12:20 a.m. 12 January 2007 PST (2007–01–12–0820 UT)
Been a while since I last observed with Opus (check my observing log to see just how long), so I decided to set up around midnight. Started with M42 just to warm up. What a fantastic object this is! It was well situated for low-power observing, toward the southwest, where light pollution—as seen from my backyard—is at a near minimum. (It is over the house, though, so high-power observing is iffy in this area of the sky.) Even here in Santa Monica, there's enough darkness to see the hawkish shape of M42 spread its wings over nearly a degree. This was at 32x, using the 24 mm Panoptic with the f/6.3 reducer. I put in the 6 mm Radian for 125x to try to identify the E or F stars in the Trapezium, but the seeing didn't support it—probably owing in large part to the currents from my house.
Further up from M42 is M35, one of my favorite open clusters. Stashed away in the northwestern corner of Gemini, at Castor's feet, M35 is wonderfully layered, with stars of seemingly every degree of brightness from the seventh magnitude on down. This gives it a vivid sensation of depth, so that even with a single eyepiece, one gets a strong impression of three-dimensionality, something that is only further enhanced when seeing it in a binoviewer. To the southwest of M35 is NGC 2158, another open cluster, similarly rich, but several times further away, so that it has a smaller and more powdery appearance under dark skies. In suburban skies with a 5-inch scope, the challenge is merely to detect it. It lies near a four-star pattern; I thought I glimpsed it a couple of times as a small hazy patch, but it's pretty hard to tell for sure.
Back lower in the sky, but further east, is M41, the grandest open cluster in Canis Major. It is pretty easy to find, especially when near the meridian, since it is just a few degrees south of Sirius. M41 is fairly easy to see in the finder, even under bright skies, provided one knows where to look. It too elicits a sensation of depth, but one less impressive than with M35; it seems to have just two layers of stars—one at the eighth magnitude or so, and then another at the tenth. It's praising with faint damns, however, to say that it's inferior to M35; it's still a wonderful sight.
I tried a spot of planet observing with Saturn, which is near Regulus these days, and which caused me to have problems identifying Leo, since that constellation was rising in the east and was partly lost in the Los Angeles light dome. The view was tolerable, but not nearly detailed enough to satisfy. The Cassini division was fairly easily seen but indistinct. I moved on to M67, an underrated open cluster in the constellation of Cancer the Crab, and which is often overshadowed by its nearby cousin, M44, the Beehive, aka the Manger, aka Praesepe. (In fact, my astronomy web server used to be an alias for praesepe.isi.edu.) M67 is a fine open cluster, with a paucity of bright stars, but is richly littered with dimmer ones. It seems to me to have a broad band of brightness running from the northwest to the southeast. Do you see this?
I try to include, in each observing session, some object that I've never seen before, and fittingly, my choice for this night was yet another open cluster, NGC 2360. Located just a couple of degrees east of the head of Canis Major, NGC 2360 appears as a compact ball of stars, with a noticeable gradient toward the center, and fairly symmetric. I picked this out of the Night Sky Atlas, but I had trouble deciding which of two groupings of stars was the right one, this one, or another looser one to its northeast. I finally settled on the correct candidate, as confirmed by PleiadAtlas. The other grouping doesn't appear to have a designation that I'm aware of; it's located about 20 arcminutes to the northeast. If anyone knows of a catalogue in which this small grouping appears, I'd be interested in hearing about it.
Copyright (c) 2007 Brian Tung