Fri, 01/31/2020 - 16:15
Finally I got an SA200 and as soon as the sky clears (hopefully few days) I am planning to start taking some spectra.
I still have some doubts about the proper techinque in terms of calibration and stacking.
After the dark subtraction can I stack images and then use a software such as R SPEC to do the wavelength calibration? Or shall I first wavelength calibrate every single frame and then stack the wavelength calibrated frames? If the latter is the way to go, how can I save the calibrated individual files to be stacked? I have to admit that I am a bit puzzled..
Cheers
Gianluca
You can do either (ISIS for example digitises each exposure individually and combines them to produce the final calibrated spectrum but that is all done automatically in the background so is not obvious to the user)
Normally with Star Analyser spectra though you combine the exposures first, aligning and stacking them using your favourite image processing program (just as you would with astro-imaging) and then pass the final image back to RSpec, Vspec or some other program to digitise, wavelength and flux calibrate the spectrum.
(Note the real time feature in RSpec is useful to fine tune the focus and exposure before capturing the series of exposures you are going to process)
Cheers
Robin
You dont need to worry too much about dark subtracting, aligning and stacking to start with though. You can learn on bright targets by working with the spectrum RSpec produces live to begin with with, learning how to remove the sky background, digitise the spectrum and wavelength and flux calibrate it using a reference star.