The ROSAT X-Ray Mirror Assembly
The X-ray Mirror Assembly (XMA) with its 2.40 m focal-length mirror assembly consists of 4 nested Wolter-I mirrors. The focal plane instrumentation consists of a carousel on which there are 2 Position Sensitive Proportional Counters (PSPCs), each with a filter wheel carrying a boron filter, and a High Resolution Imager (HRI).
The XMA consists of 4 nested grazing incidence Wolter-I mirrors with a maximum aperture of 83.5 cm and a focal length of 240 cm. All of the 8 mirror shells (4 paraboloid/hyperboloid pairs) are constructed of zerodur, a glass ceramic with an almost negligible thermal coefficient, these are coated with a thin layer of gold to enhance the X-ray reflectivity. Typical grazing angles are between 1 and 2 degrees, depending upon the sub-shell considered.
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