Depth and Size of X-Ray Surveys

Illustration comparing different X-ray surveys in terms of total area covered on the sky and the depth of the detected sources. The 2XMM catalogue is the largest X-ray survey to date, covering in total ~360 square degrees on the sky. The median flux of the detections over the covered energy band of 0.2-12 keV is ~2.5 × 10-14 erg/cm²/s. Copyright: Prof Mike Watson, XMM-Newton SSC, University of Leicester, UK