Replying to @dokeeffe from his comments on indilib.org/forum/general/7863-the-new-analyze-tab-thanks.html

Derek,

Thanks again for trying out Analyze. I agree that an SQR-type measure is something that should be in Analyze.

SQM itself is possible, but there are complications . For example, I believe the right way to do it is to subtract a dark from the signal,
get the median pixel value, multiply by the inverse of the bandwidth of the optical system, (e.g. if you're using a Blue fliter, or more extreme Ha,
fewer photons reach the sensor than if you're using an L, or a 1-shot camera) then do a little math--have it written down somewhere
This is complicated by the need of the dark and the need to know the filter bandwidth, but certainly possible.

I did provide "Sky Background", the checkbox furthest to the right on the 2nd line, which is the background sky value SEP (Sextractor)
computes when extracting stars, but I see yours isn't populated. I think you need to be using SEP MultiStar guiding to get that value.
I can improve requirements like this after 3.5 when SEP improvements being done by @rlancaste are scheduled for release
You might SEP MultiStar guiding and look at the sky background feature if possible.

Another straight-forward thing I could do is simple add the median pixel value, which is "pretty much the same" as the SQM, except of course
it's linear, not log, has an offset, is affected by filter bandwidth, ... I have gone through the exercise of computing SQM from median pixel values.
Obviously SQM would be more ideal, though.

Adding new features (now that I've filled up the 2 rows) would required a little UI redesign, but I don't think it's too bad. I had planned on organizing
these features into "guiding", "image" and "mount" sections, and SQM and ellipticity would fit in the image section nicely.

What do you think? Would the basic median work for you? Does sky-background look OK as is?

Hy

PS I see you're afflicted with the same "after focus guiding correction" that afflicts me.
I'll definitely look into this further someday, if someone doesn't beat me to it.

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