September 15, 2010

CHASE FOR COMET 103P HARTLEY


An icy visitor is positioning itself for easier viewing in the coming weeks. it will be high in the evening sky when at its best, glowing at perhaps 5th magnitude. It should be dimly visible to the unaided eye from very dark locations, and visible in binoculars and telescopes. On October 20th, the comet will be just 0.12 A.U. from Earth. The comet has reached 9th magnitude and is brightening by 0.1 magnitude per day. So right now, before the Moon washes the sky with light, is an especially good time to look for this faint visitor.

As shown in the chart, on the night of Sept 15, the comet is in Andromeda, some 4.5 degrees N-NE of Omicron Andromeda star. On Sept 20th the comet will be just about a half degree from an open cluster NGC 7686. On October 1st the comet will be just 1 deg. 37’ from Alpha Cassiopeia. Perhaps 6th magnitude by then, it should remain at least this bright for the next nine weeks. But it's important to note that, with the comet now just 0.18 a.u. from Earth and closing, its light is no longer concentrated into a small dot but instead is more spread out. So even if you can sight a 6th-magnitude star with the unaided eye, Hartley 2 will be tougher. It's closest to Earth on October 20th at a distance of just 0.121 A.U.

On the night of October 7th the comet will be just 1.5 degrees away from beautiful “double clusters”. This will create great opportunity for astro-photographers and sky observers. On October 18th the comet will pass within 3 degrees south of brilliant Capella. On October 27th after midnight the comet will pass within 4 degrees E-NE of a rich open cluster M35 in Gemini.

-Rahul Zota (Bhuj-INDIA)

1 comment:

Keerthi said...

Thanks for the post Rahul. I hope the weather clears up and allows us to see this comet...