New versions of the XMM-Newton Serendipitous Source Catalogues: 4XMM-DR12 and 4XMM-DR12s
A new version of the XMM-Newton EPIC Serendipitous Source Catalogue, 4XMM-DR12, has been 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-DR11. 4XMM-DR12 includes 939270 X-ray detections which relate to 630347 unique X-ray sources from 12712 observations that were public by the 31st December 2021. 4XMM-DR12 covers a total sky area, with at least 1 ks exposure, of 1283 square degrees if overlaps are taken into account, where some regions of the sky have been pointed as many as 84 times. Around 9% 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 the detection catalogue 4XMM-DR12, we release the stacked catalogue 4XMM-DR12s, created from overlapping observations. Stacking results in better source parameters, higher sensitivity, and direct access to measures of long-term flux variability. 4XMM-DR12s is built from 1620 groups drawn from 9355 observations. Each group includes between 2 and 372 observations. Stacked source detection is performed on all overlapping exposures of reasonable quality. For the first time, parameters from PSF photometry on lower-quality exposures are provided as well. 4XMM-DR12s contains 386043 sources, of which 298626 have several contributing observations. It reaches a median depth of ~2.5E-15 and ~6.8E-15 erg/cm2/s in the soft (0.2-2 keV) and hard (2-12 keV) X-ray band, respectively. 6868 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 ( http://xmmssc.irap.omp.eu/ ) at:
http://xmmssc.irap.omp.eu/Catalogue/4XMM-DR12/4XMM_DR12.html
and
https://xmmssc.aip.de/cms/catalogues/4xmm-dr12s/
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
http://www.cosmos.esa.int/web/xmm-newton/xsa
The slimline version of 4XMM-DR12 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/4xmmdr12
HEASARC: http://heasarc.gsfc.nasa.gov/W3Browse/xmm-newton/xmmssc.html
and https://heasarc.gsfc.nasa.gov/W3Browse/xmm-newton/xmmstack.html
IRAP: http://xmm-catalog.irap.omp.eu/