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Reports from Geisei Observatory <November 15, 2007>


Comet Holmes changes in color and size

    In late October I observed Comet Holmes through the 20cm refractor. It was brightening and showed a beautiful golden-yellow coma. The central condensation was glowing as white as snow and a perfectly stellar nucleus was vividly seen near the middle of the condensation. The 20'-wide coma was enveloped by very faint, extensive purplish gas. Photos by the 60cm reflector also showed a vivid golden color.
    About two weeks later the comet was brighter and its coma grew to nearly 30' in diameter, almost as large as a full moon. The colors of the coma changed, too, perhaps due to temperature changes during the brightening, from gold to bright blue. Visually it looks white but greenish blue in photographs resembling a traffic light. These changes have occurred over a short period of about 10 days. In the next diary entry I will describe the appearance of the comet which has began showing a tail.

17P/Holmes
5-minute exposure from 20:00, October 29, 2007
60cm f/3.5 reflector, ISO 800 film



17P/Holmes
5-minute exposure from 2:00, November 11, 2007
60cm f/3.5 reflector, ISO 800 film



Copyright (C) 2007 Tsutomu Seki.