XUV wide field camera for ROSAT

The ROSAT project is an international collaboration between the Federal Republic of Germany, the United Kingdom, and the United States. The satellite, due to be launched in June 1990, carries a payload of two coaligned imaging telescopes: the German X-Ray Telescope (XRT), which operates in the soft x-ray band (0.1 to 2 keV or 6 to 100 A), and the UK Wide Field Camera (WFC), which operates in the XUV band (0.02 to 0.2 keV or 60 to 600 A). ROSAT will perform two main tasks in its anticipated two to four year lifetime: a six-month all-sky survey in the soft x ray and XUV bands followed by a program of pointed observations for detailed studies of thousands of individual targets. In this paper we review the design and performance of the WFC. The instrument is a grazing incidence telescope comprising a set of three nested, Wolter-Schwarzschild Type I, gold-coated aluminum mirrors with a microchannel plate detector at their common focus. Thin plastic and metal film filters define the wavelength passbands.