SNR G65.3+57 is a huge supernova remnant in Cygnus, not so far away from the much more famous Veil Nebula. It was only discovered in 1977, by Gull, Kirshner and Parker. Their paper here is an interesting read, and includes the OIII plates they used to identify it. The overall shape of the supernova remnant is mostly defined by the OIII - earlier Ha images hadn't revealed it,  although Sidney van den Bergh had speculated that the identified Ha areas might be part of a SNR (Stewart Sharpless had already named the Ha rich parts of the SNR - Sharpless 2-91, 2-94 and 2-96 are all here).

SNR G65.3+57 is slightly bigger in angular measurement than the Veil (I guess about 5x4 degrees) , and much bigger in actuality (c 230 LY to c 100 LY), and older - maybe up to 30,000 years or more vs 10,000 years. Recent estimates put the distance at around 5,000 LY, to the Veil's c 2,100 LY.  I have seen this object called the "Little Veil" - but I'm afraid, based on this information, I don't like that name. Perhaps "Big Veil" would be better!

Anyway, the end result of all this is that unlike the Veil, this SNR is very faint, and to make things trickier it also sits in an incredibly rich star field. I had a go at this in broadband, but perhaps not surprisingly only got some faint Ha with that attempt, so used that data purely for the stars in this image. The main image was captured using my NBZ filter, which has done a pretty good job I think for OSC and dual narrowband. This is a 2 panel mosaic. I could only get the whole SNR into a 6 panel mosaic, as it just overflowed the 2 panels in each direction, but I quickly decided that with my weather, this would be an endeavour that would take at least into next year, so decided to frame the image in way that perhaps accentuates its size, bulging out in each direction!

I should add - if you want to see the full extent of this object, I recommend the wonderfully detailed image by buckeyestargazer that you will find on his website (6 panel mosaic of 176 hours!)