This is a development model for the high resolution X-ray imager that was eventually flown on the High Energy Astronomical Observatory-2 (HEAO-2) spacecraft. It is called a "brassboard" to denote the fact that it represents a development stage more advanced that the initial breadboard but short of the protoype for the final instrument. The critical elements are packaged as they will be in the flight unit while less critical elements are present in more rudimetary fashion. HEAO-2, was the first fully imaging X-ray telescope placed into orbit. After its launch in 1978 it was renamed Einstein to commemorate the centenary of his birth. This breadboard as well as the flight detector were built by American Science and Engineering.
The Smithsonian Astrophysical Observatory transferred it to NASM in 2002.
Transferred from the Smithsonian Astrophysical Observatory, Harvard University.