› Forums › Spectroscopy › Extended spectra – quick question… › Thanks Robin
1 February 2017 at 9:59 am
#577890
![](https://britastro.org/wp-content/uploads/2020/11/picture-1574-1605195049-80x80.jpg)
Participant
That makes sense, I think I understand now. To paraphrase – process both target and ‘sky’ in the usual (separate) ways, with ‘sky not removed’ ticked in ISIS to produce two spectra using a nearby reference star, then mathematically subtract sky profile from target profile (in ISIS tab 5 “Profile”).
Regards
T