North America Nebula Region

[Astrodoc]

I continue to be impressed by both the Optolong L-eNhance filter and the QHY367C one-shot colour camera for this type of target.
http://astrodoc.ca/ngc7000-2019/

Clear skies,
Ron Brecher

[mmnb]

Very nice!
Do you mind elaborating on reasoning behind to the two background reduction steps? I always only do 'subtract', now I've only just  heard of  Carlos' method (which I can't actually find now) where he does some sort of linearization of the bg model and then only subtraction.

[Astrodoc]

Division to remove multiplicative gradient (imperfect correction of flats, for example). Subtraction to remove additive gradients. I don't always use both; it depends on the image. Subtraction on its own can give a very nice result most of the time.

Clear skies,
Ron