what causes this "noise"

[PaulR1]

Couple of images from M78 I did on the 24th feb which was  quite a moonlit night .

Just wondering what causes all the red noise in the image.

40 images @ 4 min, 800ISO stacked , using CLS LP filter on canon 450D. Not too worried abut the processing of this , I will mess about with it just interested in what causes the red noise .

image 1

Just ABE in PI

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Same image using a preview

[wxsatuser]

Passing thin high cloud, was there any about?

[vlaiv]

1 hour ago, PaulR1 said:

which was  quite a moonlit night

I think there is your explanation. Together with CLS filter.

It's just a regular type of noise, in this case dominant in red part of spectrum. If you look closely, you will see that it's not all red, there is a bit of blue as well (probably blue black point was pushed down in comparison to red).

Green is lacking because CLS cuts of part of spectrum where green is sensitive (middle part of spectrum).

If you split your subs into R, G and B components and process each as mono, you will find that each is noisy.

[PaulR1]

thanks guys appreciate the input

been having lots of fun with PI to get ride of this. Seems to be working out ok .

Part of the Markarian's chain from last night below