XMM-Newton Science Analysis System


implotregions (implotregions-1.1.1) [xmmsas_20230412_1735-21.0.0]

Region files

The region files are also mandatory input files for this task. Any FITS file containing an extension REGION will be a valid region file. However the best candidate for region file is the spectrum file produced by SAS. Those spectra FITS file contain an extra extension with the REGION used to extract such a spectrum. The REGION extension has to be a table with the following 4 columns: SHAPE, X, Y, R, where SHAPE is the region shape (CIRCLE for sources and CIRCLE or ANNULUS for background) and X, Y is the position of the region in Sky X/Y coordinates. R is the radius of the region in arcsec.

In order to draw the extraction region of the source and the selection background, two region files have to be included at the command line. One for the source (srcregfile) and the other one for the background (bkgregfile). Besides the background region, the background region file usually contains the contaminating sources which were excluded in the background estimate.

The extraction regions will appear in the resulting thumbnail image as follows:

- Source: white solid line

- Background: white dashed line

- Background contaminating sources: solid red lines