by Robert English
The Clearsky clock, I might add, showed a cloud out for Mt. Tamalpias State Park, and I wondered about this as I pushed the 18" dob towards the 37% moon. They must be talking about the sea-level conditions, I thought. Between 6 and 7:30, I was joined by Peter Schumacher, Russ Cashin, Jennifer Myers, Darrell Lahman, Stephanie Ulrey, and others.
The first thing I noticed was that the moon's image, still framed by blue sky, was not shimmering. How odd. We located Jupiter against a blue sky--it's sort of an unofficial contest in SFAA to see who can locate Jupiter first using binocs and naked eye. Russ Cashin nailed it in a few seconds. At 60x in my dob, it showed an unusual amount of detail. I was able to count six definite bands, and at 120x, eight. I am by no means an accomplished planetary observer, but I know what I like, and I was liking this. The level of detail visible was abnormal, in my experience, especially during daylight. It wasn't long before Rock Springs was echoing with "Wow!"'s and "OMG"'s. (We're a vocal group of observers. ;-)) Ganemede was showing a clear disk, though at times it would shimmer slightly. In my scope I was seeing Io (disc), Jupiter, Eur (appeared stellar), Gan (disc) and Callisto (stellar). The southern zones of Jupiter's disc offered many "barges" and other rarely seen markings. What could account for the level of detail? I thought it might be that because we were viewing in a bright sky (still blue-ish) that our pupils may be contracted, cutting the glare of the usually bright Jovian disc, and making all the other more subtle features stand out. If this was the case, after dark, we should not expect to see this level of detail. But after sunset, the detail remained.
My guess is that the high, thin cirrus indicated stable temperatures (stable but cold) aloft, and what we were experiencing was the oft-described wonderful seeing that preceeds an upper level troff. Yes. It really happens, and when it does, it's wonderful. I've heard an approaching ridge can produce the same good seeing.
We all enjoyed wonderful views of Saturn as well, even though it was not optimally placed for viewing. I was able to see two bands on the disc, the cassini and encke (in and out) while it plunged toward the horizon at 120x. A pretty decent view for so late in Saturn's year.
The moon, at 37% illumination, was remarkable. There was a virtual absence of any atmospheric distortion. I would describe its appearance as photo-realistic. Images held up past 300x, finally fuzzing up at 580x. I could live with that, thank you very much, and spent nearly an hour cruising the lunar surface, something I rarely do.
When the public viewing began, our visitors were treated to exceptional (for Mt. Tamalpias) views of the gas giants and moon, and we even threw in a few bright galaxies before the stratus clouds choked us out at 10:30.
The reason I write about this pretty ordinary star party is that it is a case of something good coming out of an event that had "stay home" written all over it:
A horrible looking ClearSky Clock. (A mass of grey and white boxes--looked like the loading dock at Nordstrom) NWS forecasting a cloud-out (which happened, but later in the evening).
A history of clouded out Star Parties stretching back a year.
Lots of fog and wind at lower levels.
A 37% moon.
Posted on sf-bay-tac May 15, 2005 01:05:03 PT
Converted by report.pm 1.2 Sep 20, 2005 12:31:26 PT