Steady seeing conditions at Bumpass!

by Steve Gottlieb

A couple of folks have commented on the excellent seeing at the Bumpass Hell lot. Thursday night we had clouds creep up from the south until only the northern sky was completely clear. A number of folks packed up somewhat early but I continued observing galaxies in Draco and was enjoying the pinpoint stars at 325x-450x. After 2:00 AM, I started looking at close double stars as clouds had covered much of the sky.

First up I took a look at Struve 2438 in Draco (period of 230 years) at 18 57.5 +58 13, an 0.8" pair of mag 7 stars that were cleanly resolved at 565x without a problem. Next up was Lambda Cygni (period of 390 years), an 0.9" pair, but with the components having a large magnitude difference (4.6 and 6.2) this one was a bit trickier. In any case, I recorded "easily resolved at 565x with two hard airy discs cleanly separated by dark space."

Finally, I took a look at the binary pair Otto Struve 387(period of 155 years) at 19 48.7 +35 19 . This is an 0.6" pair of mag 6.9/7.9 stars and again were cleanly resolved at 565x. Unfortunately, I didn't have a list that included closer pairs but I feel certain I could have gone down to 0.4" on an equally bright pair. So, yes the seeing was clearly sub-arc-second!

Steve

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