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Timing

 

The dead time of the PSPC due to X-ray events was determined between s and s per event depending on pulse height; the dead time due to particle events is about s. For ``typical'' ROSAT observations, i.e., observations with the total (accepted) X-ray event rate being less than  counts s , deadtime will be almost exclusively caused by the count rate due to particle background events; for particle background rates of 100 counts s , the dead time is percent and for the maximal background rate of 400 counts s , this increases to percent.

While each recorded PSPC event is time-tagged, the electronics allows only an effective resolution of s; this accuracy applies only to the relative arrival times of recorded events. The accuracy of absolute timing with respect to UT is on the order of a few milliseconds.