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Thursday, January 6, 2005

Comet Machholz Approaches the Pleiades

When I arrived back in Switzerland early on the morning of Tuesday, 4th January 2005, the temperature was -4°C and the sky was that perfect dead-of-winter clear which invites amateur astronomers to venture into the dark regardless of the mercury or risk of losing the odd extremity to frostbite.

After hauling everything inside, I immediately hauled myself and the binoculars outside and quickly spotted Comet Machholz (C/2004 Q2), which I hadn't seen since December 26th. After locating the comet with binoculars, I found it a relatively easy object for the unaided eye, but that's an amateur astronomer with 40+ years of experience seeking faint smudges in the sky speaking. While the comet was easy to spot without averted vision, you had to know where to look and what to expect--this is no Hale-Bopp.

Having spotted the comet, I tried to photograph it with the Nikon D70 and 28-200mm zoom lens I use for general photography with this camera. The dimness of the comet was a serious challenge--even with the CCD sensitivity set to the equivalent of ISO 1600 (at the expense of sensor noise), a 10 second exposure at the maximum aperture of f/3.5 and shortest focal length of 28mm (equivalent to a 42mm moderate wide angle on a 35mm camera), about the longest which doesn't generate obvious star trails due to the pesky rotation of the Earth, only subtly showed the fuzzy coma which identified the object as a comet.

This image is the pick of the litter. It approximates the visual appearance of the comet, and the field of view of the unaided eye. Actually, the comet is less obvious but, once spotted, appears more extended than the compact fuzz-ball shown here. The peak of the roof of the house at left and the house at the right are illuminated by Fourmilab's Christmas lights.

Since I took this picture, nights have reverted to the usual fog, clouds, and precipitation, so I haven't had a chance to try other imaging options. If the sky is clear for the passage by the Pleiades on January 7-8, I may try imaging it with the SBIG ST-6 cooled CCD camera I used for comets Hyakutake and Hale-Bopp.

Posted at January 6, 2005 01:16