(Based on analysis by Bev LaMarr)
Data: Raw Mode, ObsID 62273, external calibration source, -120 C
49012 events, 916 telemetered frames of 10 sec each, 20 x 1024 pixel strip
Of the grades currently rejected onboard, only ACIS grade 66 has spectral features that correspond to the Mn-K lines in the external calibration source.
Statistics of Flight Rejected Grades
|ACIS Grade||ASCA Grade||Count rate (cts/sec/CCD)||Percent of total events||Spectrum|
|ACIS Grade||ASCA Grade||Percent of total events||Rejected?||Spectrum|
The grade 66 events include some X-rays from the cal source as can be seen by the small Mn-K peak in the spectrum of these events. An estimate of the number of events in the Mn-K peak is 611 out of 1869 total events (between 1175 and 1625 ADU). This corresponds to a rate of 3.8 cts/sec/CCD in X-rays and 7.8 cts/sec/CCD in background events from the grade 66 events.
Applying the same criteria to G02346 data, there are 9057 counts in the Mn-K peak (55.9 cts/sec/CCD). Assuming that g66 is the only non-G02346 grade that includes substantial X-rays, approximately 6% of the X-ray events at Mn-Ka are being lost to g66 events.