Hi.
It’s interesting you mention that paper in particular… I’ve used the spectra presented in that paper as a calibration starting point for many of my own!
I think elsewhere in my forum posts I actually show a comparison between my own set up, at the time, and the VLT one.
Whilst mine was a lucky capture to be sure, the VLT one, given the field of view and size of slit was freaky lucky!
Bill.