FIES skew readout mode
This is the documentation for the skew readout mode of the FIES CCD.
The chip is readout using coarse on-chip binning, where the binning
pattern follows the curved echelle orders. The binning reduces the
effective spectral resolution. This readout mode was developed by
There are two advantages when using this mode:
quick readout (e.g. for high time resolution)
low noise (e.g. for observing faint objects)
Skew readout mode uses pre-defined echelle order masks to sum over
orders and along dispersion direction. This mask needs to be created
for each object, since the spectrograph is currently not yet in a
stable environment, and slewing the telescope makes the echellogram
jump around on the CCD.