XMM-Newton Science Analysis System


multixmmselect (xmmselect-2.67) [xmmsas_20230412_1735-21.0.0]

OGIP spectral products

In multixmmselect, the generation of spectral products goes one step beyond, allowing the generation of:

• OGIP spectrum for selected source region
• OGIP spectrum for selected background region
• Redistribution Matrix File (RMF) corresponding to source spectrum
• Auxiliary Response File (ARF) corresponding to source spectrum

for more than one EPIC event list simultaneously. To do this, once the OGIP spectral button is pressed in multixmmselect, a call to multiespecget is triggered. This task calls especget as many times as input files have been introduced.

The only differect in terms of behavior with respect to the OGIP spectral product generation feature in xmmselect, is the creation and propagation of the source and background region in sky coordinates (RA,DEC), instead of the standard camera coordinates system (X,Y) used by xmmselect.

The primary input to multiespecget is a mosaic image made of several EPIC event files and two spatial selection expressions, one indicating an extraction region around the point source of interest and a second one for the source-free background region. These can be generated with multixmmselect in a convenient manner:

1. create a mosaic image in sky coordinates as described above
2. when the image is displayed in Ds9 define a circular region around the source of interest
3. make another (not necessarily circular) region that shall comprise only background events. In order for multixmmselect to distinguish the source from the background region, the latter must be assigned in Ds9 the attribute Background. To do that, double click on the region marker and in the upcoming dialogue box select “Property” and “Background”. When done, the border line style should change from solid to dashed.
   Be sure that the “exclude” regions has not been selected.

4. click on OGIP Spectral Products. At this point multixmmselect will read the two regions from Ds9 and perform some basic checks for correctness (e.g. there is exactly one source and one background region). In case this fails, an error messages with suggested actions will be presented. If the two regions are successfully read, multiespecget will be called with the necessary inputs. In this first version of multixmmselect, the optional optimization step have been disabled.

Please note that the production of one single RMF with especget is a computationally intensive task and can take several tens of minutes on a moderately loaded workstation. Now, with multixmmselect, several RMFs files can be automatically generated, therefore this process can take longer to complete.