Observing report for 31 March 1997




Comet Hale-Bopp


After some afternoon cirrus, the skies had cleared off by dark. I had to work the Physics help session from 6-8pm, where 8pm is the end of local astronomical twilight. Thus, I ran out of the building to my car, drove home, changed into my boots, grabbed my waiting equipment and managed to leave home at 8:10pm! The drive to my observing site takes about 12-14 minutes, and I was hoping to be photographing the comet by 8:30pm (3:30UT). The drive went well, and I hurriedly set up and polar aligned. My first exposure started at 3:29UT! The night was clear, with a single narrow thin cloud visible in front of the bright zodiacal light. The temperature was falling through the 30s, and the wind, which had been as high as 25 mph during the afternoon had died down to nearly a dead calm.

I photographed for about 30 minutes, and then settled in to actually observe the comet for a while. The naked-eye limiting magnitude was it's usual high 6's near Polaris. By this time the head of the comet was only about 10 degrees above the horizon. With 7x50s, I could see an obvious bright streamer in the first 6 degrees or so of the plasma tail on the right-hand edge of tail with an obvious dark lane separating this streamer from the rest of the plasma tail. Any other detail in the tail was weak; the two previous nights I noticed more detail, but the primary streamer wasn't noticably brighter than the rest of the tail. I have undeveloped film from the last three nights and I can't wait to see the night-to-night changes that should be visible!

The naked-eye tail lengths were 16 degrees for the plasma tail (almost to Epsilon Cas, but with interference from the Milky Way), and 15 degrees for the dust tail (to about Alpha Cas). Only the first 6 degrees of the dust tail was bright.

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