Catalogue archive
provides access to digitized images of the major Schmidt photographic surveys of the sky (POSS-I, POSS-II, SERC-J, SERC-R, SERC-EJ, SERC-ER, AAO-R etc.) and to astrometric catalogues derived from these data, including USNO-A2, USNO-B1 and NOMAD. The site provides catalogue data, finding charts, image data and a merge of the three.
United States Naval Observatory, Flagstaff Station
Description:
USNO-B is an all-sky catalog that presents positions, proper motions, magnitudes in various optical passbands, and star/galaxy estimators for 1,042,618,261 objects derived from 3,643,201,733 separate observations. The data were obtained from scans of 7435 Schmidt plates taken for the various sky surveys during the last 50 years. USNO-B1.0 is believed to provide all-sky coverage, completeness down to V=21, 0.2" astrometric accuracy at J2000, 0.3 mag photometric accuracy in up to five colors, and 85% accuracy for distinguishing stars from nonstellar objects. A brief discussion of various issues is given here, but the actual data are available from the US Naval Observatory Web site and others.
