combimage combines the various EPIC exposure images from a single observation (ObsID), including images from multiple exposures, into single count, exposure, model particle background, soft proton background, and model solar wind charge exchange (SWCX) background images.
combimage compensates for the inclusion of observations with
different filters in the mosaic. It uses the results of PIMMS with
the assumption of a power-law spectrum with photon indices (alpha) of
2.4, 1.7, and 1.0, and absorption of
H I cm
. The user enters a value for
alpha between 1.0 and 2.4 where 1.0 will select the hard spectrum, 1.7
selects the medium spectrum, and 2.4 selects the soft spectrum.
Intermediate values will produce a linear scaling between the two
nearest spectra. The exposure image is then scaled by the ratio of
the model count rates for the MOS2 medium filter versus the thin or
thick, making the resultant image appropriate for the MOS2 medium
filter.
Warning and requirements: combimage was part of the singular esas package integrated into SAS but was made a standalone task for SAS-21. It is limited to work within the esas data reduction scheme. This is especially true wrt to the names and structures of the input files. In particular, combimage assumes that another tasks from the package, mosspectra, pnspectra, mosback, pnback, rotdet2sky, and possibly proton and swcx have been successfully run for the exposures to be used.
