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As described in section 6.2.1 an absolute effective area
measurement requires a normalization
to the X-ray flux density at the HRMA entrance. For DCM measurements in
the 3 to 10 keV range the X-ray beam incident on the HRMA was measured to be
non-uniform at approximately the 10% level.
We have estimated the incident flux by taking the average of the
four BND's at the HRMA location. Higher spectral orders from the DCM
are not expected to be present in the 3 to 10 keV range.
The quantum efficiency values and open areas for the BND counters were
provided by SAO.
For the present reduction of the BND spectra we have chosen a
region of interest approach. The extracted X-ray line count rate
is divided by the quantum efficiency of
the BND at the X-ray line energy.
Please address comments and questions to Dr. John Nousek ( nousek@astro.psu.edu )