Telescope Reviews: SNR G065.3+05.7: Sh2-91, Sh2-94, and Sh2-96

Among all the bright and flashy DSOs in Cygnus, the supernova remnant SNR G065.3+05.7 largely gets ignored, partly for its flashy neighbors, but mostly for its faintness. This ancient, faint, and very large supernova remnant has three segments which were bright enough to make it into the Sharpless catalog as Sh2-91, Sh2-94, and Sh2-96; however, none of these segments made it into either Uranometria or Megastar.

I was first alerted to the existence of this object (most specifically, the Sh2-91 filament of SNR G065.3+05.7) on the Cloudynights forums by Steve Gottileb (thanks Steve!) in October 2007, shortly thereafter observing Sh2-91 under the dark skies of south Alabama. I found Sh2-91 *fairly* easy to see with an OIII filter in my 18” Obsession.

Objects like Sh2-91, Sh2-119, Sh2-216, Sh2-308- all very observable nebulae that are completely left out of Megastar and Uranometria- finally convinced me to go through and find images of all Sharpless nebulae, trying to find more hidden “gems”. In my search, I found out about the Sh2-94 and Sh2-96 segments of SNR G065.3+05.7, and first searched for those segments visually in June 2008 from the dark skies of the Davis Mountains in West Texas with my 25” dob. I was only able to pick up vague hints of Sh2-94, and no sign of Sh2-96.

This year in my observing trip to the Davis Mountains, I resolved to give SNR G065.3+05.7 another try. My last night of observing was May 31/June 1, and as the moon set in the early morning hours, the skies darkened beautifully. An incredibly detailed Milky Way sprawled overhead as I turned my 25” dob to the southern Cygnus abode of SNR G065.3+05.7.

I started my survey of SNR G065.3+05.7 by reobserving the Sh2-91 segments. Beginning just southeast of phi Cygni, I was able to pick up a fairly easy, very thin streak running roughly east-west using a 27mm Panoptic (100X) and OIII filter. This streak ran about 20’ in length, just north of the stars SAO 87517 and SAO 87498, before dissolving into invisibility just to the northwest of SAO 87498. This segment was brightest on the eastern end, and slowly faded from view towards the western end. While on the eastern end, this streak was clearly nebulous, on the western end, where it dissolved into invisibility, it almost looked as if the stars were somehow linked together. For lack of knowing a better word, I will call this visual impression of linked stars “star chains” as per the precedence set by a few other observing reports of similar objects I have read. It’s hard to describe, but basically, the visual impression of “star chains” happens when a very faint, filamentry nebula is located in a rich star field. Does anyone know of a better term for this?

A degree to the west, I was able to see another segment Sh2-91. Just to northeast of 9 Cygni, I could see the star chains beginning again, and the star chains turned into full nebulosity beginning just to the north of 9 Cygni. This streak started out thick, but quickly tapered down to a very thin, and fairly bright filament that terminated just short of the star SAO 87308. Along the way, a “star chain” broke off the north side of the streak, also terminating just short of SAO 87308, giving the western end of the streak a forked appearance.

The exact locations where I saw these streaks is shown in the chart below. This chart was created using Megastar 5, with the nebula drawn in using MS Paint. Solid lines represent areas clearly seen as nebulous, while dotted lines indicate star chains. Also, a great image of Sh2-91 can be seen at the following link:
http://deanrowe.net/astro/image.jsp?panel=images/sh2_91&image=2
Nice image Dean!

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John T.
Austin, TX
25" f/4.2 Dob
18" Obsession #701
4" Stellar Vue Achromat
8X56 Binos

Edited by tatarjj (06/03/09 01:50 AM)