TheSkySearchers

Hello all -
I am getting the following image upon stacking and stretching them. This is from an ASI294MC-cooled. This started happening about six weeks ago - (yeah, I'm just finding time to process them... been a very busy fall season).



I do recall that several months ago (I *really* wish I had put it in my log book) the camera fell off it's table while I was taking darks. I did not see any damage whatsoever - not even a ding. I'm not sure but I thought it was in the summer...long before these "arcs" started showing up. Besides should not (more recent) darks be dealing with background noise?
I'm completely stumped.

Wow, I'm sorry, but I don't have any words for you. I'm just as stumped as you are, and I own the ASI 294MC lPro Camera, and I've never seen anything like this in any of my images.

This usually occurs when images don’t have enough discrete colors or amplitude steps. For instance, if a typical image only had 16 colors, similar gradient steps would be seen in images of the sky or horizon. I can’t answer specifically for your particular camera, but it is probably a setting somewhere that got changed.

Can you make the stacked but unprocessed image available on a shared drive like one drive or drop box and I'll take a look and see if I can work out what's going on. Also provide details of the capture, number duration of images, how stacked, etc.

The Wave Catcher wrote: ↑Wed Dec 27, 2023 1:35 am This usually occurs when images don’t have enough discrete colors or amplitude steps. For instance, if a typical image only had 16 colors, similar gradient steps would be seen in images of the sky or horizon. I can’t answer specifically for your particular camera, but it is probably a setting somewhere that got changed.

That's what I'm thinking too. It looks like an 8bit image from a 14bit original. Somewhere along the line in your processing you have downsampled the image to 8bit.

The Wave Catcher wrote: ↑Wed Dec 27, 2023 1:35 am This usually occurs when images don’t have enough discrete colors or amplitude steps. For instance, if a typical image only had 16 colors, similar gradient steps would be seen in images of the sky or horizon. I can’t answer specifically for your particular camera, but it is probably a setting somewhere that got changed.

OMG! It's solved. I awoke this morning at 2:30AM and could not get back to sleep thinking about this. I got on my computer and went to the directory where the above image was stacked. Deep Sky Stacker (DSS) creates an autosave file every time you stack. I selected one and did a quick process in Star Tools.... vivid colors - no arcs. I tried another image with similar results. I went to the "final" directory - where I save the stacked image as a .FIT and reprocessed it... arcs! OK, so WTF - it had to be in DSS. I pulled up an autosave file of NGC1333 and went to save picture. Now I started doing this under a previous version (updated in September) because DSS would save the file as a TIFF... and I need a FIT to work in Star Tools. When the file save requester popped up I noticed that there were several versions of Fits to choose from.... I never paid any attention to that because in the previous version of DSS I just typed in the name.FITS and everything was fine. The new DSS defaulted to 16 bit NOT 32 bit... and voila' that was the problem. So It wasn't the camera (YAY!) it was a minor change in DSS that tripped me up. I hope this lesson learned is helpful to someone in the future. I now have several months of image to post process (It's not that many - maybe 15 or so). But I am soooo happy. Thank you Wave Catcher for getting me to look in a direction I never even thought of. And to the others who responded after Wave - I just saw your posts and you also had the right idea. I LOVE this community

Great, lets see it then

Ok, I'll resize it and post the Rosette Nebula which I just processed from November.... but I do 90% of my work on Linux and the image is on the windows side of things. And lately I've been having arguments with the windows boot loader which insists on being THE boot loader, so I've had to separate my dual boot system. I'll post a pic tomorrow as I'm running out of time for today.