That looks interesting
I have not used this before but cannot find a description of exactly what it does on Christian’s website (It is not mentioned in his ISIS change log for example where I normally look). I had assumed it just automated the usual “differential spectroscopy” procedure, using the “response” and “continuum” functions under the profile tab to calculate the response using a reference star at a particular air mass which is then used with the target star spectrum at similar air mass. Does it do something different to this?
EDIT:- rereading your paper, am I correct in saying that the response assistant calculates the response using only the flat and the reference spectrum? ie you do not need to measure the reference star?