USNO-B: All-Sky Catalog of 1 Billion Celestial Objects

An all-sky catalog presenting positions, proper motions, magnitudes, and star/galaxy estimators for 1,042,618,261 objects. The data were derived from 3,643,201,733 observations across 7,435 Schmidt plates taken over approximately 50 years. The catalog was constructed by the United States Naval Observatory and is mirrored by the Mikulski Archive for Space Telescopes (MAST).

Use Cases

• Calibrating astrometric positions for other observations based on the catalog's reported 0.2 arcsecond accuracy.
• Training star/galaxy classification models based on the 85% accuracy estimator provided.
• Studying stellar proper motions over time using the derived motion data.
• Performing photometric analysis in multiple optical passbands based on the reported 0.3 magnitude accuracy.

Strengths

• Extremely large scale with over 1 billion cataloged objects.
• Derived from a massive base of over 3.6 billion separate observations.
• Claims all-sky coverage and completeness down to visual magnitude V=21.
• Provides data in up to five optical passbands with 0.3 magnitude photometric accuracy.

Limitations

• Column-level documentation is absent; field semantics must be inferred after download.
• Row count is unknown, which may limit suitability assessment.
• Data freshness should be verified; the catalog is based on plates taken over the last 50 years.

Provenance

Source

United States Naval Observatory (USNO), mirrored by the Mikulski Archive for Space Telescopes (MAST).

Collection Method

Derived from scans of 7,435 Schmidt plates taken for various sky surveys.

Time Range

Observations collected over approximately 50 years prior to catalog publication (circa 2003).

Freshness

Last updated 2026-03-13 16:52:54.584925; freshness should be verified.

Geography

All-sky (global celestial) coverage.