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Release of the Second XMM-Newton Serendipitous Source Catalogue: 2XMM

Release of the Second XMM-Newton Serendipitous Source Catalogue: 2XMM

7 September 2007

The 2XMM catalogue of X-ray sources, the largest of its kind ever, has now been released. The catalogue has been created by the XMM-Newton Survey Science Centre (SSC), a consortium of institutions across Europe, on behalf of ESA. It contains source detections drawn from 3491 observations made with XMM-Newton's European Photon Imaging Cameras (EPIC) between February 2000 and March 2007.

The catalogue production process used by the SSC has been designed to exploit fully the X-ray imaging and spectroscopic capabilities of the XMM-Newton EPIC cameras and to ensure the integrity and quality of the resultant catalogue through rigorous screening of the data.

Comparison of X-ray surveys

The pointed observations with XMM-Newton detect significant numbers of previously unknown serendipitous X-ray sources in addition to the proposed target. Combining the data from many observations yields a serendipitous source catalogue which, by virtue of the large field of view of XMM-Newton and its high sensitivity, represents a significant resource.

The 2XMM catalogue contains 246 897 X-ray source detections which relate to 191 870 unique X-ray sources, making it the largest collection of X-ray objects ever compiled. The total area covered on the sky by the combined observation fields is ~360 square degrees.

The catalogue complements deeper Chandra and XMM-Newton small area studies, probing a large sky area at the flux limit where the bulk of the objects that contribute to the X-ray background lie. It provides a unique dataset for generating large, well-defined samples of various types of high-energy astrophysical objects, including active galaxies, clusters of galaxies, interacting compact binaries and active stellar coronae, since these objects are most efficiently selected at X-ray energies.

The large sky area covered by the catalogue makes 2XMM a rich resource for exploring the overall properties of the X-ray source populations and its large size makes it an especially powerful tool for the discovery of rare and unexpected objects.

The catalogue itself is complemented, for the first time, by X-ray spectra and light-curves of the brighter sources. These additional data form a very valuable scientific resource in their own right, providing detailed diagnostics of astrophysical processes taking place in these brighter objects.

2XMM Catalogue

Number of EPIC observations


Total sky area covered

~360 square degrees

Number of unique sources

191 870

Median flux, full band (0-12 keV)

~2.5 × 10-14 erg/cm²/s

Median flux, soft band (0-2 keV)

~5.8 × 10-15 erg/cm²/s

Median flux, hard band (2-12 keV)

~1.4 × 10-14 erg/cm²/s

Positional accuracy of sources

< ~5 arcseconds

The XMM-Newton Survey Science Centre, led by Prof Mike Watson at the University of Leicester, is a consortium of the following institutions:

University of Leicester, UK
Mullard Space Science Laboratory, University College London, UK
Institute of Astronomy, Cambridge, UK
Max-Planck Institut für extraterrestrische Physik, Garching, Germany
Astrophysikalisches Institut, Potsdam, Germany
Service d'Astrophysique, CEA/DSM/Dapnia, Saclay, France
Centre d'Etude Spatiale des Rayonnements, Toulouse, France
Observatoire Astronomique de Strasbourg, France
Instituto de Fisica de Cantabria, Santander, Spain
Osservatorio Astronomico di Brera, Milan, Italy


Mike Watson, Dept of Physics & Astronomy, University of Leicester, UK

Norbert Schartel, ESA XMM-Newton Project Scientist
European Space Astronomy Centre, Villafranca, Madrid, Spain

Last Update: 1 September 2019
8-Mar-2021 00:50 UT

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