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The Fifth U.S. Naval Observatory CCD Astrograph Catalog

Metadata Updated: April 10, 2026

The US Naval Observatory (USNO) has a long history of providing accurate astrometric data for millions of stars from their own observations plus other data. The USNO CCD Astrograph Catalog (UCAC) project utiized the "redlens" 20 cm aperture astrograph in an all-sky observing program between 1997 and 2004 (CTIO in the south, NOFS in the north) with a limiting magnitude of about R = 16.5. The previous release, UCAC4, became available in 2012. The 1st Gaia data release provides proper motions for only about 2 million stars (TGAS subset of the Tycho-2 stars) in the mainly 6 to 11.5 magnitude range. Gaia DR2 which will contain proper motions of about a billion stars is scheduled for release in April 2018. In the meantime the astronomical community would benefit from proper motions of millions of stars fainter than the Tycho-2 limit, if a substantial improvement in precision and accuraccy could be made beyond what was available in the pre-Gaia era. Re-reduction of UCAC + combine with Gaia DR1 provides proper motions for over 107 million stars on the 1 to 5 mas/yr level, strongly depending on magnitude. UCAC observations (mean epoch 2001) provide positions with 10 to 70 mas precision, and about 14 years of epoch difference to Gaia DR1.

Access & Use Information

Public: This dataset is intended for public access and use. License: See this page for license information.

Downloads & Resources

Dates

Metadata Created Date April 11, 2025
Metadata Updated Date April 10, 2026

Metadata Source

Harvested from NASA Data.json

Additional Metadata

Resource Type Dataset
Metadata Created Date April 11, 2025
Metadata Updated Date April 10, 2026
Publisher NASA/IPAC Infrared Science Archive
Maintainer
Identifier ivo://irsa.ipac/usno/catalog/ucac5
Data Last Modified 2026-04-06
Category Astrophysics
Public Access Level public
Bureau Code 026:00
Metadata Context https://project-open-data.cio.gov/v1.1/schema/catalog.jsonld
Schema Version https://project-open-data.cio.gov/v1.1/schema
Catalog Describedby https://project-open-data.cio.gov/v1.1/schema/catalog.json
Harvest Object Id 9f159c50-32b7-4017-810e-fc5ab4adb360
Harvest Source Id 58f92550-7a01-4f00-b1b2-8dc953bd598f
Harvest Source Title NASA Data.json
Homepage URL ivo://irsa.ipac/usno/catalog/ucac5
License https://www.usa.gov/government-works
Program Code 026:000
Source Datajson Identifier True
Source Hash e711b99fda5397cd1e47ecb878c961003b5d218609a27dfa793a058145646278
Source Schema Version 1.1

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