Design, construction, and performance of the ROSAT highresolution x-ray mirror assembly

A grazing incidence telescope has been developed for the x-ray astronomy satellite ROSAT including a verification model and a flight model. The telescope consists of a fourfold nested Wolter type I mirror assembly of 84-cm front aperture and 240-cm focal length. The verification model has been built and fully assembled to a telescope. Full aperture x-ray measurements performed in our 130-m long-beam facility are pesented and successfully compared with model predictions based on mirror metrology data. An energy independent angular resolution of 4-sec of arc half-energy width for the encircled point spread function and a mirror surface microroughness of