Hi!
Thanks, Robin, that is a very good idea.
I’ve been experimenting as much as I can, trying to make sense of this. Last night, I captured spectra of 4 stars w Miles spectra – I found them via ReferenceStarFinder and checked in the Paolo Berardi excel-file and in VSX. It looks like it is a bit hard to find a good ref-star close to SS Cyg – or …? 🙂 Stars are:
HD169027: this was the only one of the 4 that was NOT in VSX, not identified as variable. It is in Dra, and a little bit of distance from SS Cyg – however, at similar altitude last night when I captured them.
HD198478: Blue giant, slightly variable
HD199878: similar, blue giant, slightly variable
HD207330: spectroscopic binary.
The last three are close in Cygnus.
I then tried producing response profiles from all and cross-process them. I did the whole process both with bin 1×1 (raw) files and no flat, and with the CMED process, so they are bin 2×2 and there is a flat involved. Interestingly, these two ways produce somewhat different results.
Attached are two comparisons betwen the 4 reference profiles, one with profiles produced in bin1x1-noflat-mode, the other in bin2x2-withflat-mode. Interestingly, there is significantly more difference between them in the bin2x2-withflat-mode! Moreover, in both, HD169027 stands out. Possibly the distance leads to different profile….?
Processing the stars: I can get good alignment between the two giants – see attached screenshot. Again, clearly better in bin1x1-noflat mode.
So, how can I make sense of this? Is it my flat with very weak signal in the blue (I use a halogen lamp) that plays games with me? Am I doing something wrong? I must admit that this is quite frustrating…. Any ideas very welcome. And I’d be happy to share any of these files….
Magnus
