FIRST: Faint Images of the Radio Sky at 20cm Survey Catalog

The Faint Images of the Radio Sky at Twenty cm (FIRST) Survey catalog contains radio source detections from observations between 1993 and 2011. It covers approximately 10,575 square degrees of the north and south Galactic caps, with a typical detection limit of 1 milliJansky. This 14Dec17 version is provided by the National Aeronautics and Space Administration and includes refinements for improved flux accuracy and source reliability.

Use Cases

• Cross-matching radio sources with optical counterparts based on the SDSS overlap mentioned in the description
• Analyzing radio source flux density distributions based on the 1 mJy detection limit
• Studying source reliability and sidelobe probability using the P(S) parameter
• Investigating survey coverage gaps and calibration differences between VLA and EVLA observations

Strengths

• Covers a large area of approximately 10,575 square degrees of sky
• Includes observations spanning 18 years from 1993 to 2011
• Flux densities are described as more accurate with reduced biases compared to previous versions
• Contains approximately 4,500 sources below the 1 mJy threshold for deeper analysis

Limitations

• Column-level documentation is absent; field semantics must be inferred after download
• Row count is unknown, which may limit suitability assessment
• Small gaps in sky coverage exist at boundaries between EVLA and VLA regions

Provenance

Source

National Aeronautics and Space Administration

Collection Method

Observations from the Very Large Array (VLA) and Expanded Very Large Array (EVLA) radio telescopes.

Time Range

1993 through 2011

Freshness

Last updated 2026-03 13 19:11:17.895302; freshness should be verified

Geography

North and south Galactic caps, coinciding approximately with the Sloan Digital Sky Survey area.