Lake Sonoma Sunday night 3/11/07

by Steve Gottlieb

With warm spring-like conditions on Sunday and a very encouraging CSC I put out an observing intent around noon on a couple of mailing lists and was pleased to have two quick positive responses for Lake Sonoma from Matt Marcus and Matt Tarlach. With daylight savings time in effect, I didn't have to leave until after 5:00 but with an early class to teach on Monday this would have be a somewhat abbreviated evening.

When I arrived at 6:45, Matt M was already set up with his C-8, but I was disappointed to find a maze of thin, high cirrus obscuring much of the sky. Would it dissipate as the temperatures dropped or spread out and frustrate viewing? During twilight Matt T showed up, set up his 80mm refractor. As I looked at our line-up of 3.1-inch ED refractor, 8-inch S-C and 18-inch dob, we seemed to pretty much cover the gamut of amateur scopes.

For the first hour and a half of darkness, a veil of clouds was quite evident in the north and south, but the darkest location at Lake Sonoma to the southwest and west was clear, so I took at look at several objects in Canis Major, Orion and then Puppis. By 10:15, the veil had lifted over the entire sky and the hunt was officially on for galaxies. Over a period of nearly 3 decades I've been systematically chasing down the complete NGC (7840 entries) and have whittled the list down to 150 objects visible from our latitude. Naturally, most of these are springtime galaxies -- that season slips away from us so quickly as the nights continue to shorten. So, for the rest of the evening I was scurrying around Cancer, Leo, Sextans, Hydra -- hunting for dim blobs in the eyepiece and some occasional eye candy to break up the monotony.

During one of those breaks I took at look at an obscure open cluster -- Biurakan 9 (also known as Berkeley 32) in Monoceros and was surprised to find a rich, pretty cluster at 160x. The short list of Biur clusters were discovered by Victor Ambartsumian, the director of the Byurakan Observatory (located on top of Mt. Aragats in Armenia) in 1949. The cluster consisted of roughly 60 stars mag 12 and fainter (most were mag 14-15) in a 5' to 6' group set within a rich star field. The background glowed from faint, unresolved stars. A number of bright stars were nearby including a mag 7.7 star about 7' NNW of the center. Several additional mag 10 star immediately to the west and east surrounded the cluster and a vivid mag 7.5 orange star 16' SSE had three faint companions. Biurakan 9 is an ancient cluster with an age of ~6.3-8 billion years.

As far as the NGCs, one interesting object I looked at was NGC 3217. You won't find this entry in most atlases or databases. This object was found by David Todd in 1878 in an early search for a trans- Neptunian planet. He was looking for compact objects that revealed possible motion across the sky and of course he was unsuccessful in this attempt. But he did run across a couple of dozen new galaxies. He often gave poor positions for his discoveries (and so they were subsequently "lost" by cataloguers), but fortunately, he made small eyepiece sketches of the field and this has allowed the NGC/IC Project to track down all of his discoveries. NGC 3217 (the 29th "candidate" found by Todd) was later rediscovered by a Javelle, a french astronomer, and is generally known as IC 606. I can see why Todd paused on this object. In my 18-inch it was just a faint glow, perhaps 0.4'x0.3' in size with just a weak concentration and could mimic a dim planet.

So, it ended up a very enjoyable night for the Matts and I. Thanks for meeting up on a Sunday night! After midnight I was worried about turning into a pumpkin as I had a class to teach in the morning, so I rushed home to nap for a few hours and to dream of starry nights.