Editing ROSAT (section)

=== {{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.