XMM-Newton
Science Analysis System: User Guide
Next: 4.9.2 Removing Out-of-Time events from pn spectra
Up: 4.9 EPIC-pn Out-of-time events
Previous: 4.9 EPIC-pn Out-of-time events
4.9.1 Removing Out-of-Time events from pn images
The effect on images is shown in figure 24 (note the
arc-like structures due to single mirror reflections (stray light) at the top
left of the FoV).
Figure 24:
Effect of OoT events on
images: The upper left panel contains
a 2-10 keV band image of a pn observation of a bright source in full frame
mode with the OoT events visible as a strip running along the length of the
CCD. The upper right panel depicts the modeled OoT event distribution
whereas in the lower left panel these are
subtracted from the original image. The lower right panel shows the
distribution of cleaned events in the soft (0.2-2 keV) energy band for
comparison.
|
As mentioned in the previous section, 6.3 % of all events in a full-frame mode event file are
OoT events. Because the OoT event list contains the same number of events
as the original event list, the OoT image needs to be multiplied by 0.063
before subtracting it from the original image. Assuming that the user has
created two images (see § 4.7), one from the OoT and the
other from the "normal" event lists (named image_oot.fits and image.fits,
respectively), simple image arithmetics, using for example FTOOL
tasks, can be used to scale and subtract one image from the other
(details in the corresponding pages of the SAS Analysis Threads). This process
will remove from the image the strip associated with the OoT events.
Next: 4.9.2 Removing Out-of-Time events from pn spectra
Up: 4.9 EPIC-pn Out-of-time events
Previous: 4.9 EPIC-pn Out-of-time events
European Space Agency - XMM-Newton Science Operations Centre