Increases scientific return from Chandra by providing a public database of optical multicolor imaging well-matched in depth to selected Chandra X-ray fields. Uses only public archival Chandra data, or proprietary data offered by explicit consent of the GO/GTO . ... to GO/GTOs immediately after images of their fields are reduced, if our request for early access to X-ray data is granted 1 . ... that are not intended as serendipitous survey fields (e.g. Chandra deep survey fields) . ...
... The Swift X-ray Cluster Survey (SXCS) is an ongoing project aimed at finding serendipitously galaxy clusters in the Swift X-ray Telescope (XRT) archive. ... ROSAT . ... 600 km Here SXCS is compared with other X-ray cluster surveys based on Chandra or XMM data (please refer to Tundo et al. 2012 for detailed discussion). ... We are currently working to a second data release, based on a larger set of XRT fields, and on the use of a Voronoi-based algorithm "EXSdetect" tailored to the XRT data. ...