This image shows the density of observed objects in the third XMM-Newton Serendipitous Source Catalogue (3XMM-DR4), mapped in Galactic coordinates.
Sources in the 3XMM catalog are identified and isolated from serendipitous data recorded by XMM-Newton's EPIC X-ray cameras. In each of the 600-700 observations made each year, around 70 extra sources are captured in addition to the target object which usually only takes up a small fraction of the field of view. Covering observations between February 2000 and December 2012, the 3XMM catalog contains some 531,261 X-ray source detections relating to 372,728 unique X-ray sources.
The inset shows an expanded view of the small region indicated where the individual sources can be seen.
Image credit: ESA/XMM-Newton/EPIC/M. Watson (University of Leicester)
Note: For more information, see Latest XMM-Newton Catalogue Offers New X-Ray Vision.