How was the SASS .MOI file (the modified instrument map used to construct the SASS _MEX.FITS exposure map file) created?
Originally, the .MOI file was constructed from ground-based calibration data, and was valid for energies of about 1 kev. Since sometime in 1992, SASS has used a new .MOI file, constructed from sky survey data. This (we believe) was created in much the same way as Steve Snowden's maps, and covers the channel range from 42 to 131.
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