The ASTERIX system uses a detector matrix, Rootname_DRPM.SDF, which contains the relative contributions of 729 trial energies in each of the 256 corrected pulse height bins. This needs to be multiplied by the effective area at each energy before it can be used in a spectral fitting program. The effective area depends on the position of the source in the field of view. ASTERIX writes an array containing the effective area at each of the 729 trial energies for the position of a given source into the source file. (Actually in a structure MORE.ASTERIX.INSTRUMENT.ENCORR.DATA_ARRAY). This is then multiplied by the detector matrix prior to spectral fitting. So the detector response is unique to each source and hence is stored in the datafile itself. This can make each spectral datafile large, especially if the full 256 bin resolution has been used.
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