Comet 17P/Holmes 25 October 2007 The full moon was close by and the jet stream was right over Nova Scotia so the seeing was very bad. In this 25 second exposure the comet has a well defined nucleus and a huge coma. Equinox 6 calculates that 17P is 244 MKm from earth. The Equinox Image astrometry function calculated the coma extends for 2.34 arcminutes. That makes the coma over 166,000 km in diameter. That is bigger than Jupiter! Equinox 6 calculates that 17P should be about magnitude 13 but this outburst has increased the magnitude to 2.8.

5 5-second exposures, imaged, aligned, stacked, LRGB in Equinox Image. Stars superimposed from 30 second image.

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