Background Artifacts in R,G,B ASI294MM Bin2 Mode

lambjl1

I am seeing large-scale "ellipse-like loops" (about 3-4 arc-min) in the background of R, G, and B images (see attached images from the blue filter) acquired with the ASI294MM in Bin 2 mode. I'm using Gain=0, Offset=10, Exp=100 sec, T=-5C. I do not see these artifacts in Lum in Bin-1 mode. Any idea what is causing this?

Thanks

Jay

Tech@ZWO

lambjl1
Did you open the dither when imaging?

lambjl1

No. I've never dithered. I doubt that is the cause. I have never seen these artifacts with the ASI1600MM. Nor do I see these artifacts with the Lum filter on the ASI294MM in Bin-1 mode. If not dithering were the cause, I would have expected to have seen this before.

Tech@ZWO

lambjl1 I suspect that is the cause. this noise will be more obvious when you stack more frames or high SNR, and it also lies on the environment, you can open dither to try.