OR: Lake Sonoma on Saturday 1/13/07

by Steve Gottlieb


On Saturday night Bill Cone, Matthew Marcus and I boldly took the challenge to brave the predicted cold conditions and headed for Lake Sonoma under what appeared to be mostly clear conditions in the afternoon. Bill and I stopped for dinner in Healdsburg and then caravanned the rest of the way up to Lake Sonoma as the sun as setting and the numerous Sonoma County wine vineyards nearby were turning a golden hue. At first it looked like the weather was going to mock our efforts as wispy clouds soon turned thicker and covered the entire area as it was getting dark. But around 7:00, the curtain of clouds started to be pulled open and in a short time we were looking at completely skies.

After this brief early interlude of clouds, sky conditions were excellent -- although cold, the air was perfectly still and dry and the transparency was quite good for Lake Sonoma. I brought along my new 80mm Stellarvue finder (F80) and was quite pleased with the widefield views and the star images. Using a 24mm Panoptic the actual field was just over 5 degrees at 13x and sharp from edge to edge! This low power/wide field combination gave an excellent view of the California Nebula (most contrasty that I remember seeing) as well as a clear view of Barnard's Loop using an H-beta filter as a wide river of nebulosity flowed through the entire 5 degrees! Thor's Helmet was a very easy target using an OIII filter. Finally, in the finder I confirmed an earlier 80mm sighting of the Medusa Nebula (Abell 21) using 13x and OIII filter. This was not a difficult observation with averted vision.

California Nebula (NGC 1499): Using a 24mm Panoptic and H-beta as a huge, elongated bar of fairly high contrast stretching across the 5 degree field. The glow was generally brightest in the broad middle section between Xi Persei and the 6th magnitude star off the central north side. The nebula noticeably tapered towards the southeast end as the northern side of this end squeezed inward. Similarly, the northwest end also tapered as the northern boundary narrows towards the southern side.

Barnard's Loop (Sh 2-276): 13x80mm (1/13/07): easily visible extending through the entire 5 field of the 80mm finder at 13x (24 Panoptic) using a H-beta filter. With NGC 2122 centered in the scope, a gently curving band of nebulosity of width 30' extended edge- to-edge over the field and could be traced an additional degree or two beyond by slowly panning. I was previously aware that the region around NGC 2122 was pretty contrasty at low power, but I also found a locally brighter patch at the north end of the Loop (my digital setting circles read 5h 47m +01.3) including three brighter stars. To the south, I could follow the arc to where it passed a bright star at -03 degrees dec and ended about a degree further south. The total length followed was roughly 6 degrees.

In my 18-inch Starmaster I focused on a few clusters -- Abell Galaxy Cluster (AGC) 569 in Lynx with brightest member NGC 2329 (9 galaxies viewed in total) as well as the NGC 2389 group in Gemini. I last time I had looked at the NGC 2389 group was back in 1985 with my old 13.1" Odyssey I so it about time for a return visit. On the other hand I observed AGC 569 from Willow Springs just a couple of months back (11/18/06) but had forgotten about the observation! Despite the apparently darker skies at Willow Springs, my descriptions ended up amazingly similar and I was able to view all of the objects I had picked up at Willow Springs and a couple of additional ones that I hadn't look for before. Bill Cone and I also made a dual assault on all the main galaxies in the Beehive cluster. Some of these I had observed back in 1997, but others were first time observations. Finally, I went through the field of reflection nebulae in Monoceros that includes N2170, 2182, 2183, 2185 as well as vdB 68 and vdB 69. We kept observing until 1:30 logging over 40 objects.

AGC 569: This Abell cluster may be connected to the great Pisces/ Perseus Supercluster on the opposite side of the Milky Way. At the very core I picked up four galaxies -- NGC 2329, UGC 3696 and MCG's +08-13-072 and -082, though the MCG's are much fainter. Scattered around the core are a number of faint galaxies and 9 were viewed in total.

NGC 2329 group: This galaxy group contains 7 NGC galaxies and a couple of additional members that were even missed by Lord Rosse with his 72-inch from Birr Castle in Ireland. The group is very elongated -- really a string of galaxies somewhat like the NGC 383 group (Pisces Group) -- beginning on the west end at NGC 2373 and continuing east to NGC 2375 and 2379 and then on to the core which contains NGC 2385, 2388 and 2389. Further NE you can find NGC 2393. The two dims ones that Lord Rosse missed were CGCG 177-019 and UGC 38979. If you're a fan of galaxy clusters, this one is not too difficult in 12-inch and larger scopes but none of the galaxies showed any interesting structure. The brightest member, NGC 2389, was described at 280x: "Moderately bright, fairly small, oval 5:3 ~E- W, ~1.1'x0.7'. The outer halo fades into the background gradually so it's difficult to trace with averted vision. The halo has a broad, weak concentration with no well-defined core althought there is a small brighter nucleus with direct vision. Forms a trio with NGC 2388 3.4' SW and 2385 7.7' WSW.

Beehive Cluster galaxies: Yes, there are a number of faint galaxies hiding among the bright stars of the Beehive (M44). Bill and I confirmed our observation of 8 of these elusive galaxies. Five have NGC numbers, 2624, 2625, 2637, 2643, 2647) and were discovered by Albert Marth using a 48-inch f/9.4 reflector from Malta (see http:// www.klima-luft.de/steinicke/ngcic/persons/marth.htm to have a look at this behemoth scope). With some effort we also identified CGCG 89-056, IC 2388 (discovered by E.E. Barnard) and UGC 4526. The easiest of the lot are the pair NGC 2624 and 2625 on the west end. NGC 2624 was described as "fairly faint, small, round, 25" diameter, weak concentration. A mag 15.5 star is close SW. Brighter of a pair with N2625 located 3.2' ESE. Situated on the NW edge of the Beehive cluster." My notes for NGC 2625 read "faint, very small, round, 15" diameter. Smaller and fainter of a pair with N2624 3.2' WNW, though the difference in brightness appears less than the 1.4 magnitudes listed in catalogues." This was using 280x in my 18-inch (7mm Pentax XW).

NGC 2170-2185 Reflection Nebulae: Just west of 4th magnitude Gamma Monocerotis is an interesting group of reflection nebulae mostly surrounding 10th magnitude stars. No filters are necessary as the glow is mostly reflected light off dust particles. From west to east here are my descriptions;

NGC 2170: Fairly bright, moderately large reflection nebula surrounding a mag 9.5 star, ~2.5' diameter. There are two stars bracketing the nebula at the north and south ends with the brighter southern star 10th magnitude. Reflection nebula vdB 69 lies 8.5' ENE.

vdB 68: moderately bright, large reflection nebula surrounding mag 9.6 HD 42004 and encompassing two mag 11 stars 1.5' NE and 3' NE. The shape appears irregular and ~5' in size.

vdB 69: moderately bright, large reflection nebula surround a mag 9.5-10 star. Extends mostly SE of the star, ~4'x2'. Located 8.5' ENE of N2170 in a group of RN.

NGC 2182: bright reflection nebula, round, ~2' diameter, surrounding 9.3 HD 42261. In a group of reflection nebula with N2170 28' WSW and N2183 20' ENE.

NGC 2183: fairly faint , appears ~1' diameter and notably was *not* surrounding a bright star as are the other nebulae in the group. There appears to be a faint star, though, at the south edge which may be the illuminating star. A much larger complex of of nebulosity including N2185 is less than 5' E and SE.

NGC 2185: faint, fairly small, 1' reflection nebula surrounding a mag 12-12.5 star. This glow is a few arcminutes NE of a group of 4 mag 12 stars which are also encased in a larger 3' haze of weak nebulosity. Both of these pieces are part of N2185. Located 5' E of N2183.

Around 1:30, after logging over 40 objects, we all decided to call it quits. All in all it ended up a delightful evening and well worth bundling up to keep warm in the cold conditions.

Steve


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