Status and Version History

Release 2.1.1 of the Chandra Source Catalog resolves four issues detected in release 2.1.

1. Source names in the Master Sources Table for 400 sources that had been previously identified and published in CSC 2.0 were incorrect in CSC 2.1. These source names are corrected in CSC 2.1.1. Most of the affected sources were located in the vicinity of SNR E0102-72.3. For a list of corrected source names see here.
2. Some properties (primarily aperture photometry properties and properties derived from them, such as hardness ratios and temporal variability) for approximately 7,000 sources in the Master Sources Table and detections in the Stacked Observation Detections Table may be incorrectly set to NULL in some energy bands in CSC 2.1. This occurs for master sources and stacked observation detections for which one or more ACIS observations has energy bands truncated by onboard PHA filters. These source properties are correctly populated in CSC 2.1.1. Most of the affected sources were located in the vicinity of Sgr A*.
3. For highly extended (convex hull) detections listed in the Per-Observation Detections Table, the relative astrometry offsets deltax and deltay were incorrectly reported in pixels rather than arcseconds. These properties are correctly reported in arcseconds in CSC 2.1.1.
4. The individual observation manual astrometry flag listed in the Per-Observation Detections Table may have been incorrectly set to FALSE if the detection was originally identified in CSC 2.0. These flag is correctly set in CSC 2.1.1.

The release of the Chandra Source Catalog (CSC release 2.1) includes data for 407,806 unique sources and 1,304,376 individual observation detections of ACIS and HRC public imaging observations through the end of 2021. There are approximately 1700 columns of tabular data with pertinent information about each source across 5 bands (broad, hard, medium, soft, and ultra-soft) for ACIS and 1 band (wide) for HRC (see the energy-bands page for the definition of these bands), and 40 data products per source. The total size of the archive is close to 44 TB.