Skip to the navigation links
Last modified: 24 November 2020

URL: https://cxc.cfa.harvard.edu/csc/news.html

What's new for the Chandra Source Catalog?


November 24, 2020

CSC 2.0.1 Variability Update

Release 2.0.1 of the Chandra Source Catalog updates intra-observation and inter-observation variability properties to resolve two issues detected in release 2.0. These issues resulted in an underestimation of the variability probabilities in release 2.0 for some CSC sources at the Stacked Observation Detection and Master Source levels. When computing the variability properties, CSC 2.0.1 now uses all observations that contribute to a particular stacked observation detection and/or master source, whereas release 2.0 incorrectly used only the observations in the best Bayesian block. In addition, an error that caused incorrect calculations of the inter-observation variability properties when one or more per-observation detections included upper limits for the fluxes, and/or lower or upper limits for the hardness ratios, was fixed. The updated catalog properties have been thoroughly tested and corrected variability probabilities are verified for detections and/or sources for which the values were previously underestimated, and for statistical consistency with CSC 2.0. At the Stacked Observation Detection and Master Source levels, properties affected by this change are: var_inter_hard_prob_{hs,ms,hm}, var_inter_hard_sigma_{hs,ms,hm}, var_inter_prob_{b,h,m,s,u,w}, var_inter_index_{b,h,m,s,u,w}, var_inter_sigma_{b,h,m,s,u,w}, ks_intra_prob_{b,h,m,s,u,w}, kp_intra_prob_{b,h,m,s,u,w}, var_intra_prob_{b,h,m,s,u,w}, var_intra_index_{b,h,m,s,u,w}, var_inter_hard_flag, and var_flag.

Please see the caveats page for any known issues with this release, and for an overview of items that have changed over the course of the validation and verification phase.

October 24, 2019

Version 2.0 of the Chandra Source Catalog (CSC) has been finalized and released to the community. The catalog contains 317,167 unique sources, and 928,280 per-observation detections of ACIS and HRC public imaging observations taken through the end of 2014. There are close to 1700 columns of tabular data with pertinent information about each source across 5 bands (b, h, m, s, u) for ACIS and 1 band (w) for HRC, and 40 data products per source. The total size of the archive is approximately 36 TB.

Please see the caveats page for any known issues with this release, and for an overview of items that have changed over the course of the validation and verification phase.

December 2017

CSCview access to CSC 2.0

Source properties - such as fluxes, variability measurements, and spectral fit results - and data products - event files, images, spectra - from CSC 2.0 are being made available to the community as they are processed. Data access is via CSCview or ADQL, and the current processing-status page provides an overview of the available data.

While all sources have undergone standard quality assurance evaluations, some may be deleted or have their properties revised as a result of further quality-assurance analyses step prior to the official CSC 2.0 release.

November 2017

CSC release 2.0 pre-release (pre1)

The pre-release of the Chandra Source Catalog 2.0 is now available. Please see the caveats for this release before use. It adds source designations (name, position and error, and an estimate of the average flux) to the pd2 detections list.

September 2017

CSC release 2.0 preliminary production release (pd2)

The latest release of the preliminary-detections list of the Chandra Source Catalog 2.0 is now available. Please see the caveats for this release before use. It supercedes the pd1 release from March 2017.

March 2017

CSC release 2.0 preliminary production release (pd1)

The initial release of the preliminary-detections list of the Chandra Source Catalog 2.0 is now available. Please see the caveats for this release before use. It supercedes the pd0 release from August 2015.

August 2015

CSC release 2.0 preliminary data release (pd0)

The first preliminary detections list from release 2.0 of the catalog has been released to the community.

April 2015

Processing starts

Production of version 2 of the Chandra Source Catalog began in April 2015.