HEAPOW: Keep Busy (2010 Dec 27)
ESA: XMM-Newton All Sky Slew ImageSatellite observatory time is very dear. Typically high flying observatories receive four or five times more requests for observations than they have time to observe, so there's great pressure to maximize observing time. There's also great reluctance to turn instruments off. When an observatory like the Chandra X-ray Observatory or the XMM-Newton X-ray Observatory has observed one object fully, and the telescope moves silently to the next project, in most instances the telescope operators will continue to observe during the slew. These "slew observations" build up narrow strips of observations along the celestial path of the telescope. Eventually these strips build up into significant sky coverage. The image above, for example, shows in galactic sky coordinates the coverage of the sky obtained by the XMM-Newton observatory during its first nine years of operation. Nearly half the entire sky is covered, and this "demi-sky survey" (consisting of 836 scans) reveals known astrophysical objects like the Cygnus Loop, the bright Vela supernova remnant, Sco-X1, the Large and Small Clouds of Magellan, the Virgo Cluster, and other large-scale structures.
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