The 4XMM-DR14s catalogue of serendipitous sources from overlapping XMM-Newton observations

The catalogue is compiled from all groups of overlapping public XMM-Newton observations and provide information on source positions and source parameters like fluxes in the XMM-Newton standard energy bands, hardness ratios, quality estimate, and information on inter-observation variability. The parameters are directly derived from the simultaneous fit, and, wherever applicable, additionally calculated for each contributing observation. For lower-quality exposures, not used in source detection to ensure the detection quality, the source parameters are derived from subsequent PSF photometry. The catalogue aims at exploring the multiply observed sky regions and exploit their survey potential, in particular to study the long-term behaviour of X-ray emitting sources. It thus makes use of the long(er) effective exposure time per sky area and offers the opportunity to investigate flux variability directly through the source detection process. More details on the catalogue and its production are provided at https://xmmssc.aip.de