Soft X-ray in-flight calibration of the ROSAT PSPC

TL;DR

This paper details the in-flight calibration of the ROSAT PSPC instrument using known soft X-ray sources, improving accuracy and correcting response matrices to reduce systematic errors.

Contribution

It provides a new, precise calibration of the ROSAT PSPC for energies below 0.28 keV, correcting previous miscalibration issues.

Findings

Calibration accuracy better than 5% for E < 0.28 keV

Response matrix corrections reduce systematic residuals

Refutes earlier reports of major miscalibration

Abstract

We present an in-flight calibration of the ROSAT PSPC using the incident spectra of the hot white dwarf HZ43 and the polar AM Her. We derive an absolute flux calibration of the PSPC using the accurately known soft X-ray spectrum of HZ43. Corrections to the PSPC response matrix are derived from a comparison of predicted and observed PSPC spectra of HZ43, supplemented by results for AM Her. The calibration of the PSPC for photon energies E < 0.28 keV is found to be accurate to better than 5% refuting earlier reports of a major miscalibration. Our corrections to the detector response matrices remove systematic residuals in the pulse height spectra of soft sources.