The famous Veil nebula is not the only large supernova remnant in Cygnus. The Sh2-91 complex is on the other side of the constellation and similar in size, but I don’t think it was even discovered until the 1960s due to how faint it is.
It shares a similar aesthetic to the Veil, same filaments and wisps, but it is extremely faint. I decided to go deep on it and spent most of the past month imaging it with my scope hosted at the Bortle 1 skies at Starfront Observatory in Texas.
The object is very large, this is just a piece of it. I took 600s subs in HA and OIII for over 55 hours over the past monh using a 5” f/7.5 refractor. Even with such a long exposure, each sub just barely showed any nebula. It was extremely faint and really required these dark skies and long integrations. I can see now why it is seldomly imaged. Unlike the Veil, it is much more dominated by OIII, and I’ve found that I always need more integration with OIII compared to HA.
Astrobin has examples of this object in wide field, but fewer detailed studies, and very few with long integrations.
It is in a brilliantly dense Milkyway region there were 13k stars resolved in this image and I had to time them down. But just the RGB stars set I had was gorgeous on its own. Very colorful and lovely. There is a faint HA background in this area that I was just starting to pickup, and I might add to this in the future. But after 55 hours, I was ready to move on to something else.
Thanks for looking!
Astrobin Link for tech details: https://app.astrobin.com/i/eoqhb2