Astron. Astrophys. Suppl. Ser.
Volume 120, Number 1, November II 1996
|Page(s)||187 - 193|
|Published online||15 November 1996|
The energy-dependent temporal variation of the ROSAT PSPC gain
Max-Plank-Inst. für extraterrestrische Physik, Germany e-mail: email@example.com
2 Astrophysikalisches Institut Potsdam, Germany e-mail: firstname.lastname@example.org
3 USRA/Goddard Space Flight Center e-mail: email@example.com
Send offprint request to: M.A. Prieto
Accepted: 24 February 1996
The existence of systematic spectral-fit 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 per year is measured at 1 keV. A quantitative description of the PSPC gain-time 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.
Key words: instrumentation: detectors / methods: data analysis / methods: observational / X-rays: general / space vehicles
© European Southern Observatory (ESO), 1996