NORAS: X-ray Galaxy Cluster Catalog from ROSAT All-Sky Survey

A catalog of 495 X-ray sources identified as extended emission in the first processing of the ROSAT All-Sky Survey (RASS I), covering the northern celestial region. The National Aeronautics and Space Administration (NASA) provides this data, which includes 378 confirmed galaxy clusters and supplementary findings from a later RASS II analysis. The catalog's parameters were refined using a growth curve analysis (GCA) technique for more precise X-ray flux and source extent measurements.

Use Cases

• Estimate galaxy cluster number counts for cosmological studies based on X-ray flux and source extent.
• Identify and classify extended X-ray sources based on combined optical and X-ray data mentioned in the description.
• Assess survey completeness for statistical analyses based on the described comparison with the REFLEX survey.
• Study the X-ray properties of known clusters, such as the 85 additional Abell clusters found.

Strengths

• Contains 495 X-ray sources with 378 (76%) confirmed as galaxy clusters.
• Uses a robust growth curve analysis (GCA) method for precise X-ray flux and source extent parameters.
• Includes supplementary findings from RASS II, adding 85 Abell clusters and 56 probable new candidates in a study region.

Limitations

• The sample completeness is estimated at about 50% at a specific flux limit, introducing uncertainty for cosmological statistics.
• Column-level documentation is absent; field semantics must be inferred after download.
• Row count is unknown, which may limit suitability assessment.

Provenance

Source

National Aeronautics and Space Administration

Collection Method

X-ray source characterization via growth curve analysis (GCA) of ROSAT All-Sky Survey (RASS) data, combined with optical follow-up identification.

Time Range

Based on observations from the ROSAT All-Sky Survey (RASS I and RASS II).

Freshness

Last updated 2026-03-13 17:45:47.963804; freshness should be verified.

Geography

Northern celestial region with declination >=0 degrees and Galactic latitude |b| >= 20 degrees.