XMM-Newton (or the High Throughput X-ray Spectroscopy Mission or
the X-ray Multi-mirror Mission, XMM)
is an X-ray space observatory launched by the European Space Agency
in 1999 and still active as of 3/2025. Instruments:
Among the surveys carried out are
XMM-LSS (for XMM-Newton Large Scale Structure) survey,
covering 11 square degrees,
the XMM Cluster Survey,
and the XMM-Newton serendipitous survey, detections from EPIC
camera observations. The latter's latest release (as of 4/2024)
is 4XMM-DR13, the "4" indicating it results from the survey's
fourth-generation X-ray source detecting process (pipeline).