Image: Comet ISON shows a small, compact coma and short, faint tail in this photo made by Hungarian astrophotographer Krisztian Sarneczky on Aug. 31, 2013. Credit: K. Sárneczky / Konkoly Observatory
The latest brightness estimates from the amateur comet community place ISON around magnitude 13, bright enough to be within reach of 10-inch (25 cm) and larger telescopes. Alan Hale of Arizona, co-discover of Comet Hale-Bopp, was one of the first to see it. Through his 16-inch (41 cm) reflecting telescope on September 1, he noted the comet as a small object about 0.6 arc minutes across (1 arc minute = 1/30 the diameter of the full moon), brighter in the center and shining faintly at magnitude 13.1. Picture a small, dim patch of glowing mist and you’ve got the picture. Hale’s observing conditions were excellent though he did have to contend with light from the nearby crescent moon. Starting tomorrow morning, the moon will finally be out of the picture.
While it now rises around 3-3:30 a.m. local time, you’ll get your best – or only – view once ISON has cleared the light-sucking thick air and haze so common near the horizon. The optimum viewing time occurs shortly before the start of morning twilight when the comet will be about 15 degrees high in the northeastern sky. At mid-northern latitudes,where twilight begins about 1.5 hours before sunrise, that’s around 5 a.m. Did I mention you’d lose a few hours sleep in your pursuit?
Lucky for us comet hunters, ISON’s location is easy to find only a few degrees east of the 1st magnitude planet Mars and about 2 degrees north of the familiar Beehive Cluster or M44. The first map shows the general view to get you oriented. The second takes us in closer to show the comet’s relation to the Beehive Cluster, and the third provides a detailed telescopic view with stars plotted to about 12th magnitude