XMM-Newton Science Analysis System


epexposure (epexposure-0.16) [xmmsas_20230412_1735-21.0.0]

MIP dependent quadrant livetime factor FC1

A counter in the AUX file is the Discarded Line counter NDSCLIN (see Table 1). This value comes per quadrant and per $n$ CYCLEs: In case of full frame, extended full frame and large window modes NDISCLIN gives the number of discarded columns. The corresponding livetime factor is

  $$FC1 = 1 - {\rm NDISCLIN}/(64 \cdot \char93 CCD \cdot {\rm An\_MAXFRC)}\;.$$ (1)

The factor $\char93 CCD$ gives the number of active CCDs in the quadrant under consideration. Under normal circumstances this should be 3 for the above three imaging modes. To check for possibly switched off CCDs, however, one needs to extract the counter An_CCDSEL (see Table 1).

In case of small window, timing, and burst mode there is only one active CCD. For these modes the onboard MIP rejection is switched off (all events transmitted, NDSCLIN = 0) and the equation reduces to $FC1 = 1$.