Time: 01:30 U.T.
Binoculars: 8x42
Seeing: Good
NELM: Approximately 6.0
Temperature: +17 F (-8 C)
Comet McNaught's tail was observed above my west-southwest horizon near the end of astronomical twilight. My sky was compromised a little with smoke from a not too distant fire. The thin haze from the smoke could be seen in all directions prior to darkness. I had to walk over some semi-rough terrain to get to my 'good' western horizon. From my regular observing locations nearby trees compromise that horizon.
The sketch was made immediately upon returning indoors. I tried to memorize enough of the star patterns to accurately place the rays from the comet's tail. The known eight degree field of view of the binoculars was used as an aid in making angular measurements. The longest (right most) ray was approximately sixteen degrees in length. Its top extended beyond the top of the dark cloud. The upper ends of the other rays were obscured by the cloud, the bottom of which was about nine degrees above my horizon. The span between the outermost rays was estimated to be about ten degrees at the horizon. Venus (not shown) is just below the horizon about three degrees to the left of the left most ray. Lines have been drawn connecting some of the stars into familiar constellation patterns.
Four primary rays were seen. In addition to the two outermost rays, there was a center pair of rays. Hints of additional rays were seen with increasing frequency to the right of the second ray from the left. The rays were visible with difficulty to the unaided eye. They were much better with the 8x42 binoculars. The approximate azimuth of the center of the ray system along the horizon was estimated as 252 degrees.
At the time of the observation the Sun was approximately seventeen degrees below the horizon directly below the bottom end of the rightmost ray. The comet was approximately twenty-three degrees below the horizon at an azimuth between the left edge of the sketch and the left most ray.
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