The energydependent temporal variation of the ROSAT PSPC gain.
Abstract
The existence of systematic spectralfit residuals in ROSAT PSPC spectra, and their dependence on time, is by now a well established fact. This paper describes how those residuals may be related to second order variations of the gain of the PSPC as a function of energy and time. As a result, the energy scale used for the interpretation of PSPC spectra can be incorrect producing significant systematic effects, in particular at energies where the effective area of the instrument changes rapidly. A monotonic gain decay of ~1% per year is measured at 1 keV. A quantitative description of the PSPC gaintime variation as a function of energy is provided. The functional dependence of this variation is found to be well represented by a second order polynomial.
 Publication:

Astronomy and Astrophysics Supplement Series
 Pub Date:
 November 1996
 Bibcode:
 1996A&AS..120..187P
 Keywords:

 INSTRUMENTATION: DETECTORS;
 METHODS: DATA ANALYSIS;
 METHODS: OBSERVATIONAL;
 XRAYS: GENERAL;
 SPACE VEHICLES