This SNR is just north of Albireo in Cygnus and comprises Sharpless 91, 94 and parts of 96, but also other parts that bear no further designations. Its size and appearance is similar to that of the Veil, but it is farther away (2500 instead of 1500 LYs), considerably older (estimated 30000 instead of 7500 years) and hence much dimmer.
This SNR was discovered as a SNR by Kirshner, Gull, and Parker in the 70ies. The first "good" OIII image is by Fotis Mavromatakis from Shinakas Observatory in Crete from 2002.
SH91_c.jpg
image: http://arxiv.org/abs/astro-ph/0204079v1
Here is a finder chart as an overlay with the OIII image with the main filaments being numbered
SH91_findersmall.jpg
larger chart: http://www.reinervogel.net/artikel/I..._finderbig.jpg
The Sharpless 91 part constitutes, of course, the brightest part of the SNR. This part comprises, however, much more than only the tip of the main filament south of Phy Cygni. Surprisingly, the filaments in the unnamed NE segment are not considerably fainter and appeared to me easier than that of Sharpless 94 and of course that of Sharpless 96.
Here are my observing notes of the single filaments (still to be continued):
Sharpless 91 filaments
The brightest part of the SNR is filament 01, which is directly SE of Phi Cygni and which appears as a very faint narrow segment. Coming from NE, it is passing through mag 8.2 star HD185735 about 15' south of Phi Cygni. The filament extends beyond this star, becoming fainter and more diffuse. After having passed behind 9 Cygni, it can be picked up again as a better defined filament 02, and even the bifurcation towards 2 Cygni to the west can be perceived. Parallel and NW of filament 01 is extremely faint filament 03, which I have not observed yet. Filament 04 is even a bit further NW and appears fainter and narrower than filament 01. The observation can be verified by its precise location relative to a mag 7 and two mag 8 stars aligned to it. In the very west is filament 05, an extension of filament 02, which I have not observed yet.
Sharpless 94 filaments
The filaments of Sharpless 94 are considerably fainter than those of Sharpless 91. After many unsuccessful attempts, I was able to observe the southern end of filament 11 as an extremely faint N/S oriented elongated glow. Towards north, the filament merges with the background and I could not trace it up to the two conspicuous mag 10 stars.
The southern E/W oriented filament 12 could not be observed up to now.
Sharpless 96 filaments
Sharpless 96 comprises besides the long SNR filament also HII regions, which are possibly not associated directly with the SNR. The catalog position of Sh2-96 is therefore not coinciding precisely with the position of the long SNR filament.
In this area, filament 21 was several times suspected as an extremely faint and narrow filament.
NE filaments
This series of filaments does not bear any catalog designation. Of these filaments, filament 33 appeared as the most distinct. It trails between the two mag 7 and mag 8 stars HD185602 and 185660 and can best be viewed about 15' west of this pair as an extremely faint structured glow slightly above the background. Further towards E, filament 32 becomes somewhat fainter and was visible as an extremely faint patch trailing north of another fainter pair of stars. Filament 31, which appears relatively bright on the OIII images, was similarly bright. Its very narrow angled southern end was about similarly difficult as the broader part of it that trails towards NW. At the other end of this part of the SNR is filament 34, of which the brightest part appeared as an extremely faint elongated patch.
Central filament
Filament 41 is in the central part of the SNR and is an extension of filament 04, turning towards west. Not yet observed.
More information, links to images and to papers is on my website
http://www.reinervogel.net/artikel/Sh91_SNR_e.html
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