The SSC has been responsible, on behalf of ESA, for the construction of the XMM-Newton Serendipitous Source Catalogues. Since the first version of the EPIC X-ray catalogue 1XMM, released in April 2003, there have regular incremental and major updates: 2XMMp (an interim version of the more complete and extensive 2XMM catalogue) in July 2006, 2XMM in 2007, and two increments to 2XMM, i.e. 2XMMi in August 2008 and 2XMMi-DR3 in April 2010. 3XMM-DR4 was made public in July 2013, and incremental versions, 3XMM-DR5, in April 2015, 3XMM-DR6, in July 2016, 3XMM-DR7, in June 2017, 3XMM-DR8, in May 2018 .
Along 2019 all archival data were reprocessed following a major revision of the processing software and data products and a new version of the catalogue was released in December 2019 as 4XMM-DR9. A catalogue of sources detected after stacking different observations on overlapping sky regions was release (4XMM-DR9s). Incremental updates of both pointed and stacked catalogues were released in December 2020 as 4XMM-DR10 and 4XMM-DR10s.
Production of the catalogues involves collation of archived, processed products (or a bulk reprocessing of all the data when major software and calibration changes have accumulated), the selection of suitable public datasets, screening and verification of the X-ray detections and associated data products, compilation of the catalogue from the source lists of the individual observations and auxiliary information, scientific validation of the catalogue, and making the catalogues and documentation publicly available to the scientific community, in close collaboration with ESA. A number of added-value products, such as image thumbnails and summary web-pages for each source are also generated separately. Each catalogue release uses as many of the publicly available datasets as possible, though some observations are excluded for various reasons, e.g. very low exposure, or cases with processing or pathological problems.