getting to know Corvus (Union)

It was interesting this evening to get a chance to view some objects very low in the south. Huh. If there wasn't the hill off Mom's back yard, we might be able to see bits of Centaurus. In fact, at one point, I thought I had seen a star that belonged to that constellation. But it turned out I was misreading, in the dark, the chart. The constellation boundary lines in Pocket Sky Atlas are a bit difficult to make out in dim red light. Still, spotting γ (gamma) Hydrae, in the tail of the snake, was fun. Looks like it was about 18° up in elevation.

Shortly before 1:06 AM, I prepared to locate a double star in Corvus. Geese were nattering away off in the east somewhere. Coyotes yipped to the north. I found the finder scope on my Celestron SCT dewed up! The Oregon Scientific weather station reported 63% humidity and -0.4°C. My custom dew heaters were still installed but they are broken and I've not gotten around to fixing them yet. So I took the 8" heater from the corrector plate, after covering the open end of the dew shield with the cap, and I wrapped it length-wise around the finder scope. I left it try for about 5 minutes. That worked nicely.

δ (delta) Corvi, aka Algorab was easy to find. It is a pleasing double, easily separated at low power. The main star is bright, but the other is faint. I took a wild guess at the separation being a bit less than 30 arc-seconds (Haas, from her book double stars, says they are 24.9" apart). The main star looked yellow-white while the companion was a challenge to put a colour to. Perhaps pale blue. Hey! I remembered to guesstimate the Position Angle and remembered to use the correct orientation through my SCT with mirror diagonal, i.e. clockwise. I estimated the PA to be 220 degrees (Haas says 217°).

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Once again, I learned, after the fact, that I have already looked at this double star!

But this has highlighted an error. I had recorded the wrong short form for the constellation name upon my first observation. My old entry shows as "Cor" when it should be "Crv."

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As the evening wore on, despite the improvement in altitude, I could not see Crater clearly. Only δ Crateris stood out.