XMM-Newton Science Analysis System: User Guide

4.7.6 Analysing EPIC images

There are a set of routines in SAS which are useful for processing regions within images. These routines return information which can be used for further processing.

• eregionanalyse: Given an EPIC image, this task performs a source region optimization. The image should be in detector or sky (X/Y) coordinates, like standard images produced by evselect or xmmselect and the pipeline. Spatial regions may be entered in detector, sky (X/Y) or celestial (RA, DEC, FK4 2000) coordinates. eregionanalyse returns amongst other information, source centroid, optimum extraction radius, source counts, count rate, etc... All these values are written to standard output.

• psfgen: This task generates the point spread function from a calibration file provided an EPIC image or a defined region within the image.

• eradial: Is a task that allows to extract a radial profile of a source in an EPIC image from the field of view of an observation and compare it with the nominal point spread function from a calibration file. This allows to test whether a source is extended or not by inspecting the provided output; the radial profile, the theoretical point spread function at that position in the image and at that energy, and the best fit normalisation of that PSF to the actual radial profile data.

More information on these tasks can be found at the SAS tasks documentation web pages.