UCAC4: All-Sky Star Catalog with Proper Motions and Photometry

113 million stars are cataloged in UCAC4, covering the sky from the brightest stars to about magnitude R=16. The U.S. Naval Observatory compiled this catalog using CCD observations supplemented by data from about 140 other catalogs for proper motions, 2MASS for photometry, and APASS for 5-band photometry. It was last updated in March 2026.

Use Cases

• Calculate stellar proper motions based on the multi-epoch catalog cross-referencing mentioned in the description.
• Analyze photometric properties of stars based on the integrated B,V,g,r,i and 2MASS band data.
• Identify and flag bright star sources based on the Hipparcos and Tycho-2 supplement data indicated in the catalog flags.
• Assess positional accuracy for celestial mapping based on the 15-20 mas error estimates for stars in the 10-14 magnitude range.

Strengths

• Covers approximately 113 million stars, providing a substantial sample for all-sky analysis.
• Integrates data from about 140 other star catalogs to derive proper motions, enhancing temporal coverage.
• Supplements core data with 2MASS photometry for about 110 million stars and APASS 5-band photometry for over 50 million stars.
• Provides positional error estimates of about 15 to 20 mas for stars in the 10 to 14 magnitude range.

Limitations

• Column-level documentation is absent; field semantics must be inferred after download.
• Row count is unknown, which may limit suitability assessment for specific computational tasks.

Provenance

Source

National Aeronautics and Space Administration

Collection Method

Compiled from U.S. Naval Observatory CCD astrograph observations, cross-referenced with about 140 other star catalogs, and supplemented with 2MASS and APASS survey data.

Time Range

null

Freshness

Last updated 2026-03-13 17:49:30.532802; freshness should be verified.

Geography

All-sky (global celestial coverage)