Date: Tue, 23 Jun 1998 16:33:41 -0400 From: Ian Evans Subject: AXAF CAT telecon: Wed., Jun 10, 1030 EDT To: axaf_cat@alph.msfc.nasa.gov ... Here are the best estimate measurements of the mean HSI QE, on-axis, normal incidence to the plates (ie 6 deg to the pore axis). The measurements were obtained relative to an FPC. QESAO is the QE measured at the SAO XPF, and was obtained with a Manson source with HV = 2 x line energy, and typically a 1 mfp filter. QEXRCF was obtained earlier at the XRCF as part of the flat fielding, with the EIPS, HV = 4 x line energy, and typically a 2 mfp filter. QEXRCF is what was published in the SPIE proceedings, except that the FPC reference QE has been corrected for the best fit model to FPC_X2 rather than the pre-XRCF generic FPC QE used as a reference in the SPIE paper. The QESAO is referenced to the best fit model to the FPC_HB QE used at the SAO pipe. The statistical errors are < 0.5 %. As you can see, the agreement varies from pretty good to pretty awful , depending on energy (note Fe L especially). This may well be due to the fact that the HSI is not energy sensitive, and so the entire spectral shape, which was different between XRCF and SAO, is relevant. The next step is to take the individual measurements and fold the observed spectra back through the FPC QE to derive the incident spectrum as a function of energy, and use these numbers as a starting point to iteratively compute the QE as a function of energy. E QESAO QEXRCF 0.183 0.185 0.153 0.277 0.236 0.223 0.525 0.126 0.705 0.184 0.0784 0.930 0.0951 0.0702 1.254 0.0517 1.486 0.0594 0.0430 2.29 0.0476 0.0307 3.44 0.0445 4.51 0.0363 6.40 0.0413 0.0684 8.05 0.0832 As I do not work for MST any more, I can only work on this and other HSI calibration issues on an "as time permits" basis. As a result, I also have been unable to attend the CAT telecons in recent months, since they conflict with a weekly meeting that I attend as part of my ASC position. Cheers, Ian