I spent the prior few days pouring over weather and smoke forecasts to see where the best place to go out would be. The southern sites were going to be under poor transparency from Arizona monsoon moisture in the upper atmopshere. Shot Rock was a possibility but Saturday morning a fire near Yosemite flared up putting a lot of smoke over that area. That left Lake Sonoma, and fortunately there was another group going. Steve, Bob, Dennis, Jim, two Dans, and a few others arrived after I did to set-up. The night was clear but there were still transparency issues, and the best SQML reading I heard of was 21.3. After around 1am it started to dew up a little, and SQML was 21.1. I observed until 4:30am (far longer than I planned) and slept for an hour in my car before packing up in the dawn.
I continued looking for Sharpless objects and Steve gave me a four objects to go after. Apparently he had attempted observations in the past but they were marginal or unsuccessful. The first couple were in the southern sky, so I observed those first otherwise they'd be in the Santa Rosa light dome. I made most of my observations to the north, in Cygnus and Cepheus, where the sky is somewhat darker, and late at night in the west, where it overlooks the Pacific and is the darkest.
Sh2-46: 18 06 10.6 -14 09 31, 25' diameter, 4-inch and Ha. The nebula is round and is divided into four pie slices with two wide dark lanes crossing it, the darker lane running NE-SW, with a bright 7th magnitude star in the SW portion of the dark lane. The nebula is brightest from the lines of division and fades to diffuse edges to the sides, but there is a brighter elongated section along the eastern side. Very faint streamers extending beyond the main nebula to the NW and SE. Vogel notes it is 2000pc distant, 14.5pc in size, and "This nebula is located well above the galactic plane. The potential runaway O-star HD 165319 [the bright star mentioned in my observation ] lies within or behind this nebula, which is nearest to the OB association Sagittarius OB6. Polycyclic aromatic hydrocarbons (PAHs) have been detected in this HII region."
Sh2-64: 18 31 35.0 -01 54 47, 25' diameter, 8-inch Ha. Very faint, patchy nebula with a bright ragged patch near a small cluster of stars. Vogel notes 200pc distant, 2.9pc in size, and "This is the W40 star formation region, also called LBN 90, and is ionised by the three B1V stars W 40 OS 1a, W 40 OS 2a and W 40 OS 3a. It is obscured by the dust clouds called the Rift, which are located between W40 and our solar system."
Sh2-88: 19 45 58.4 +25 20 38, 25' diameter, 4- and 8-inch Ha. Fairly large bean shaped nebula with two brighter knots in the northern end with fainter wisps trailing south. B1 and B2 are easily seen as smudges of nebulosity around their respective stars. With the 4-inch I noticed a faint stream of nebulosity trailing from Sh2-88 in a curved arc (outer bend pointed west) south to the large and bright oval NGC 6820 (with open cluster NGC 6823 at its eastern edge, and the large, loose & poor open cluster Ro 2 in the nebulous stream. Vogel lists Sh2-88 at 2000pc, around the same distance as NGC 6820/23 -- and stars in both are part of the Vul OB1 association, so it's reasonable to think the two nebula are connected by this stream. This Aladin screen shop (with the blue lines to show the faint nebula stream) hopefully shows it:
DWB 111/118 (Propeller Nebula) & IC1318A: Dramatic, bright and easy in both 4- and 8-inch, DWB 118 is the northern curve and 111 is the lower, separated by a dark lane, these are two bright and bulky streams in a field full of streaks and wisps of nebula, including one along side DWB 111, and another bright streak below the propeller, which leads the eye to a stream of faint nebulosity with seems to connect it to IC1318A. There is so much nebula in the area, and the distances to them are indeterminate, so it might just be a trick of they eye to believe they are connected. Photo Ron Brecher.
I poked around in the Cygnus area for quite a while, sharing views with others -- really dramatic area. I switched to 1x using the mirror mount too, and was struck by all the nebula in Cepheus, which has plenty of nebula to keep one busy. So starting from the earliest Sharpless object, I continued:
Sh2-128: = Abell 77. 21 32 08.4 +55 51 34, 1' diameter. 8-inch and Ha. Small bright knot around a star, split by a faint dark lane nearly E-W. Distance: 9400 pc, Size: 2.7 pc. Vogel notes "This region is actually located at a distance of 9.4 kpc, is about one million years old and is ionised by an O7 star."
Sh2-129 & Outters 4: 21 11 44.4 +59 57 40, 140' diameter. 400pc distant, 16.3pc in size, the Sh nebula is best in the 4-inch and Ha, with a bright, very mottled C-curve pointed NW, and many long faint streamers trailing away from it. The middle portion is filled with faint nebulosity. Outters 4 is a recently discovered nebula which has a bipolar outflow, a very curious and beautiful shape. Outters has a website to describe his discovery. I made a very (very) marginal observation a couple years ago at CalStar using a 10-inch f3.7 and OIII, but really all I saw was a suspected nebulous streak among the bright stars at the center of the lobes. This time, with 8-inch and a dual-band Ha and OIII filter (5nm), I spent a good long while on the region and believe I detected the lobe to the south, and part of the glow to the north. It was a extremely faint elongated glow with brighter edges. My field sketch lines up with the field stars and the lobe correctly points to a bright wall of Sh2-129. I definitely want a better night to go after this one again.
Sh2-130: 20 42 59.6 +63 13 43, 3' diameter. Very faint, difficult in both the Ha and dual band. Weak diffuse flow offset to the southwest from a bright star, small. Vogel: Distance: 600 pc, Size: 0.5 pc, "Faint nebulosity surrounds the B5 star HD 197911, the A0 star HD 197809 and the G5 star SAO 18999. HD 197911 is a runaway star blasted from the heart of the Cep OB2 association by a supernova explosion 2-3 million years ago."
Sh2-131: 21 39 00.2 +57 29 10, 170' diameter Best in 4-inch for overall view, 8-inch provided detail of dark nebula, the elephant trunk, etc. Showpiece. Vogel: "Distance: 860 pc, Size: 42.5 pc. "Sh 2-131 surrounds the star cluster IC 1396 and lies at the heart of the Cepheus bubble, the giant expanding shell of gas and dust around the Cep OB2 association."
Sh2-132: 22 18 47.0 +56 08 05, 90' diameter. Bright, large, and heavily mottled & streaked with dark nebula, overall curved shaped, runs through string of stars, with long tail of diffuse nebulosity extending to the south. Best with 8-inch and dual band filter. Vogel: Distance: 3180 pc, Size: 83.3 pc, "This giant HII region in the Cepheus OB1 association is ionised by two WR stars and several OB stars. HD 211853 (WR 153) and an O 8.5 star lie near the middle of the radio shell associated with this nebula."
Sh2-133: 21 28 59.8 +64 18 19, 80' diameter. Very faint region of nebulosity, appears as a sheet of rain-falling cloud within a triangle of equal magnitude stars, with a brighter wide streak trailing to the SW, and a fainter extension sweeping up from it to the north. 4-inch and Ha. Vogel: Distance: 800 pc, Size: 18.6 pc, "Sh 2-133 is probably a part of a chain of ionized arcs surrounding the older group of the Cep OB2 association and is located at a distance of about 800 pc."
Sh2-134: 22 11 29.1 +59 24 37, 160': Unorganized region of bright knotty nebulosity in the star field, all with diffuse edges, one faint cloud near a bright star has with sharp curving cut-off, likely from a dark nebula. 8-inch & dual band. Vogel: Distance: 900 pc, Size: 41.9 pc, "This HII region is associated with an expanding bubble in Cep OB2. Also involved with this bubble are the HII regions IC 1396 (also called Sh 2-131), S129, S133, and S140. Lam Cep (HD 210839) is the exciting star for this HII region.
Sh2-135: 22 22 11.0 +58 44 18, 15' diameter. Fairly easy, bright arc above star which is involved in the nebula, with a sharp cut-off to the north; other faint diffuse nebula to the south. 8-inch Ha. Vogel: "Distance: 1400 pc, Size: 6.1 pc. This is probably a blister on a dark dust cloud in front of the bright nebula. The nebula is ionised by an O9.5V class star and located at a distance of 1900 parsecs."
Sh2-137: 21 57 06.6 +64 41 37, 90' Wall of diffuse nebula with a rather distinct cut-off to the SW. Vogel: Distance: 600 pc, Size: 15.7 pc. This HII region lies at a similar direction and distance as the Cepheus Bubble, a huge expanding shell of gas and dust surrounding the Cepheus OB2 association. Avedisova places Sh 2-137 at a distance of 700 +/- 300 parsecs and identifies 5 ionising stars. The hottest of these is the O9.5 II giant and double star HD 207198."
Sh2-138 (22 32 39.0 +58 28 55, 1' diameter) & Sh2-139 (22 32 39.0 +58 28 55, 1'): In the same field, large triangle of stars. Sh2-138 is very small and really just a smudge of nebulosity around one of two close stars, centered in the below image. Sh2-139 is the larger mist of diffuse nebulosity near the southern star of the triangle. 4- and 8-inch, Ha. Of Sh2-138 Vogel says: Distance: 4000 pc, Size: 1.2 pc. "Embedded in this compact HII region is a large star cluster resembling the Orion Trapezium cluster: it is centrally peaked around several massive stars, and is dense - more than 550 stars at its centre." Sh2-139, on the other hand, only Distance: 3300 pc, Size: 24.0 pc
Sh2-140: 22 19 07.0 +63 17 07, 30' diameter. Bright small arc of nebulosity with a sharp cut-off to the NE, and to the west there is a cluster of bright stars and diffuse nebula expanding faintly to the west. 8-inch Ha. Vogel: Distance: 900 pc, Size: 7.9 pc, "Sh 2-140 is created by the B0.5 V star HD 211880 exciting the southwest side of the L1204 molecular cloud."
Sh2-141: 22 28 30.4 +61 38 41, 5' diameter. A small circular puff of nebula, irregularly bright with diffuse edges, in the middle of an elongated triangle of similar magnitude stars. 8-inch Ha. Vogel: Distance: 6700 pc, Size: 9.7 pc. "The faint circular HII region Sh 2-141 lies far away at a distance of 8340 ± 600 parsecs according to Russeil. Pineault and Joncas give a distance estimate of about 7000 parsecs and suggest that Sh 2-141 may be ionised by a single O8 class star."
Sh2-142: 22 47 35.1 +58 03 39, 30'. Quite amazing and dramatic. Bend of rippled dark nebula with penninsulas (not quite pillars) jutting into bright diffuse glow, very like the Eagle Nebula. The more one looks the more detail seen, subtlties in the shapes of the dark nebula. Contains NGC7380, a young open cluster of stars in the northern circumpolar constellation of Cepheus, discovered by Caroline Herschel in 1787. Vogel: Distance: 3537 pc, Size: 7.2 pc, "This HII region, entwined with the star cluster NGC 7380, contains 4000 solar masses of gas and is ionised by the eclipsing binary star DH Cephei (O6+O6). It is associated with a molecular cloud containing an additional 6-15 thousand solar masses of gas, and the star cluster NGC 7382, which are all part of the Cepheus OB1 association."
Sh2-143: 22 50 14.8 +57 42 47 4' diameter. The is a very small, very faint puff of nebulosity off the southeastern coast of Sh2-142 and should probably be considered part of that structure (it has a similar distance). 8-inch Ha. Vogel: Distance: 3700 pc, Size: 4.3 pc. "According to Avedisova, Sh 2-143 is ionised by the O9.5V star LS III +57 93. Sh2-142 is NW of it."
Sh2-144: Fairly bright small puff of irregularly bright nebula with diffuse edges. 8-inch Ha. Not much to look at, but per Vogel: Distance: 800 pc, Size: 0.9 pc. "Both Sh 2-144 and Sh 2-146 appear in the direction of the 377 thousand solar mass molecular cloud [UUT2000] Cloud B. Sh 2-144 appears to lie well in front of this cloud, however, and is associated with the local Cepheus clouds. No ionising star for Sh 2-144 has been identified in the scientific literature. Avedisova associates this nebula with the pulsating variable carbon star MV Cep."
Sh2-145: 22 25 33.0 +64 18 31. 90' diameter. Large diffuse & tattered expanse of nebula, with a sharp cut-off between it and Sh2-131 which is SW in the same 4-inch field. Vogel: Distance: 900 pc, Size: 23.6 pc. "Avedisova identifies 4 ionising stars for Sh 2-145, including two O-stars: the O7 V star BD +62 2078 and the O9 V multiple star HD 213023. Sh 2-145 appears to be part of the Cepheus bubble, the expanding ring of gas and dust surrounding the star cluster NGC 7160 and the Cep OB2 association. The much brighter nebula Sh 2-131 is part of the same structure."
Sh2-146: 22 49 25.5 +59 55 45, 2' diameter. Small, round, bright divided in two by a curving dark lane E-W, in a wide triangle of stars with curved dark nebula, 8-inch Ha. Vogel: Distance: 5483 pc, Size: 5.9 pc. "This HII region is split in half by a dust cloud and is excited by a highly obscured O7 star."
Sh2-147/148/149/152/153: 22 55 29.2 +58 28 01, 2-5' diameter. All together in the same field of view, small puffs and wisps of nebula in a fairly rich field. 153 is comparitively large, swirling circle of nebula with wisps coming off the east and west edges. 152 is very compact and bright, as is 148. 147 is very faint and wispy, and 149 is the most difficult of all (needed 8-inch), a very small smudge around its star. Per Vogel, these are "all parts of the same giant molecular cloud located at a distance of about 4500 pc."
M57 & central star: This was the last object I tried for the night. With the crescent moon risen ~15-degrees in the east, it produced a glow similar to the light dome Santa Rosa cast. So I tried for targets in the west which was still fairly dark. I had read M57 was a good target for night vision, and it was. in the 8-inch, unfiltered, and despite the small image scale (with a 22mm Nagler the magnification is only 55x), I saw a surprising amount of detail: the annulus or ears on either end, bright knots scattered around the ring, with very thin gaps along the edges of the ring to make it look like two shells, and especially the center of the ring filled with thin, streaky gause. I tried pretty hard for the central star. I could see the 15.0 and 14.7 magnitude stars just outside the NE edge of the ring (shown in this image--which also shows the knotty detail, especially along the SW edge of the ring, I described). The central star revealed itself several times over a few minutes period, and only when I would look away from the nebula then look back: the central star would be a slightly hazy point which would hold for a couple seconds then fade. Not quite a slam dunk, but pretty amazing for only 8-inches aperture.
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