The XMM-Newton Serendipitous Sky Survey

The 2XMM catalogue, from the XMMNewton Serendipitous Sky Survey, has recently been released. Containing almost 200 000 sources, from around 360 square degrees of the sky covered by XMMNewton so far, this is the largest X-ray catalogue. The combination of large survey size and sensitivity makes it invaluable for generating large, well-defined samples of various types of astrophysical object, exploring the overall properties of various X-ray source populations and an especially powerful resource for the discovery of rare and unexpected objects.