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P. Ratzlaff, B.J. Wargelin, J.J Drake, C.O. Johnson, D. Pease (Harvard-Smithsonian Center for Astrophysics), D. Dewey (Massachusetts Institute of Technology Center for Space Research)
Prior to launch, the Chandra X-ray Observatory underwent comprehensive calibration at the NASA X-ray Calibration Facility (XRCF, Marshall Space Flight Center). We present results of a final analysis of these calibration data for the Low and High Energy Transmission Gratings (LETG and HETG), as well as for the High Resolution Mirror Assembly (HRMA).
Detailed source spectra for each combination of x-ray source anode and filter were derived from imaging-detector/grating data. Results from simulations using the MARX ray-trace suite were then used to account for finite-aperture-size and window-bowing effects in the focal-plane flow proportional counters (FPCs) used to collect the grating efficiency data. After these adjustments were applied and the relative strength of each line within the complex was determined, the FPC JMKMOD model for the XSPEC spectral fitting program was used to fit data from focal-plane and beam-monitor detectors. In this way, best-fit parameters for the different instrument configurations were derived, yielding measurements of the HRMA effective area and LETG and HETG diffraction efficiencies over a broad spectral range. Although measurements of 0th and 1st order grating efficiencies comprise the bulk of the data, extensive information was also obtained on higher-order diffraction.
P. Ratzlaff, B.J. Wargelin, J.J. Drake, C.O. Johnson and D. Pease were supported by Chandra X-ray Center NASA contract NAS8-39073.