Swift Simultaneous UV, Optical, and X-Ray Observed Quasar Catalog

843 optically selected quasars with simultaneous UV/optical and X-ray observations from the Swift Gamma-ray Burst Explorer. The catalog was compiled by NASA by matching Swift pointings with the Sloan Digital Sky Survey DR5 quasar catalog, with 354 objects having full spectral energy distributions. The data was last updated in March 2026.

Use Cases

• Studying the alpha_ox - L_2500A relation using a clean sample of Type 1 radio-quiet quasars.
• Analyzing the contribution of the big blue bump to quasar luminosity based on spectral energy distribution fits.
• Investigating correlations between spectral indices (alpha_UV, alpha_x, alpha_ox) and accretion state (L_bol/L_Edd).
• Comparing quasar properties between sources with high and low XRT exposure times, given the ~85% detection rate for exposures over 10 ks.

Strengths

• Contains 843 objects with simultaneous multi-wavelength observations, reducing variability bias.
• Includes 354 quasars with full spectral energy distributions constructed from UVOT photometry and XRT spectra.
• The X-ray detection rate is ~60% overall and rises to ~85% for sources with at least 10 ks of XRT exposure time.

Limitations

• Column-level documentation is absent; field semantics must be inferred after download.
• Row count for the final curated sample is ambiguous (843 vs. 1034 objects in the raw catalog).
• Data may reflect temporal bias inherent to the 3.5-year Swift observation window and the SDSS DR5 catalog.

Provenance

Source

National Aeronautics and Space Administration (NASA)

Collection Method

Objects were identified by matching Swift pointings (from launch through June 2008) with the Sloan Digital Sky Survey (SDSS) Data Release 5 (DR5) quasar catalog within a 20 arcminute field of view.

Time Range

Observations from Swift's launch through June 2008.

Freshness

Last updated 2026-03-13 19:24:02.590601; freshness should be verified.

Geography

Extragalactic; celestial coordinates.