Lake Sonoma 12/08/07

Bill Cone

Early on, Comet 17P Holmes was running neck and neck with the Double Cluster as a nice naked eye object in the Northern region of the sky. Whether viewed naked eye, in a finderscope, or the eyepiece, the comet had a great deal to offer. Since coming to our attention a few months back the comet has continued to grow, and visually, the main body of the coma is nearing 1° in diameter, with a soft fading extension of perhaps another degree. The comet is currently in a very rich field of stars, including V509, a mag 6.4 variable star found on chart 43 in Uranometria. The brightest aspect of the comet is a parabolic form, with a discreet edge to NNW, and a very diffuse edge trailing off to the SSE. While re-acquiring the comet, I noticed a suspicious 'smudge' in the eyepiece about .5° to the S, and went to Uranometria to find what I was I was seeing. Turned out to be NGC 1169, Ga, 11.7v. The chart showed other galaxies even closer to the coma, but, though I was capable of fooling myself, I could not pinpoint any other galaxies closer in. The real delight of the comet, besides it's discreet and diffuse edges, was how many bright field stars it's coma overlapped. The finderscope showed at least 12, while the main scope showed more than I cared to count.

Though the seeing was a bit wobbly, Steve and I managed to observe between 200-300x, picking out numerous clusters, associations, and HII regions in 2 Messier galaxies for a great deal of the evening, M-31, and M-33. As M-31 had passed the meridian by the time we started, the galaxy had rotated quite a bit since my last observing session. The prominent dust lanes were now on the left side of the field, as I slowly panned up the West side of this massive neighbor, traversing 60,000 light years in a matter of seconds, eventually coming upon NGC 206, a huge extended star cloud on the Southern end. Working with charts in hand, at our respective eyepieces, we revisited some of the objects I had logged at Dino last month, discussing our impressions as we went. Some of the faint globulars behaved like small planetaries, growing slightly with averted vision, then reducing to a small soft dot of light, revealing their non-stellar nature in this manner. G76 was bright enough to make this sort of an impression, while G52 was an averted vision only object, that one would never find unless you knew exactly where to look in the field. As we went on, some of the objects were so faint that averted vision only registered the object periodically, something I've read in other people's ORs more often than I had experienced before. On this evening, many of the objects were low percentage averted vision targets. However they would faithfully reappear in the same spot with patience, and getting the eye in the right position. I also found that after acquiring some of these objects, they would be flickering into view, while I was looking for other objects nearby. I logged 9 objects in and around M-31, which included 2 UGC galaxies in the region of G1. UGC 338 was one of these, an edge on that would periodically pop into view like a phantom grain of rice.

I took a break from the faint stuff, and moved onto some larger objects for awhile. Greg LaFlamme had been singing the praises of NGC 7479 in Pegasus, so I went there. Unfortunately, it was pretty low on the horizon, and the subtle detail of the barred spiral arms was invisible. The galaxy looked like an edge on with a soft glow around it, the edge on element actually being the central bar. It is conveniently situated between two field stars, oriented N-S, with the Northern end of the galaxy tangent to the Northern star.

Next up was NGC 247, below Cetus. This galaxy was much larger than 7479, and had the same N-S orientation, with a prominent field star on the Southern tip. The galaxy appears to fan out to the North from this star, fading out considerably once it passes the central core. I was interested in this galaxy because it was a signpost to the Burbidge chain, a small string of 4 faint galaxies running N-S about 18' to the NW of 247. I was not patient with this, and only detected one galaxy, M-4-3-10, mag 13.7, on the Northern end of the chain as an averted vision smudge South of a star.

An odd frustration was an attempt to revisit the Fornax dwarf globulars. At that time in the evening, it was not ideally placed, and neither of us could find the right field to work from. I just don't know that region of the sky well enough to hop right to it, and I may have picked the wrong stars to start with.

Steve suggested moving to M-33. I hadn't studied this since last year, when I logged objects on the North and West side. Starting at NGC 604, we worked our way South, down the East side of the galaxy, even picking out an 'anonymous' HII region that was brighter than some of the labeled objects in the neighborhood. We spent perhaps 90 minutes to 2 hours on this project, discussing the objects and the field. Steve often would acquire the object before I could, and was very good at describing exactly where to look. That in itself is an acquired skill, as I often found myself fumbling to communicate directions, while Steve could verbally organize the field quite rapidly. Give me another 27 years... I went after C39, the only globular I had on my chart, and could not see it, though it is pretty easy to know exactly where to look due to the nearby field stars. The character of the objects viewed ranged from small bright patches, to dim extended glows, to small faint dots, to barely-there-with-averted-vision glows. A minimalist buffet of sorts. We eventually circled about 3/4 of the galaxy before calling it quits. Of these objects and regions, the most interesting structurally were 3 IC objects, 139,140 and 137, which comprised the bright regions of a Southern arm jutting out from the SE corner of the nucleus. IC 139 and 140 are stacked N/S, with 140 being the elbow, where the arm turns WSW, with IC 137 being a bright region at the end of the arm ~5' away. An easy catch was A48, a small association South of the nucleus, comprising a non-stellar 4th member at the W. end of a string of 3 equally spaced stars running to the SW. I came away with notes on 19 objects. Some of these Messiers are rich in targets of their own. M-33 and M-31 rank right up there in this regard. I used an 11mm Nagler in this survey giving me 198x.

A very cold breeze began to blow, and I was getting pretty tired after concentrating that long on some fairly dim targets. I took a quick peek at the M-42 region before packing up. Gorgeous. All viewed through a Plettstone 18" f4.2 reflector with a Paracorr.

-Bill Cone