I was capturing some spectra from some M-class stars last night. I think I was doing pretty well with focus as I was getting some nice, deep absorptions. However, as you can see in the attached of betelgeuse,
my absorptions are shifted to the left at the red end and shifted to the right at the blue end. This also happened with Mira.
I am using my Evolution 8 + 178MM + SA-100 at 3.65 A/pix
Any idea why this was happening?
Thanks in advance.