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Thursday, November 1, 2007

Astronomy: Comet 17P/Holmes Spotted, Photographed from Fourmilab

From the time of the October 24th outburst which caused Comet 17P/Holmes to brighten more than a millionfold—from 17th magnitude to naked-eye magnitude 2.5, the skies above Fourmilab were uniformly opaque until the night of October 30th, when I was able to briefly glimpse the comet with binoculars through a gap in the clouds which closed before I was able to set up a camera. The next day was overcast and foggy well into the night, when falling temperatures cleared the sky sufficiently to see the comet with the unaided eye. The sky was still a little milky, but this object is sufficiently bright that it punched right through.

Here are two pictures, both taken with a Nikon D200 digital SLR and 18–200 mm zoom lens, at ISO 1600 sensitivity. The first was taken at 18 mm and shows the position of the comet in the constellation of Perseus.


Next is a close-up, taken at 70 mm focal length, which shows the fuzzy coma of the comet. The geometry of the comet, Sun, and Earth is such that the tail, if one is forming, is pointed almost directly away from us. This may account both for the unusual appearance of the comet and its brightness. Here is a chart, generated by Solar System Live which shows the comet's location in its orbit.


You can display a chart of the position of Comet Holmes in Perseus at the time these photos were taken, courtesy of Your Sky:

Posted at November 1, 2007 02:51