ST-ECF Instrument Science Report

POA/FOS - 2001- 007
POA Investigation of FOS Dark Correction

P. Bristow, A. Alexov, F. Kerber & M. Rosa
November 2001

Abstract
The dark flux correction step of the Faint Object Spectrograph
calibration pipeline was investigated with the joint aims of
applying a more physical model and improving the performance
of the pipeline. After processing with the pre-existing calfos
pipeline, dark calibration data shows a large scatter in count
rates. We were able to reduce this scatter to some extent by
scaling the correction according to the magnetic shell
parameter. However, we were unable to find other
parameterisations, having either an empirical or physical
basis, which would reduce this scatter further. The
distribution of the size and intensity of dark events, epoch
dependency and the form of the diode mask were also
investigated.