HEAO 1 A2 Piccinotti Catalog: 68 Extragalactic X-Ray Sources

NASA HEASARC provides the HEAO 1 A-2 Piccinotti Catalog, a flux-limited sample of 68 non-galactic X-ray sources from a 1977-1979 sky survey. The catalog covers 65.5% of the sky, excluding the galactic plane, and lists 61 identified extragalactic sources and 7 unidentified ones. Data collection occurred during two independent scans in 1977-1978, with sources detected at a minimum statistical significance of 5 sigma.

Use Cases

• Analyze the spatial distribution of extragalactic X-ray sources based on the 8.23 steradian sky coverage.
• Study the completeness and flux limits of X-ray surveys based on the 1.25 and 1.8 R15 ct/s thresholds for the two scans.
• Identify and classify X-ray source types based on the categories of narrow/broad emission line galaxies, BL Lacertae objects, and clusters of galaxies mentioned.
• Validate source detection methods using the 5 sigma statistical significance requirement applied in the catalog creation.

Strengths

• Sources are detected with a high confidence threshold of 5 sigma statistical significance.
• Catalog is flux-limited and covers a defined 65.5% of the sky (8.23 steradians), excluding the galactic plane to minimize contamination.
• Contains 68 specific sources (61 identified, 7 unidentified) from a published, peer-reviewed table.

Limitations

• Column-level documentation is absent; field semantics must be inferred after download.
• Row count is unknown, which may limit suitability assessment.
• Data is from a specific mission in the late 1970s; newer missions may have superseded some findings.

Provenance

Source

National Aeronautics and Space Administration (NASA HEASARC)

Collection Method

Data from the HEAO 1 A-2 experiment's two independent, low-background, high-sensitivity sky surveys.

Time Range

Survey operations from 12 August 1977 to 9 January 1979, with scans from 5 September 1977 to 11 September 1978.

Freshness

Last updated 2026-03-13 19:39:26.570022; freshness should be verified.

Geography

Full sky survey excluding the region between galactic latitudes -20 and +20 degrees and a 6-degree radius around the Large Magellanic Cloud.