Chandra Source Catalog Stacked Observation Detections, v2.1.1

The stacked-observation level allows composite properties to be reported from the co-added observations for detections that would otherwise not be visible or have poor S/N in individual observations, while for higher S/N detections the per-observation properties facilitate analysis of variable sources. CSCSTACK is related to the <a href="/W3Browse/chandra/csc.html">Chandra Source Catalog (CSC)</a> catalog, which is the definitive catalog of X-ray sources detected by the Chandra X-ray Observatory.

The CSC contains 407,806 unique compact and extended X-ray sources. 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. Each identified distinct X-ray source on the sky is represented in the catalog by one or more "stack detection" entries -- one for each stack in which the source has been detected -- and a single "master source" entry.

The individual stack entries record all of the properties about a detection extracted from a single stack, as well as associated file-based data products, which are stack-specific. If a source is detected in one or more stacked-observations, photometric upper limits that are useful for temporal variability analyses are calculated for any overlapping stacked- and individual-observations in which the source is not detected.

This database table was ingested by the HEASARC in July 2026 and is based on a download of the online version of the "Stacked Observation Detections" Table v. 2.1.1, at the CXC using the CLI. Refer to <a href="cxc.harvard.edu/csc/cli/">https://cxc.harvard.edu/csc/cli/</a> for details. This is a service provided by NASA HEASARC .