Sky Background

[Morten Lerager]

Hi'
After a preprocessing with 20 frames of Pacman I get a Report
I get a table where I can see the sky getting darker as time goes by :

But how is this, to be read. What is the Y axe with a value of 2190 ?
Can I translate it into a Bortle value https://en.wikipedia.org/wiki/Bortle_scale

[merlin66]

Morten,
I'd assume that the minor (0.45%) improvement is due to the improved SNR with the stack.

[Morten Lerager]

Thank's

If I only gain 0.45% SNR then I didn't hat to stack them at all.
And if I fiddle with the filenames it will come out with another table as you see.
It's seems AA has it's one filename sorting. Expecting a numeric value in the file name.

So I still want to know, what is the graph's Y axe ?
And can I translate it, into a Bortle value ?

[Rudi]

"sky background" is the average ADU value of the background in the image.

[Morten Lerager]

Ahh, thank you Rudi.
Then it would not be possible to convert to Bortle I give.
Bortle is for the eye, ADU for the camera, Gain etc.
But the picture background are dark, and ADU 2100 is pretty dark
The curve shows me the sky getting darker as times goes by.
Right until someone hits the light inside or outside the house.
(don't hope it was the wife )