The ultraviolet calibration system for the UK XUV telescope to be flown on the ROSAT satellite

An imaging XUV (6.2-31.0 nm) telescope (the wide-field camera (WFC)) is to be flow on the German X-ray astronomy satellite ROSAT. The calibration system uses a series of fused silica lenses to project the magnified image of a rectangular array of 20 mu m diameter illuminated spots on to the XUV detector (a microchannel plate), so that any misalignment of the XUV mirror system or distortion in the image plane can be readily recognised.