XMM-Newton Science Analysis System: User Guide

6.3 Description of the OM fast mode data processing chain omfchain

The example input dataset given in Table 10 contains also fast mode data files. To process them with SAS, the task omfchain has to be used. As for image data, the input data do not change through the fast mode chain.

The process is similar to the one for image data. It can be followed in figure 45. For each fast mode window of the different exposures in the observation (ODF) there will be

• Data preparation: tracking correction. The tracking data, which are common for image and fast mode data, are treated to derive the corrections to be applied to the events detected in an exposure.

• Event selection and corrections. The event list file is scanned to find the photon events. Then tracking and flat field corrections are applied.

• Source detection and astrometry. The source is located within the fast mode window (eventually more than one source) and astrometry conversions are applied.

• Light curve. Count rates are derived for the source(s) and the background. Then a light curve is produced giving the net countrate as a function of time for each fast window in each exposure. A graphical output is produced as well. In the future all light curves obtained with the same OM filter will be merged.

Figure 45: SAS processing chain for data acquired in the OM fast mode.