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Chandra Deep Field South 4-Megasecond Catalog

Metadata Updated: April 10, 2026

This table contains the main Chandra source catalog for the 4 megasecond (Ms) Chandra Deep Field-South (CDF-S), which is the deepest Chandra survey to date and covers an area of 464.5 arcmin<sup>2</sup>. It contains 740 X-ray sources that are detected with wavdetect at a false-positive probability threshold of 10<sup>-5</sup> in at least one of three X-ray bands (0.5-8 keV, full band; 0.5-2 keV, soft band; and 2-8 keV, hard band) and also satisfy a binomial-probability source-selection criterion of P < 0.004 (i.e., the probability of sources not being real is less than 0.004); this approach is designed to maximize the number of reliable sources detected. A total of 300 main-catalog sources are new compared to the previous 2 Ms CDF-S main-catalog (the HEASARC CHANDFS2MS table) sources. The authors determined X-ray source positions using centroid and matched-filter techniques and obtained a median positional uncertainty of ~0.42 arcseconds. In their paper, they also provided a supplementary catalog (not included in this HEASARC table), which consists of 36 sources that are detected with wavdetect at a false-positive probability threshold of 10<sup>-5</sup>, satisfy the condition of 0.004 < P < 0.1, and have an optical counterpart with R < 24. Multiwavelength identifications, basic optical/infrared/radio photometry, and spectroscopic/photometric redshifts are provided for the X-ray sources in the main and supplementary catalogs. Seven hundred sixteen (~97%) of the 740 main-catalog sources have multiwavelength counterparts, with 673 (~94% of 716) having either spectroscopic or photometric redshifts. The 740 main-catalog sources span broad ranges of full-band flux and 0.5-8 keV luminosity; the 300 new main-catalog sources span similar ranges although they tend to be systematically lower. Basic analyses of the X-ray and multiwavelength properties of the sources indicate that >75% of the main-catalog sources are active galactic nuclei (AGNs); of the 300 new main-catalog sources, about 35% are likely normal and starburst galaxies, reflecting the rise of normal and starburst galaxies at the very faint flux levels uniquely accessible to the 4 Ms CDF-S. Near the center of the 4 Ms CDF-S (i.e., within an off-axis angle of 3'), the observed AGN and galaxy source densities have reached 9800 (+1300,-1100) deg<sup>-2</sup> and 6900 (+1100,-900) deg<sup>-2</sup>, respectively. Simulations show that the main catalog is highly reliable and is reasonably complete. The mean backgrounds (corrected for vignetting and exposure-time variations) are 0.063 and 0.178 counts Ms<sup>-1</sup> pixel<sup>-1</sup> (for a pixel size of 0.492 arcseconds) for the soft and hard bands, respectively; the majority of the pixels have zero background counts. The 4 Ms CDF-S reaches on-axis flux limits of ~3.2 x 10<sup>-17</sup>, 9.1 x 10<sup>-18</sup>, and 5.5 x 10<sup>-17</sup> erg cm<sup>-2</sup> s<sup>-1</sup> for the full, soft, and hard bands, respectively. An increase in the CDF-S exposure time by a factor of ~2-2.5 would provide further significant gains and probe key unexplored discovery space. This HEASARC table comprises Table 3 from the reference paper, the Main Chandra Source Catalog of 740 X-ray sources. The 36 optically bright Chandra sources that were listed in Table 6 of the reference paper are thus not included herein. This table was created by the HEASARC in July 2011 based on an electronic version of Table 3 from the reference paper which was obtained from the ApJS web site. This is a service provided by NASA HEASARC .

Access & Use Information

Public: This dataset is intended for public access and use. License: See this page for license information.

Downloads & Resources

Dates

Metadata Created Date April 11, 2025
Metadata Updated Date April 10, 2026

Metadata Source

Harvested from NASA Data.json

Additional Metadata

Resource Type Dataset
Metadata Created Date April 11, 2025
Metadata Updated Date April 10, 2026
Publisher High Energy Astrophysics Science Archive Research Center
Maintainer
Identifier ivo://nasa.heasarc/chandfs4ms
Data Last Modified 2026-04-06
Category Astrophysics
Public Access Level public
Bureau Code 026:00
Metadata Context https://project-open-data.cio.gov/v1.1/schema/catalog.jsonld
Schema Version https://project-open-data.cio.gov/v1.1/schema
Catalog Describedby https://project-open-data.cio.gov/v1.1/schema/catalog.json
Harvest Object Id b551db42-4b4b-4ea5-ae88-41b1c5531ae3
Harvest Source Id 58f92550-7a01-4f00-b1b2-8dc953bd598f
Harvest Source Title NASA Data.json
Homepage URL ivo://nasa.heasarc/chandfs4ms
License https://www.usa.gov/government-works
Program Code 026:000
Source Datajson Identifier True
Source Hash b0adb6e63c8c04f3b06aad89ab905e7f6ef3e319bee6d62adad28d4277037ee4
Source Schema Version 1.1

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