ISO's Short Wavelength Spectrometer - Ultimate sensitivity. Reducing the effects of cosmic weather

Abstract

Compared to the pre-launch measurements, the in-orbit noise levels of the Short Wavelength Spectrometer (SWS) detectors show a significant increase, considerably lowering the overall sensitivity. Cosmic ray impacts on the detectors and/or on the instrument electronics play an important role in the noise levels and consequently many observations of faint sources are affected by this increased noise. However, by taking advantage of the high read-out frequency of 24 Hz and the redundancies provided by the observing strategy, it is possible to significantly improve the quality of the data. Here, we present the concept of self-calibration and additional algorithms, which are successfully applied to recover the weak signals of molecular hydrogen lines undetectable in a standard data reduction.