CSCASSOC - Chandra Source Catalog Master Source-Stacked Source Associations, v2.2

Overview

The Chandra Source Catalog (CSC ) is the definitive catalog of X-ray sources detected by the Chandra X-ray Observatory. By combining Chandra's sub-arcsecond on-axis spatial resolution and low instrumental background with consistent data processing, the CSC delivers a wide variety of uniformly calibrated properties and science ready data products for detected sources over four decades of flux. The catalog, the Stacked Observation Detections Table (CSCSTACK) includes 527,230 detections (and 960,929 detections and photometric upper limits) based on 11,317 X-ray observations stacks.

This table maps the master sources table CSC records to their associated stacked observation detections CSCSTACK, and also identifies the type of linkage (unique, ambiguous, or non-detection) that associates the two.

Catalog Bibcode

2024ApJS..274...22E

References

Chandra Source Catalog Release 2 (CSC Release 2 Series).
    Evans I.N., Evans J.D., Martinez-Galarza J.R., Miller J.B., Primini F.A.,
    Azadi M., Burke D.J,. Civano F.M,. D'Abrusco R., Fabbiano G.,
    Graessle D.E., Grier J.D., Houck J.C., Lauer J., McCollough M.L.,
    Nowak M.A., Plummer D.A., Rots A.H., Siemiginowska A., Tibbetts M.S.
   <Astrophys. J. Suppl. Ser.,, 274, 22 (2024)>
   =2024ApJS..274...22E
   =2024yCat.9070....0E

Provenance

This database table was last updated by the HEASARC in November 2026 and is based on a download of the online version of the "Master Source/Stack Source Associations" table, version 2.2, at the CXC using the CLI. Refer to https://cxc.harvard.edu/csc/cli/ for details.

Links to Related CSC Tables

Chandra Source Catalog, v2.2 (CSC): The master sources table includes measured properties for 432,713 unique compact and extended X-ray sources in the sky. By combining Chandra's sub-arcsecond on-axis spatial resolution and low instrumental background with consistent data processing, the CSC delivers a wide variety of uniformly calibrated properties and science ready data products for detected sources over four decades of flux.

Chandra Source Catalog Stacked Observation Detections, v2.2 (CSCSTACK) includes 527,230 detections (960,929 total entries consisting of detections plus photometric upper limits) based on 11,317 stacks of X-ray observations. Exploiting the unique resolution and very low background of Chandra data, the limiting sensitivity of the catalog is enhanced significantly by stacking (co-adding) multiple observations of the same field prior to source detection.

Chandra Source Catalog Stacked Source-Observation Source Associations, v2.2 (CSCSTOBAS) maps the stacked observation detections table (CSCSTACK) records to their associated per-observation data in (CSCSTACKOB).

Chandra Source Catalog Stacked Source Per-Observation Detections, v2.2(CSCSTACKOB) includes 1,433,096 detections (and 2,536,232 detections and upper limits) from 17,879 observations. Extracted properties are provided for these individual observation detections identified in Chandra ACIS and HRC-I imaging observations released publicly through the end of 2024.

For more details about the catalog organization, please refer to the CXC page.

Parameters

Name
The Chandra Source Catalog name in the IAU position-based nomenclature, viz., '2CXO Jhhmmss.s{+,-}ddmmss', where the 'CXO' stands for Chandra X-ray Observatory and the '2' stands for version 2 of this catalog. A name ending with "X" designates a highly extended "convex hull" source. (CXC: master_stack_assoc.name)

Detect_Stack_ID
The detection stack identifier (designation of observation stack used for source detection) in the format '{acis|hrc}fJhhmmsss{p|m}ddmmss_nnn' where Jhhmmss{p|m}ddmmss is the J2000 coordinates in sexagesimal units with hh, mm, ss providing hours, minutes and seconds for the RA component and p/m gives the '+/-' along with the dd, mm, ss for the decimal degrees for the Declination component. The nnn designates the catalog version id and may be '001' or '002' for the stacks. Stacks that end in '_002' are ones that have extra observations compared to CSC 2.0, whereas a stack that ends in '_001' either was in CSC 2.0 and has now new data, or was not in CSC 2.0. (CXC: master_stack_assoc.detect_stack_id)

Region_ID
The detection region identifier (component number). (CXC: master_stack_assoc.region_id)

Match_Type
The type of match between the master source and stacked observation detection. The flag [UAN] indicates the following:

  	U      =     Unique Match
  	A      =     Ambiguous Match
  	N      =     Non-Detection

(CXC: master_stack_assoc.match_type)

Contact Person

Questions regarding the CSCASSOC database table can be addressed to the HEASARC Help Desk.

Page Author: Browse Software Development Team
Last Modified: Thursday, 05-Nov-2026 17:18:43 EST