This book is the result of a working group sponsored by ISSI in Bern,
which was initially created to study possible ways to calibrate a Far
Ultraviolet (FUV) instrument after launch. In most cases, ultraviolet
instruments are well calibrated on the ground, but unfortunately, optics
and detectors in the FUV are very sensitive to contaminants and it is
very challenging to prevent contamination before and during the test and
launch sequences of a space mission. Therefore, ground calibrations need
to be confirmed after launch and it is necessary to keep track of the
temporal evolution of the sensitivity of the instrument during the
mission.
The studies presented here cover various fields of FUV spectroscopy,
including a catalog of stellar spectra, datasets of Moon Irradiance,
observations of comets and measurements of the interplanetary
background. Detailed modelling of the interplanetary background is
presented as well. This work also includes comparisons of older datasets
with current ones. This raises the question of the consistency of the
existing datasets. Previous experiments have been calibrated
independently and comparison of the datasets may lead to
inconsistencies. The authors have tried to check that possibility in the
datasets and when relevant suggest a correction factor for the
corresponding data.