XMM-Newton Science Analysis System


epfast (epfast-0.7) [xmmsas_20230412_1735-21.0.0]

Introduction

The epfast task is designed to correct for a CTI effect which has been seen in EPIC-pn fast mode (timing, burst mode) data. Firstly, it finds the count rate of electrons which have been recorded at a given time in a given column of the CCD. It then applies a formula to this rate to calculate a correction value for the CTI.

  $$Eout = Ein / (a0 * rate^{a1} + a2)$$ (1)

where Ein is the initial PI value of the event, Eout is the final PI value and rate is the number of electrons per second observed in a particular column at a given time. The coefficients, a0, a1 and a2 have been calibrated using in-orbit data and are different for Timing and Burst mode. The number of electrons is derived from the total PI charge deposited on the column at that time.