Data Processing

Event finding was performed on each raw data frame with an event threshold of 38 ADU for the front illuminated devices and 20 ADU for the back illuminated devices. The split threshold was 13 ADU for all measurements. The event finding was performed using an IDL script which output an ARV format event list. Each ARV format event list was then summarized using an IDL script. This IDL script fit a gaussian to the main peak of the spectrum. Only events in ACIS grade bit map 0x1d05 0x0047 0x0004 0x0047 0x1133 0x0003 0x1100 0x0000 0x1d04 0x0000 0x0004 0x0000 0x0000 0x0003 0x0000 0x0000 (ASCA grades 02346) were considered. Using the fit parameters, the position of the peak, width of the peak, and total number of counts under the peak are determined assuming the line response is Gaussian. All of these values are written to a text format file. Finally, the text format summary files are read by another IDL script which uses the counts per frame versus energy to correct for pileup, the filter efficiency versus energy to correct for filter effects, and the CSR calculated s2 quantum efficiency. This IDL script also reads in a SSD 5 flux rate.