Hi all,
I’ve been following these posts with some interest, having performed similar tests over the past couple of years while coming to terms with with the ‘black art’ of instrument response correction with both the Alpy and Lhires spectrographs. Most recently (during a spate of bad weather) I’ve been playing around with the response assistant in ISIS. I don’t think the response assistant was developed as a serious replacement for the more rigorous method (as far as I can tell, it can’t correct for atmospheric attenuation) but I’ve been achieving some interesting and remarkably good results despite that, which I’m still trying to get to the bottom of.
The attached profile is a spectrum of HD4150, corrected using the response assistant (blue), with the Miles standard HD31295 and a high quality master flat as the input. The comparison with the Miles standard (red) shows excellent correlation.
A short draft report on the process and some early findings can be found here if of any interest:
http://jazzistentialism.com/blog/wp-content/uploads/2016/11/correcting-instrument-response.pdf
Best wishes,
Paul