Stellar mode flatfield correction and wavelength solution

[nrsegovia]

Hello, I have been working with the stellar mode and I have noticed a couple of problems. First, it seems that the definition of the interslice region for the blue arm is a bit odd. This leads to problems in the flatfield correction, as can be seen in the following plots:

I believe I have managed to trace back the issue to the offset being used when computing the interslice region. For the red arm, the default value of 2056 works perfect, but the blue arm needs a different offset. Setting 2068 improved the results:

However, I think that (perhaps) changing the definition/defaults for the interslice region in the blue arm would be better, to keep a single offset value.

A more difficult problem that I have not managed to solve is the wavelength solution. I have a source with XSHOOTER spectra that yield an RV of ~-7km/s, but WiFeS observations yield a ~-700km/s RV. I have tested different epochs of this sources with WiFeS, though I have yet to check if the issue is also present in a different source.