Excellent conditions at Lake Sonoma last night!

by Steve Gottlieb

Sounds like conditions at Fremont Peak were very similar to what we had at Lake Sonoma last night. I drove through the lush Sonoma County vineyards as the sun was setting and casting a warm golden shine over the wineries and hills. Once we arrived I was pleased to find Lake Sonoma quite warm (no jacket all evening), completely calm and very dry. As Peter mentioned at Fremont Peak, seeing was excellent -- as an example here's my observation of NGC 7662 (the Blue Snowball) at over 800x (afterwards, I then jacked the magnification up to 1087x!)

18" (10/19/06): In steady seeing, the double-shell structure was remarkable at 807x (7mm Pentax + 2.5x Powermate). The outer envelope was noticeably oval SW-NE, ~35"x25". Embedded within this envelope is a fairly thin, very bright inner ring with a sharply defined outline. The ring was irregular in surface brightness but clearly brightest at the SW and NE ends of the ring (ends of the major axis). The ring faded on the NW side and there was a small, distinct gap in the ring at the NW end. The surface brightness of the inner ring was high enough to give a glowing "electric" quality with an impression of a rope-like or twisted structure. The center of the ring was much darker than the ring and formed a substantial dark oval at this magnification, but was still clearly luminous.

M76, the Little Dumbbell Nebula, was also quite impressive --

18" (10/19/06): superb view at 225x using a UHC filter. The main bi- polar body was very bright, elongated ~SW-NE and dominated by two large, irregular knots at either end. The SW knot is brighter and surprisingly is more elongated in the direction of the minor axis. Both knots are somewhat irregular in shape and brightness. A mg 13.5-14 star lies just off the SW end. The two bright knots are attached with a fainter bridge of nebulosity. Extending off the north end is a large "arm" that sweeps around towards the west and a slightly less obvious counterpart is attached at the south end and sweeps towards the east. The overall effect mimics a photograph of a barred spiral galaxy or perhaps a rotating sprinkler head with jets of water curving away.

BTW, Comet Swan was on the threshold of naked-eye visibility, so if you haven't seen it yet, this weekend is the time.

Steve Gottlieb

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