Editing ROSAT (section)

== Instruments ==

=== {{anchor|XRT}} X-ray Telescope (XRT) ===
The main assembly was a German-built imaging X-ray Telescope (XRT) with three focal plane instruments: two German Position Sensitive Proportional Counters (PSPC) and the US-supplied High Resolution Imager (HRI). The X-ray mirror assembly was a grazing incidence four-fold nested [[Wolter telescope|Wolter I telescope]]  with an {{Convert|84|cm|in|0|abbr=on|adj=on}} diameter aperture and {{Convert|240|cm|in|0|abbr=on|adj=on}} focal length. The angular resolution was less than 5&nbsp;arcsec at half energy width. The XRT assembly was sensitive to X-rays between 0.1 and 2&nbsp;keV.<ref name="NASA, ROSAT" />

=== {{anchor|PSPC}} Position Sensitive Proportional Counters ''(two)'' (PSPC) ===
{{Expand section|date=September 2011}}

There are two Position Sensitive Proportional Counters (PSPC), PSPC-B and PSPC-C, mounted on a carousel within the focal plane turret of ROSAT. PSPC-C was intended to be the primary detector for the mission and was used for the bulk of the All-Sky Survey until it was destroyed during the AMCS glitch on 25 January 1991. After the glitch, PSPC-B was used for all further observations. Two more PSPCs(PSPC-A and PSPC-D) were mounted on ROSAT for ground calibration.<ref>{{Cite web |date=June 22, 2001 |title=The ROSAT PSPC |url=https://heasarc.gsfc.nasa.gov/docs/rosat/pspc.html}}</ref>

Each PSPC is a thin-window gas counter. Each incoming X-ray photon produces an electron cloud whose position and charge are detected using two wire grids. The photon position is determined with an accuracy of about 120 micrometers. The electron cloud's charge corresponds to the photon energy,<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=1990-049A-02|title=Position Sensitive Proportional Counter}}</ref> with a nominal spectral bandpass 0.1-2.4 keV.

=== {{anchor|HRI}} High Resolution Imager (HRI) ===
{{Expand section|date=September 2011}}
The US-supplied High Resolution Imager used a crossed grid detector with a position accuracy to 25 micrometers.<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=1990-049A-01|title=High Resolution Imager (HRI)}}</ref> The instrument was damaged by solar exposure on 20 September 1998.

=== {{anchor|WFC}} Wide Field Camera (WFC) ===
{{Expand section|date=September 2011}}
The Wide Field Camera (WFC) was a UK-supplied extreme ultraviolet (XUV) telescope co-aligned with the XRT and covered the wave band between 300 and 60 [[angstrom]]s (0.042 to 0.21&nbsp;keV).<ref name="NASA, ROSAT" />