XMM-Newton Science Analysis System: User Guide

4.11.5 Background

By default the slew processing does not include any filtering for periods of high background. Such a filtering would lead to blank regions in the slew images. It is has been seen that strong background flares lead to a section of the slew being relatively bright. At first sight, this is indistinguishable from a slew image of a large Supernova remnant (SNR). Usually photon energies can be used to make the distinction. High background usually leads to an excess at high energies ($>$2 keV) whereas SNR are usually brightest at energies below 2 keV.

In high background regions, source search algorithms will tend to find a large number of spurious sources.