Scattered light (SL) is present in all spectrographs due to unwanted reflections, non-optimal
optics, unwanted higher orders etc. Not all instruments suffer the same amounts due
to differences in design, but typical values are around a few percent.
In order to fully characterize and monitor the performance of a given instrument it is
necessary to measure the SL as often as possible and preferrably for the full wavelength range.
To accomplish this, an automated procedure must be implemented for all instruments within
Since the CES is the instument most severely affected by SL, it was decided to implement
the monitoring for CES first.
(see the User