XMM-Newton slew catalog
Astronomical instruments are expensive. Satellites are even more expensive. Optimizing the data taking and making the most out of the available observations is therefore an important process. The XMM-Newton X-ray satellite has illustrated this by publishing its second "Second Slew Survey Catalog". Typically ground and space borne observatories perform pointed observations of a pre-defined list of interesting regions and objects. The time spent moving the instrument from one direction to the next is usually called dead-time and disregarded. The ESA led XMM-Newton satellite continues data taking during the slewing and the team managed to carefully analyse the obtained data and extract very useful information. The resulting source catalog contains ~70.000 sources detected during the slewing and represents ~10% of all XMM detected sources. The analysis add data to some old friends of mine: star-and-black hole binary systems like GRS 1915+105 and V 4641 Sgr (see Microquasars for a recent H.E.S.S./RXTE analysis of these objects).
Sidenote: The operation mode of current TeV gamma-ray Cherenkov telescopes does not allow for data taking during slewing (the cameras are switched off in order to prevent damage due to bright stars passing through the field-of-view). On the other hand, the upcoming Cherenkov Telescope Array (CTA) will be able to continuously take data and one can imaging a future "CTA Slew Survey Catalog"...
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