XMM-Newton-NEWS  #246,    18-Aug-2021

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  • New versions of the XMM-Newton Serendipitous Source Catalogues:
    4XMM-DR11 and 4XMM-DR11s

New versions of the XMM-Newton Serendipitous Source Catalogues:
4XMM-DR11 and 4XMM-DR11s

A new version of the XMM-Newton EPIC Serendipitous Source Catalogue, 4XMM-DR11, is being released by the XMM-Newton Survey Science Centre (XMM-SSC) in collaboration with the SOC. This version includes an extra year of data with respect to 4XMM-DR10. 4XMM-DR11 includes 895415 X-ray detections which relate to 602543 unique X-ray sources from 12210 observations that were public by the 31st December 2020. 4XMM-DR11 covers a total sky area, with at least 1 ks exposure, of 1239 square degrees if overlaps are taken into account, where some regions of the sky have been pointed as many as 80 times. Around 13% of all the detections are classified as extended, and spectra and time series have been extracted for 36% of the detections. The median positional uncertainty of the catalogue detections is 1.57 arcseconds (with a standard deviation of 1.43). Median fluxes in the catalogue are ~5.2E-15 and ~1.2E-14 erg/cm2/s in the soft (0.2-2 keV) and hard (2-12 keV) X-ray band, respectively.

With 4XMM-DR11, we release 4XMM-DR11s, the catalogue version created from overlapping observations. Stacking observations provides longer effective exposure times, resulting in better source parameters and higher sensitivity. 4XMM-DR11s is built from 1475 groups with 8292 observations. Most of the stacks are composed of 2 observations and the largest has 357. The catalogue contains 358809 sources, of which 275440 have several contributing observations. It reaches a median flux of ~3.3E-15 and ~1.1E-14 erg/cm2/s in the soft (0.2-2 keV) and hard (2-12 keV) X-ray band, respectively. 8587 good quality sources are variable on the long term.

The detection catalogue is described in the paper Webb et al. (2020) and the stacked catalogue is further described in Traulsen et al. (2020). Details of the catalogue, the catalogue files and full 4XMM documentation are available on the XMM-SSC webpages at




FITS files containing summary information about the observations used in the catalogue are also provided. FITS and CSV versions of the full 4XMM catalogue and a slimline version of the FITS file are also available for download at


The slimline version of 4XMM-DR11 has only one row per unique source (rather than per detection as in the main catalogue) and a reduced number of columns that essentially pertain to the unique source quantities.

Alongside the XSA user interface, 4XMM is also distributed through:

XCATDB: http://xcatdb.unistra.fr/4xmmdr11  

HEASARC: http://heasarc.gsfc.nasa.gov/W3Browse/xmm-newton/xmmssc.htm  

IRAP: http://xmm-catalog.irap.omp.eu/  


Yours sincerely,

XMM-Newton SOC