- ID:
- ivo://fs.usno/cat/nomad
- Title:
- NOMAD Catalogue
- Short Name:
- NOMAD
- Date:
- 11 Apr 2007 08:52:38
- Publisher:
- 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.
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- ID:
- ivo://fs.usno/cat/usnob
- Title:
- USNO-B1 Catalogue
- Short Name:
- USNO-B1
- Date:
- 03 Feb 2020 22:21:11
- Publisher:
- 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.
