Friday, January 11, 2013
Comet C/2012 F6 Lemmon Passes Through the Heart of the Southern Cross
Comet C/2012 F6 Lemmon is quite bright at the moment, being much brighter than predicted.
It is currently magnitude 8 and will brighten over the remaining month to around magnitude 6.5. At magnitude 8 the comet will be tricky to observe in 10x50 or smaller binoculars under light polluted suburban skies. But as the weeks go on it will become quite easy to see in binoculars as it brightens.
It is a reasonably easy target with a small telescope under most skies. Unfortunately, towards the end of the month the waxing Moon will make observing more difficult (Full Moon 27 January).
In February it will brighten up to magnitude 3, easily observable with the unaided eye.
The comet is well placed for observation from around midnight, but the comet is highest early in the morning. It is in a rich area of the sky, and from the 16th the comet is within binocular distance many open clusters. Between the 18th and the 22nd the comet crosses the iconic constellation of Southern Cross and the star clusters that lie at the heart of this constellation.
Many of these are quite dim, and not observable in binoculars, but reasonably easy in even small telescopes. The brighter encounters are listed below (magnitudes in brackets).
On the 20th it the comet close to the open clusters NGC 4755 (4.2, the iconic Jewel Box Cluster) and NGC 4349 (7.4). On the 21st it's near another open cluster, NGC 4609 (6.9). On the 22nd two more open clusters are nearby, NGC 4463 (7.2) and NGC 4815 (8.6, a bit too dim for binoculars).
On the 26th, after it has the comet is close to the globular cluster NGC 4833 (7.4) and on the 27th the globular NGC 4372 (7.8).
Locating the comet is reasonably easy with 10x50 binoculars, from the 11th to the 16th, sweep down along the axis of the Southern Cross, looking for a fuzzy star. At the moment the tail is small and dim. You may need to watch over a couple of nights to see it move and make sure it is not a star cluster. From the 18th to 22nd the brightening comet should be easy to observe in the heart of the Cross.
In the later part of the month, when the Moon has set, even simple digital cameras with a timer function should be able to image the comet with 15 seconds or more exposure time (you will need a tripod).
While not spectacular, this will be a good comet, and a good opening act for the potentially spectacular comet 2011 L4 PANSTARRS in late February.