Comet ISON, the predicted super comet of 2013, has now brightened to 10th magnitude and within the range of medium aperture telescopes. When discovered at the end of last year, the hype surrounding this possible "comet of the century" went into overdrive. It was predicted to reach an incredible magnitude -16, visible in daylight and be brighter than the full Moon, when close to perihelion in late November 2013.

At perihelion ISON will be only 0.01249 AU (1.87 million kilometres or 1.16 million miles) from the Sun. At such a small distance, there's a real possibility it might not even survive the hostile environment, disintegrating before reaching the other side.

What was also over looked in the popular press last year was that peak brightness occurs for just a few hours during daytime. And of course an object at magnitude -16, right next to our star, appears nowhere near as bright as might be expected. But anyway, it's still an exciting prospect and a potentially great spectacle over the next couple of months.

Recent estimates now suggest that the ISON will peak at about magnitude -7 or -8. On October 11th, the comet stood at magnitude +10.6 with an elongated coma, visible in 250mm (10-inch) or 200mm (8-inch) telescopes in the morning skies just before sunrise. Visually detecting a tail was more difficult. However, the comet and tail could be imaged with much smaller scopes.

ISON is expected to reach naked eye brightness about the middle of November and remain so until the end of December. During this time the best location to be is the Northern Hemisphere. It will be observable in the early morning sky towards the east throughout the brightening period. From the Southern Hemisphere, the condition is not so great with the comet remaining low down during this time.

The finder chart below shows the path of ISON from October 9th to October 29th as it moves through Leo. Also in Leo during this time in Mars and ISON will move eastwards towards Mars before overtaking it. On October 15th, ISON (mag. +10.2) will be about a degree north of Mars (mag. +1.5) and two degrees north of Regulus (α Leo - mag. +1.4). The latter two are about the same brightness and easily visible to the naked eye but the comet is much fainter (3000x) and probably requires at least a 100mm (4-inch) telescope to be seen; preferably a larger scope. Mars and Regulus do act as good pointers to locate ISON.

Comet ISON Finder Chart from October 9 to October 29, 2013 - pdf format

On October 25th, ISON is predicted to be at magnitude +9.2 and located 1.5 degrees south of three 10th magnitude Messier galaxies, M95, M96 and M105. The comet is a magnitude brighter than the galaxies but may appear similar in appearance, size and shape.

ISON remains in Leo for the remainder of October before moving into Virgo next month when the real fun begins!!

Comet ISON (C/2012 S1) Data (at epoch February 28. 2013)

Comet ISON (C/2012 S1) Data Table