Any idea what this is?

[Graham Darke]

On Boxing Day evening I was imaging the Heart and Soul Nebula with an old Zeiss 135mm lens and my L-eXtreme filter. It’s not the best image but something caught my eye in the frame and I’m wondering if anyone knows what this is? Below are the full frame with position of the object marked with the arrow and a close crop. It looks like a circular disk around the semi-regular variable star CQ Cassiopeia. I’ve done a search online of previous images of this region and can’t see this feature on any of them. I’m trying to figure out if it’s real or not? Could be a reflection or halo but seems odd that no other stars have similar such halos. Also the star’s colour index is red so would expect a red halo if that’s what is was. The image consists of 3.5 hours worth of 300s subs at f3.5. Grateful for any views. 
 

Cheers,

Graham

[Mognet]

I had a look at an image I spotted on the Samyung 135 thread here Looks like it's a real thing rather than a lens effect as it appears on that image too, albeit faintly. I suspect it's lost in processing with other images. No idea what it is though

[wimvb]

Probably a planetary nebula.

Couldn't find anything on Aladin or Astrobin, so it could very well be a reflection artefact.

Edited December 29, 2022 by wimvb

[Graham Darke]

3 hours ago, Mognet said:

I had a look at an image I spotted on the Samyung 135 thread here Looks like it's a real thing rather than a lens effect as it appears on that image too, albeit faintly. I suspect it's lost in processing with other images. No idea what it is though

Thanks Mark. That it appears on another image is great, it tells me that it isn’t a processing artefact that I have introduced. The object appears blue green on my image but magenta on this one which may be filter related. I’ve got some local guys here trying to image it in O III.  

[wimvb]

It seems to be a different size in the images in these posts.

[Graham Darke]

It does look very slightly bigger in my image I think compared to the other shot which looks to have been taken almost a year ago. It may also be a slightly different shape. Curious. 

[Graham Darke]

Update on this. A friend of mine took a 15 minute sub tonight through a 3nm OIII filter and it showed a nice clean background with not even a hint of anything else there. Conclusion, therefore, is that this is a reflection/halo from the filter I was using.