Mosaic mode XMM-Newton image of the entire XMM-BCS survey field
This XMM-Newton image, obtained using the new mosaic mode of observations, shows the extent of the XMM-BCS survey. The survey targeted a patch of the sky of 14 square degrees, about 70 times the area of the full Moon - the angular size of the Moon is also shown for comparison.
The green circles, with a radius of 4 arc minutes each, mark the positions of the two galaxy clusters SPT-CL J2332-5358 and SPT-CL J2342-5411. More than 100 other galaxy clusters have been found in this field.
This false-colour image was constructed from X-ray surface brightness images in 3 bands: 0.3-0.5 keV (red), 0.5-2.0 keV (blue) and 2.0-4.5 keV (green), respectively. Most of the - over 3000 - point sources visible in the fields are Active Galactic Nuclei (AGN).
Regions A, B and C mark the three large fields covered by mosaic mode observations, each amounting to about 2.7 square degrees, for a total of about 8 square degrees. Each of the three mosaics consists of 19 stable pointings, each with a 3.5 ks exposure, and the slews between them, for a total time of about 90 ks per mosaic.
Region F covers about 6 square degrees and identifies the deeper core of the survey, consisting of 42 individual and partially overlapping pointings; each pointing corresponds to a 12 ks long exposure.
As a result of the new mosaic observing mode, it has been possible to survey an area of the sky (regions A, B and C) larger than the original survey area (region F) in only a fraction of the time that was required to observe the latter using the standard mode.