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.