The task takes as input a science EPIC event list. This file will be used as a skeleton (keywords, EXPOSUXX and GTIs extensions) to create the associated QPB file. It also uses the Attitude History file and the SAS ODF environmental variable from the science exposure to properly project into sky-coordinates the events that will make the associated QPB file.
As the associated QPB event list contains less photons than the observation science data, we apply an oversampling factor F, which takes F times more exposure time of FWC data than the original science observation. The user can define this oversampling factor using the parameter exposurefactor.
To generate the associated QPB event list, events from the CCF are selected based on proximity in time to the science exposure and around the central time of the exposure. An oversampling factor F, will take F times more exposure time to generate the associated QPB event list than the original science observation. Data accumulates CCD by CCD until the user’s oversampling exposure time is reached.
Once the FWC data have been accumulated, evqpb randomly distribute the FWC data events among the frames of the current science observation. Then, attcalc is run to re-project the events from detector coordinates to sky coordinates.
