New Comet Machholz

Don Machholz of Colfax, CA, has spotted an 11th-magnitude comet low in the morning sky in the constellation Pegasus. He was using his 18-inch Dobsonian reflector at 77x. In reporting the find to the Central Bureau for Astronomical Telegrams (CBAT), Machholz described the comet as having a 2' coma and no tail. But when he first caught sight of it on March 23rd, twilight was coming on so fast that he could not tell which way it was moving. After an agonizing three days, he again located it, still in Pegasus but now 6° farther east.

Late last night CBAT announced the discovery on IAU Circular 9132, which includes confirming observations by Japanese amateurs Y. Ikari, K. Kadota, and K. Yoshimoto.

This is Machholz's 11th comet discovery, his others being made from 1978 to 2004. Like all his others, this was a visual find — something unusual in this age of CCD-equipped backyard telescopes, automated professional surveys, and spacecraft also vying for comets.

Preliminary Orbit

Brian G. Marsden of the Minor Planet Center issued Minor Planet Electronic Circular 2010-F88 today, giving preliminary orbital elements for Comet Machholz. These show the comet already well inside Earth's orbit and approaching perihelion on April 5th, but also receding from Earth. So its brightness will stay practically constant for the next two weeks. Its elongation from the Sun is also diminishing, so it will probably be lost in the Sun's glare after mid-April. The following table will help in finding it before then.

Comet Machholz, C/2010 F4
h   m
°   '
Mar. 2823 37.2+32 2212.0Peg
Mar. 2923 46.6+32 2412.0Peg
Mar. 3023 55.8+32 2312.0And
Mar. 3100 04.9+32 1912.0And
Apr. 100 13.7+32 1112.0And
Apr. 200 22.3+32 0012.0And
Apr. 300 30.7+31 4612.0And
Apr. 400 38.8+31 2912.0And
Apr. 500 46.6+31 1012.0And
Apr. 600 54.3+30 4812.1Psc
Apr. 701 01.6+30 2512.1Psc
Apr. 801 08.7+29 5912.1Psc
Apr. 901 15.6+29 3212.2Psc
Apr. 1001 22.2+29 0412.2Psc
Apr. 1101 28.6+28 3412.3Psc
Apr. 1201 34.8+28 0412.3Psc

Stay tuned to our website's observing highlights. Good luck, and clear skies!

Roger W. Sinnott
Senior Contributing Editor
Sky & Telescope

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