Hi Jeff,

That's a very interesting observation!  The object you mention is associated with a red star seen in several other images in the archive, e.g. January 2022,  December 2021 and September 2021.  The ring is very obvious in your image but not in the others. Well worth investigating...maybe a variable nebula!? Could be an image artefact but unlikely as it is the only one in the field and it is associated with an 'unusual' star.

Clearly there has been a lot of different image processing applied to all these images and the resulting colours are quite different.  Probably needs several more images over the coming months with the same equipment and processing to see what is going on. 

Very interesting...and well worth going through the archive in more detail to look for it in the past.  This field receives a lot of attention so there must be very good, frequent coverage over many years.

Mike.

Nik Szymanek's image from July 2020 doesn't show anything associated with that star!

I have a red-sensitive widefield image of this region taken on Aug 20 that shows nothing unusual. I've put a comparison here. 

Hi Jeff,

Yes, sadly it looks like an imaging artefact rather than anything more interesting.  Bad luck it appeared almost centred on a star!  My image from this morning confirms what Nick is (not) seeing.

Might be worth checking some of your other deep sky images to see if it appears anywhere else?

Mike.

Thanks for all the feedback. I have spent this morning checking the images and various databases, as you say there is no record of an object.

The original images show some faint traces in the region, but it only really shows as a ring after stacking. Darks, flats and flat-darks show nothing. I can't see anything obvious in other images either. I have separated out the Ha and OIII from the original colour and the ring is very obvious on both. It's patchy as well rather than even.

Oh well, probably an artefact after all!

Jeff

In case anyone is still interested, I've found (on the web) that the Optolong L-eXtreme filter that I'm using is prone to haloes. I did find another halo around a fairly bright star in the full image, so I guess that's the problem.

Thanks again for everyone's response on this, you learn quicker from other's experience.

Jeff