XMM-Newton Science Analysis System: User Guide

6.3.1 Data preparation: tracking correction

The same tasks used in the image chain are repeated here:

• omprep (step1). The task omprep does not generate final data products but only intermediate files. OM images, tracking history files and fast mode files if any, are copied into temporary files. Further information is added via keywords. Intermediate products are generated, which carry information extracted from the tracking history file. If no tracking history file was produced, these are generated on the fly assuming perfect stable pointing. Tracking history data can be missing if no suitable tracking stars were available during observation. This occurs frequently when UV filters are used.

• omdrifthist (step2). This task creates the TSHPLT.ps file (TSHPLT.PDF in the pipeline processing), which provides an overview of the pointing stability during an exposure. The file contains diagrams illustrating the absolute and incremental OM drift.

• omthconv (step3). This task creates the TSTRTS.FIT file, which contains the tracking star time series, i.e the average count rate (cts/s) per tracking frame for each tracking star.