Last Saturday night (9/19) about a dozen folks including several TAC participants met for a night of deep sky observing at the Fiddletown observatory in the foothills east of Plymouth. I spent the evening tracking down several Abell planetaries, the Egg Nebula (appeared like a bloated double star) and some faint galaxies in Delphinus - but mostly enjoying the company and sharing views with my 16 year-old daughter who was tracking down Messiers with her 10" f/5.6.
At one point, Ray Cash, who was poking around in the M52 region, called me over to take a look at a mystery object he ran into which apparently was not plotted on the Uranometria. Ray posted his comments on s.a.a. and I checked through my observing notes when I returned home on Sunday afternoon I'd also run across this object several years back.
Here is Ray's original posting:
While looking at, or trying to look at some pretty faint nebulae last night (9/19-20/98)in the Cass-Cepheus region I seemed to stumble upon a pretty damn bright nebula that wasn't charted in either Uranometria or The Sky...
M52 is a logical starting point for hopping about half a degree west to the Bubble Nebula (NGC 7635 in Cassiopeia). I wanted to look at it again, since giving some helpful hints to someone here on AOL who was having difficulty finding it in his 10" (I was using a 17.5 w/OIII, BTW). If you've ever spotted the Bubble, you might have been disappointed (we always expect these "named" objects to be showpiece objects, don't we?)... Two distinctive 7-8th mag stars, the eastern most, and dimmest of the two surrounded by faint nebulousity. Now: sweeping just over another half a degree west a bright N/S elongated nebula popped into view--it was at least twice as big and bright as the wimpy Bubble! There was nothing charted on Uranometria at this position; Mark Wagner's copy of The Sky had nothing plotted, either. Even more surpisingly, deep-sky master, Steve Gottlieb, confirmed my sighting and did not recognize it!
Well, when I got home this afternoon, I booted MegaStar up: Sh2-159 *is* charted on MegaStar about half a degree west of the Bubble Nebula (NGC 7635 in Cassiopeia, where we were looking), though the stats say it is only 7' in size (the wimpy Bubble is 16'X6' by comparison, according to MegaStar). No mags given. I would say that the nebula we were looking at was about 30', elongated approximately N/S, and about 11th? mag using an OIII coupled to a 26mm Plossl and 17.5 f/4.5 scope (77x; 39' FOV).
Were we looking at Sh2-159, and the stats are just all wrong? Anybody have any notes on this object?
BTW... While in the vicinity, I went looking for The Cave Nebula, Sh2-155, one of the 110 so called "Caldwell Catalog" objects that Sir Patrick Moore decided to (try to) immortalize himself with, and S&T market boxer shorts with... I found the field, and saw nothing; save some possible dark nebula, since the stars seemed a little extinguished compared to other stars in the region. Hardly what _I_ would include as one of my favorite 110 objects beyond the Messier List! In fact, as Jim Shields said as he left the "non-view" in my eyepiece, "It proves that Moore's list is bogus!" I concur.
Ray
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As this object was so obvious in his scope, I was also amazed that it was unplotted on the Uranometria 2000. But when I arrived home I discovered thatI had made an observation of Ray's mystery object to the southwest of the Bubble with my 17.5" back in November of '91, and I had completely forgotten about this huge HII region. The correct designation for the object is Sharpless 2-157, although this region contains other Sharpless and NGC nebulosities. As Ray discovered, this is a fascinating region to explore, particularly scanning at low power with an OIII filter in a large scope.
Here are my observing notes for the main elongated nebulosity ---
At 100x (20mm Nagler) using an OIII filter, Sh2-157 appeared moderately bright, very large, elongated ~2:1 N-S, ~25'x10'. The brightest region is also the widest and shows subtle structure and brightness variations. The nebulosity appears slightly fainter as it extends in a lane to the NNE with a smaller extension to the S.
In addition, the compact open cluster Mrk 50 = Basel 3 is nestled along the W edge and consists of about 15 stars mag 10-15 including 11 stars in a striking semicircle open on the east side. This is a very tight and compact cluster!
Sh2-157 was also catalogued by Beverly Lynds in the LBN catalogue (Lynds Bright Nebula) as several separate entries - LBN 533, 536, 537, 540 and 544. LBN 537 is a compact knot surrounding a mag 10 star. In the 17.5" it appeared faint, fairly small, round, 1.5' diameter. This is an unusual object as it responds best with an H-Beta filter (only a handful of objects share this characteristic) with a weaker response to UHC filter and nearly disappearing using an OIII filter.
By the way, Ray has put together some DSS images of the vicinity and a couple of the replies posted on s.a.a. at http://members.aol.com/anonglxy/mystery.htm