AXAF high-resolution camera (HRC): the challenge of calibration

The High Resolution Camera (HRC) is a microchannel plate based, photon counting, imaging detector for the Advanced X- ray Astrophysics Facility (AXAF) that will be placed in a high earth orbit scheduled for launch in December, 1998. An end-to-end calibration of the HRC and the AXAF High Resolution Mirror Assembly was carried out at the Marshall Space Flight Center's X-ray Calibration Facility. This activity was preceded by various subsystems level calibrations of the detector components, but only through complete end-to-end testing was it possible to fully study the instrument and identify areas for improvement. As a result, several modifications were made to the HRC. These were followed by a series of flat field calibrations used to 'correct' the end-to-end results for flight.