Yes, it could be a reflection of a star off the edge of the prism on the OAG causing it. If the prism height is adjustable, you might want to move it up slightly. Also check to see if the inside of your OAG body or any adapter in the imaging train is shiny, which could cause a reflection. How are you connecting the CCDT67 to the scope? I think you had previously told me that you are using a Baader Clicklock SCT adapter to connect the reducer to the scope baffle nut threads. Check that also for possible reflectivity, but I would think that Baader would use flat anodizing or paint inside the Clicklock body. Also try imaging without the Optolong filter, to see if that is the culprit.
When you say to move the prism up do you mean towards the guide camera or away from it? I am using the Clicklock, but I don't think it is that as it is flat on the inside. What I do with the CCDT67 is have spacers to get from T2 of the OAG to the M48 of the CCDT67 for the proper EdgeHD spacing, then I just adjust that in the Clicklock to get the right spacing for the Edge. I'm still playing around with that though and am having trouble finding a good way to make it perfect (and repeatable). I can see why you switched to just imaging at f/10.
Little off topic: how's going the 247? I am really curious about that sensor.. (Noise,banding,amp glow..)
It is a really great camera especially for an OSC. I have been finding I get better results with it than a mono setup and LRGB filters with the ZWO ASI1600MM-C (though that could just be me). I would probably just sell that mono setup except that I like having the use of the Ha filter for when the moon is out. The 247 has extremely low noise, a bit of amp glow even though QHY says there should be none (though I wonder if to enable their amp glow reduction it has to be done in Sharpcap, which I know has a box to turn on amp glow reduction). Either way it calibrates out fine with flat darks. Here's four hours on M42 from the other night in red zone light pollution (just the Optolong UV/IR cut filter) with QHY247C and my AT106LE scope: https://www.astrobin.com/322192 You can notice a bit of banding if you look on the dust clouds near Running Man, but I probably could get rid of it with the script in PI. I have a few others on there with the camera as well, but none of them have any banding so not really sure if was just something I did with M42 that caused that.
Edited by jtrezzo, 20 November 2017 - 05:17 PM.