3XMM-DR4

One of the primary roles of the XMM-Newton Survey Science Centre (SSC) is to provide, on behalf of the European Space Agency (ESA), regular public releases of the XMM-Newton serendipitous survey source catalogues.

This page provides information on the latest version of the XMM-Newton catalogue, 3XMM-DR4. The 3XMM-DR4 catalogue is the sixth publicly released XMM-Newton 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), 2XMMi (August 2008) and 2XMMi-DR3 (April 2010) catalogues: 2XMMp was a preliminary version of 2XMM. 2XMMi and 2XMMi-DR3 were incremental versions of the 2XMM catalogue.

The motivations for creating 3XMM-DR4 are threefold:

1 - A substantial (~50%) increase in the number of public observations that can be included

2 - Significant improvements to the XMM-Newton Science Analysis Software and developments with the calibration

3 - The opportunity to advance the scientific quality of the catalogue through enhancements to the processing algorithms. The key science-driven gains include:

i) Improved source characterisation and reduced spurious source detections

ii) Improved astrometric precision of sources

iii) Greater net sensitivity for source detection

iv) Extraction of spectra and timeseries for fainter sources, with improved signal-to-noise

Taken together, these elements yield a catalogue that is about 50% larger than its predecessor, 2XMMi-DR3, and is, overall, of better quality and accuracy.

By number of sources, 3XMM-DR4 is the largest X-ray source catalogue ever produced. 3XMM-DR4 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 3XMM-DR4 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 7427 XMM-Newton EPIC observations made between 2000 February 3 and 2012 December 8; all datasets were publicly available by 2012 December 31 but not all public observations are included in this catalogue. The catalogue contains 531261 X-ray detections which relate to 372728 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, based on the summary flag column, or per observation, based on the observation class column). The following table gives an overview of the statistics of the catalogue in comparison with the 2XMMi-DR3 catalogue.

The median flux in the total photon energy band (0.2 - 12 keV) of the catalogue detections is ~ 2.4 × 10^-14 erg cm^-2 s^-1; in the soft energy band (0.2 - 2 keV) the median flux is ~ 5.7 × 10^-15, and in the hard band (2 - 12 keV) it is ~ 1.3 × 10^-14. About 20% of the sources have total fluxes below 1 × 10^-14 erg cm^-2 s^-1.

Access

The 3XMM-DR4 catalogue, released on 2013 July 23^rd, is available in several formats:

Please read the Watchouts section before using the catalogues.

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

• load_3XMM_DR4cat_v1.0.sql
• load_3XMM_DR4cat_slim_v1.0.sql

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 372728 rows. There are 44 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.

A separate file is also provided (table below) which contains key details about the observations used in the construction of the 3XMM-DR4 catalogue. See the list of observations for a description of the columns in the file.

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

• XSA at ESA's XMM-Newton SOC
• LEDAS at the SSC institute, University of Leicester
• XCAT-DB at the SSC institute, Observatoire Astronomique, Strasbourg
• Browse or Browse 3XMM-DR4 at HEASARC NASA GSFC

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

Documentation

The User Guide for the 3XMM-DR4 catalogue contains details of the catalogue production process and content. Here are quick links to

• the description of the columns in the catalogue,
• the list of observations used to compile the catalogue,
• the table of energy bands used for the catalogue.

Watchouts

1) Shortly after release, an error was noted with the vignetting values in the 3XMM-DR4 catalogue (and the OMSRLI and OBSMLI pipeline product source lists), arising from a bug in the emldetect SAS task. For a given detection (row) in the catalogue, all values of the vignetting for a given instrument (i.e. columns <instrument>_<band>_VIG where <instrument> is PN, M1 or M2 and <band> is the energy band (1 to 5)) are identical and equal to the vignetting value at the source position, but for an energy of 0 keV rather than the intended mid-band energy. It should be emphasised that this error in the vignetting values does not affect the count-rates (or fluxes) - these are computed using the exposure maps in which the vignetting corrections, based on the correct band energies, are embedded. The error only affects the quoted vignetting columns in the catalogue and the corresponding entries in the OMSRLI and OBSMLI pipeline product files

A version of the catalogue with correct vignetting columns will be made available shortly. Corrected versions of the OMSRLI and OBSMLI source list files will also be generated and re-ingested in to the XSA in due course.

2) It has been established that the ODFs of a subset of the mosaic-mode observations have been incorrectly split in to sub-pointings. Eight parent observations (involving 63 sub-pointings and 3943 detections in the 3XMM-DR4 catalogue) are known to show clear temporal overlaps of data between sub-pointings, where there should be no such overlap. In these cases all sub-pointings and instruments are believed to be affected. A further ten parent cases (involving 26 sub-pointings, of which 19 (involving 975 detections) are in the 3XMM-DR4 catalogue) are known in which some of the sub-pointings are affected and in these, only MOS1 and/or MOS2 data are impacted. The cause appears to be related to incorrect time-tagging of events due to telemetry gaps, which the splitting process handled incorrectly.

These 18 mosaic-mode parent problem-case observations (encompassing 89 sub-pointings) are listed here. Two comma-separated-variable format files, one for the cases where all data are affected and one for cases where some data are affected, are provided which contain the DETID, OBS_ID, RA, DEC and INSTRUMENT(s) affected for detections from the relevant problematic sub-pointings.

In the cases where all data are affected, this problem has most obviously manifested itself in (visibly) erroneous timeseries for detections from the affected sub-pointings. However, it is important to emphasize that in these cases all the data/products are unreliable. For those cases where only some of the data are affected, the SOC believe that only timeseries data/products are affected and only for the MOS1 and/or MOS2 instruments.

When a full analysis of the problem is completed, the SOC and SSC will consider what corrective action may be applied in terms of the processed data, the catalogue and the associated data products. In the meantime, users are advised to disregard all data/products of detections from the observations where all data are affected (and any unique source data that involve them). Users should also disregard timeseries from those cases where some of the data are affected, though it is advisable to treat other products/data from these cases with caution too.

Nomenclature and Citation

With the new, 3XMM-DR4 catalogue, IAU name nomenclature includes the designator, 3XMM. The IAU name is provided in the catalogue. The correct, full nomenclature for a specific detection from the catalogues is the IAU name, followed by a colon and the detection identification number, that is:"3XMM Jhhmmss.sSddmmss:detid".

Credits

The production of the 3XMM-DR4 catalogue is a collaborative project involving the whole XMM-Newton SSC Consortium:

• University of Leicester, UK
• Mullard Space Science Laboratory, University College London, UK
• Max-Planck Institut für extraterrestrische Physik, Germany
• Leibniz-Institut für Astrophysik, Potsdam (AIP), Germany
• Service d'Astrophysique, CEA/DSM/DAPNIA, Saclay, France
• Institut de Recherche en Astrophysique et Planetologie, Toulouse, France
• Observatoire Astronomique de Strasbourg, France
• Instituto de Fisica de Cantabria, Santander, Spain
• Osservatorio Astronomico di Brera, Milan, Italy

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 3XMM-DR4 catalogue.

Last Updated: 6-Feb-2014