XMM-Newton Serendipitous Source Catalogue: 2XMMi-DR3

The XMM-Newton Survey Science Centre is pleased to announce a further incremental version of the Second XMM-Newton Serendipitous Source Catalogue, 2XMMi-DR3.

The 2XMMi-DR3 catalogue is the fifth publicly released XMM X-ray source catalogue produced by the XMM Survey Science Centre (SSC) consortium on behalf of ESA. It follows the 1XMM (released in April 2003), 2XMMp (July 2006), 2XMM (August 2007) and 2XMMi (August 2008) catalogues: 2XMMp was a preliminary version of 2XMM. 2XMMi and 2XMMi-DR3 are incremental versions of the 2XMM catalogue.

With this increment catalogue, for the first time, as part of the catalogue naming convention we introduce the concept of a data release (DR) as a means of distinguishing between increments. This is being applied only to the 2XMM generation of catalogues. In this scheme (see following table), 2XMM is considered as DR1, 2XMMi as DR2 and the present catalogue as DR3.

Version nomenclature for 2XMM catalogues
Catalogue name     DR version     Full catalogue designation     Year released
2XMMp 0 2XMMp-DR0 2006
2XMM 1 2XMM-DR1 2007
2XMMi 2 2XMMi-DR2 2008
2XMMi-DR3 3 2XMMi-DR3 2010

The 2XMMi-DR3 catalogue has about 22% new detections as compared to the 2XMMi catalogue and is the largest X-ray source catalogue ever produced, containing ~ 3 times as many discrete sources as either the ROSAT survey or pointed catalogues. 2XMMi-DR3 complements deeper Chandra and XMM-Newton small area surveys, probing a much larger sky area.

The catalogue provides an effective dataset for generating large, well-defined samples of various types of astrophysical object, notably active galaxies (AGN), clusters of galaxies, interacting compact binaries and active stellar coronae, using the power of X-ray selection. The large sky area covered by the serendipitous survey also means that 2XMMi-DR3 is a rich resource for exploring the variety of the X-ray source populations and identifying rare source types.

The catalogue contains source detections drawn from 4953 XMM-Newton EPIC observations made between 2000 February 3 and 2009 October 8; all datasets were publicly available by 2009 October 31 but not all public observations are included in this catalogue. The catalogue contains 353191 X-ray source detections which relate to 262902 unique X-ray sources (covering an energy interval from 0.2 keV to 12 keV). About a third of the observations have features that may cause spurious detections (mainly the wings of bright sources and large extended emission), and it is strongly recommended to use a filter (either per source or per observation). In around 62% of observations, a detection could be identified as the intended target of the observation. The following table gives an overview of the statistics of the catalogue in comparison with the 2XMMi catalogue which was published in August 2008 and also 2XMM, relased in August 2007. The increment column is with respect to 2XMMi

  2XMMi-DR3 2XMMi 2XMM Increment
Number of observations 4953 4117 3491 836
Number of 'clean' observations (i.e., observation class < 3) 2789 2021 1754 768
Observing time 03-Feb-00 -- 08-Oct-09 03-Feb-00 -- 28-Mar-08 03-Feb-00 -- 31-Mar-07 1.5 years
Sky coverage, taking overlaps into account 504 sq.deg 420 sq.deg 360 sq.deg 84 sq.deg
Number of detections 353191 289083 246897 64108
Number of unique sources 262902 221012 191870 41890
Number of extended detections 30470 24533 20837 5937
Number of detections with time series and spectra 56017 44621 38320 11396
Number of variable detections 3177 2608 2307 569
Number of 'clean' detections (i.e., summary flag < 3) 284270 233698 199371 50572

The median flux in the total photon energy band (0.2 - 12 keV) of the catalogue detections is ~ 2.5 × 10-14 erg cm-2 s-1; in the soft energy band (0.2 - 2 keV) the median flux is ~ 5.6 × 10-15, and in the hard band (2 - 12 keV) it is ~ 1.4 × 10-14. About 20% of the sources have total fluxes below 1 × 10-14 erg cm-2 s-1.


The 2XMMi-DR3 catalogue, released on 2010 April 28th, is available in several formats:

2XMMi-DR3cat_v1.0.fits.gz FITS binary 279 MB MD5: 9f9afe43c7728d91fe17a9aa2281709d full binary catalogue; recommended for the experienced user and in-depth studies
2XMMi-DR3cat_v1.0.csv.gz CSV 366 MB MD5: c9c10aabc0f4f682b2965d9a74907edb full ascii catalogue
2XMMi-DR3cat_slim_v1.0.fits.gz FITS binary 32 MB MD5: 6aeebb99f2958f4479c3ad9db411e157 reduced binary catalogue, recommended for X-ray beginners and simple studies
2XMMi-DR3cat_slim_v1.0.csv.gz CSV 40 MB MD5: 8d35de42fde34299f8779090e252a656 reduced ascii catalogue

For convenience, there are suitable SQL CREATE statements available for use with a relational DBMS in order to load the data in CSV format:

The CSV file has nulls represented by two successive commas, compatible with Postgres and (probably) other DBMS.

The slimline version of the catalogue contains one row per unique source (while the the main catalogue has one row per detection) and thus has 262902 rows. There are 38 columns, essentially those containing information about the unique sources. The catalogue also contains a column with links to the LEDAS summary pages. In the case of sources with multiple detections the summary page of the best detection is selected (i.e., the detection with the largest exposure time, summed over all cameras), and the summary page gives cross-links to the other detections.

Two separate files are also provided (table below) which contain key details about the observations used in the construction of the 2XMMi-DR3 catalogue and information about the targets of the observations. See the list of observations and the list of target identifications for descriptions of the columns in each file.

2XMMi-DR3_summary.fits FITS binary 0.5 MB MD5: 603f23573f474ca207b6b67755d78952 Summary table of observations used in the catalogue
2XMMi-DR3_targets.fits FITS binary 0.8 MB MD5: 1c2bed03606fe87526b5a4c6aaa26537 Summary table of the targets of observations used in the catalogue

The following Web-based user interfaces will allow filtering and searching of the catalogue (and give access to all or selected associated data products):

The SSC Catalogue Home Page (this page), XSA, and HEASARC allow download of the catalogue file in (binary) FITS.


The User Guide for the 2XMMi-DR3 catalogue contains details of the catalogue production process and content. Here are quick links to

Nomenclature and Citation

Sources that originated in the 2XMM catalogue or were new in the 2XMMi catalogue will retain their IAU name nomenclature in 2XMMi-DR3, i.e. their IAU names start with a '2XMM' or '2XMMi' designator, respectively. Sources appearing for the first time in 2XMMi-DR3 are assigned an IAU name also starting with a '2XMMi' designator. The IAU name is provided in the catalogue. The correct, full nomenclature for a specific detection from these catalogues is the IAU name, followed by a colon and the detection identification number, that is:"2XMM Jhhmmss.sSddmmss:detid" or "2XMMi Jhhmmss.sSddmmss:detid".

The production and content of the 2XMM catalogue is described in detail in "The XMM-Newton serendipitous survey. V. The second XMM-Newton serendipitous source catalogue", M. G. Watson et al., A&A 493, p. 339. Note that there are no significant differences in the processing between the 2XMM, 2XMMi and 2XMMi-DR3 observations


The production of the 2XMMi-DR3 catalogue is a collaborative project involving the whole SSC Consortium:

The SSC acknowledges the use of the TOPCAT and STILTS software packages (written by Mark Taylor, University of Bristol) in the production and testing of the 2XMMi-DR3 catalogue.