10 Dec 2007 Lake Sonoma

Carter Scholz

Transparency pretty good, a few bands of clouds visible in the south and southeast; seeing mediocre, lots of scintillation. Steve pointed out the zodiacal light, which I might have mistaken for part of a light dome, except that there is no artificial light in that direction. Comet Holmes, now hardly visible naked eye in Berkeley's light pollution, remains very striking here. In brightness and size it's comparable to the nearby Double Cluster. Brighter than M31. Easily over a degree across, almost too big for my 34mm eyepiece, and not pretty under this magnification, looking like M31's core.

Right away I found that I'd made the same bonehead mistake as on my last trip here with Greg La Flamme: left my light baffle at home. The light dome of Santa Rosa was visible through the eyepiece, behind the diagonal and the unshielded upper ring, washing out the view. Last time Greg bailed me out with a piece of foam. This time I had a piece of my own, and Steve offered me some flocking material he had with him. I wedged my foam in place and that took care of it. Since the foam is part of my transport packing, maybe I should just let it become the baffle.

Steve worked on M31 globulars and M33 HII regions with his 18". That's a really intriguing project. I know Bill Cone's been working on it too. I found labeled plates of these objects in Luginbuhl & Skiff and in NSOG, but the scale and quality don't look usable at the eyepiece. I'm guessing that Bill and Steve have printed up their own DSS charts, but I'm curious about available resources for this project.

Steve showed me one of these objects -- G229? -- a mag 15. I had only a suspicion of it until Steve removed some glass -- took out the Paracorr and replaced the Nagler with a Tak eyepiece with fewer elements; then I could hold it in view. Especially given the seeing, there was no telling it from a faint star without a chart.

I've been trying to get comfortable navigating galaxy groups and "reading" DSS images at the eyepiece, so I returned to the Pegasus cluster, Abell 426, to refamiliarize myself and perhaps pick out some more members. I mistook the field and found myself looking at 1245 instead, a pretty, rich, faint open cluster very near the comet, a Herschel object I've observed before.

Moving to the proper field, and starting from the brightest member, 1275, I worked outward, and found exactly the same nine I had found last time at Lake Sonoma with Greg: 1275, 1277, 1278, IC1907, 1273, 1272, 1270, 1267, and 1268. At least it was a bit easier this time.

Another project I've been pursuing is Milky Way globulars. Winter isn't really the season for it. After Steve's advice that Pal 13 was probably unattainable with my aperture, I tried for Pal 2 with no luck. A little later Steve went after Pal 1, and the two of us spent some time studying DSS plates of the field. We had the field for sure, but neither of us saw a thing where the globular should be.

A brief look at Mars showed that seeing was too poor to spend any productive time there.

I went to a rich galaxy group that (I believe) has no Abell designation. It's midway between Mirach and M33. I started near a far edge only because I happened on a recognizable asterism there. 536 is elliptical, bright, easy, making a near equilateral with two field stars mag 6 and 7. 529 equally bright, spherical, 10' to the east. I couldn't detect 531 and 542 which flank 536. Moving southwest, saw 561. From here I cruised SE a degree over a fairly empty area ("empty" is a relative term -- only 5 galaxies charted in Uranometria and a paucity of field stars) to an obvious pair of stars about mag 8 and mag 10 that served me as a good "home base" in the denser part of this cluster. Very nearby them is IC1687, unseen at first; I had to come back to it. The most prominent member here (or the one I saw first) is 507, and nearby 508. From here one can spiral out to 504, 494 (both dimmer and more elongated). IC1682 and IC1680 should extend this chain but I didn't see them. On the other side of the "home pair" stars, 503 is nearby, and continuing outward (north) are 501, 499, 498, 496, 495 in a tight group. About 30' east, past another dimmer star pair is 483 and IC1679. Steve was picking out globulars in the Fornax dwarf. After checking out 1049 in his scope, I went to acquire it in my own. He kindly lent me a chart and came over to confirm it.

Near midnight Steve packed up. He pointed out what could have been the gegenschein, a band of slight brightening about ten degrees wide passing about five degrees south of Aries thence into Taurus just north of the Hyades. I doubt I would have seen it if my attention hadn't been drawn to it, and even then I wondered if it might be an optical effect caused by the distribution of stars. But after checking the actual path of the zodiac -- exactly that line -- I think it was for real. So, two observational firsts for me thanks to Steve: the gegenschein, and an extragalactic globular.

I stayed just a bit longer, poking around in Orion, which by now had moved clear of the Santa Rosa light dome and was stunningly beautiful. I failed to see the Horsehead (no filter), but saw unmistakable nebulosity in 2174/2175.

The thin sunset clouds in the southeast thickened just a bit after dark and increased the brightness of Santa Rosa's light dome, but after about 2100 they vanished, and by midnight the sky was pristinely transparent, though seeing remained soft and even worsened. The ground air was mostly still all evening, though even so often a steady 5 mph breeze came up, with some strong gusts. Temps were around 40 and humidity remained low. A very pleasant evening. As the drive home reminded me, even a half-night of winter observing is a good long time.