Help Requested Identifying/Eliminating this Artifact

[admin]

Hi Gary,

thanks for sharing those files - my first run through gave me a clean image stacking the raw frames with no artifacts in it, so I started setting up the same image processing options as you had recorded in the capturesettings.txt file. Everything seems OK except for the 'Low Frequency Wave (Experimental)' background subtraction mode, which does *horrible* things to the stacked images. I didn't get the same octagonal effect as you, instead weird shadows and negative effects in the stack, but it certainly seems worth turning that option off (or trying one of the other background subtraction modes - they all seemed fine) to see if the weird octagons disappear.

Here's what I get from stacking the raw frames with no processing... A lovely image!

Screenshot 2024-12-27 174545.jpg (190.62 KiB) Viewed 2267 times

cheers,

Robin

[GaryS]

Robin thank you !!!

I was pleased that none of the individual fits images, or fits stacks, showed the artifact since most of my time is spent working with variable stars, eclipsing binaries and exoplanet imaging. But, when I need a break for some fun and relaxed observing, I open up Sharpcap and go find something beautiful ( like the Bubble Nebula) to watch and sketch as the images stack before me.

I had forgotten I’d ever selected the experimental background option and failed to even look though my settings to see if something was off. Thanks very much for finding the problem. Have a terrific 2025.
Gary