Some Sonoita Astronomy

by Mike J. Shade


What a difference a day makes! Since Sunday March 7 was cloudy and windy, the clear sky and cool temperature of Monday the 8th was a welcome change. Since my G-11 mount bit the dust, local Sonoita astronomer Jay LeBlanc invited me over to use his 17.5" Mel Bartles modified Dobsonian. Jay is completing a visual survey and compiling a database of his observations. On this occasion I was sort of "riding along" as he went through his list. I did coax him into looking ot a few of the brighter and well-known objects.

A few words about Sonoita Arizona. This town is located about 40-45 miles S/SE of Tucson, 25 miles W of Sierra Vista and 25 miles NE of Nogales. As a results there are three light domes visible: Tucson's extending perhaps 15-20 degrees high and 20 degrees wide, Sierra Vista's extending perhaps 15 X10 and Nogales similar to Sierra Vista's. Sonoita is at about 5000 feet elevation and is rolling grasslands. As a result of the scarcity of trees, lights are visible quite some distance away. However, most people are in bed by 9:00 and most lights are off by then. Although not the perfect location, it is pretty nice.

The evening started with fair transparency, 6 on a 1-10 scale and good seeing. 7 on a 1-10 scale. Stars in Orion were not twinkling much if at all. The first object, NGC 2522 a mag 13 galaxy seemed a tight spiral, elongated with suspicious fuzzy regions. The transition between the center and arms was very soft and subtle (9mm Nagler, 221X). It reminded me of M31 naked eye. NGC 2340 at magnitude 14.24 was a slightly oval smudge with a dim star off of the major axis. There was an interesting contrast between the star and the galaxy. Of course we peeked at M65, 66, 95, and 96. However, NGC 3628 showed its dark lane easily with averted vision and the upper section was much brighter. At 170X the dust lane had several knots in it, with several dark "caves" visible within the lane itself. Next, the Abel cluster 1142 (?) showed 4 or perhaps five little shimmering softly glowing galaxies. NGC 3506 showed a small round glow of even brightness well UGC6112 at magnitude 15.27 was a tough object, visible with averted vision only. NGC 3524 was a small galaxy but bright for its size. We wrapped up with M108, an oval object, the west portion being dimmer but with more spots but the east section was brighter with less spots (E/W of center condensation).

By this time some high clouds had drifted in so it was time to call it a night. Not at all bad for observing from Jay's front yard.