xspec FITS response matrix format. (See Goddard Office of Guest Investigator Programs Calibration Memos CAL/GEN/92-002 & CAL/GEN/92-002a available in Postscript format from cal_gen_92_002.ps and cal_gen_92_002a.ps .
This matrix includes only the CCD spectral redistribution for a typical front-illuminated detector, and does not incorporate detector quantum efficiency, UV/optical blocking filter transmission, or AXAF telescope effective area. The matrix is based on subassembly calibration measurements made at MIT CSR with flight detectors and engineering model detector electronics. It is intended to represent the spectral response of any of the front-illuminated flight detectors when 1-, 2- and 3-pixel events are selected with a split-event threshold of 15 electrons. The FITS header comment fields provide additional details about the matrix generation process.
When combined with ancillary response functions (arf) representing the HRMA effective area, ACIS optical blocking filter transmission, and CCD detection efficiency as functions of energy, the matrix should be useful for simulating ACIS observations with front-illuminated CCDs for purposes of proposal preparation.