This plot monitors the persistence in IFS background calibrations which can be generated by previously acquired IFS optical distortion calibrations. These optical distortion calibrations can leave a pinhole slice pattern in the IFS background pipeline product.

The QC parameter is simply: the median counts in the pipeline product in a window P = [770, 130 --- 850, 1440] minus the median counts in window B = [640, 1470 --- 720, 1570].

Window P (pinhole) is the area where the pinhole slice pattern can show up and window B (background) is the area off the pinhole slice pattern areas on the detector.

The absolute persistence value in ADU is divided by the DIT and multiplied by 60 to represent the ADU difference for 1 min exposure time. Because of the linear dependence to the IFS optical bench temperature relation, this value is also divided by the T_bench value, so it corresponds to 1 deg C. This finally normalized persistence value is monitored.