Thursday, November 14, 2013
Comet C/2012 S1 ISON fires up! 15-22 November 2013
Comet C/2012 S1 ISON has turned on. Gianluca Masi has seeing it naked eye using averting vision from a good dark site. The TRAPPIST team have reported a doubling of gas production in the last 24 hours, and creditable reports put the comet between magnitudes 6.5 and 6.1. This represents around a full magnitude jump in 24 hours.
What this means for the comets future is uncertain, this may be a prelude to a more steady brightening, as the comet is well inside Venus's orbit, or it may be the prelude to disintegration. Only time will tell but now is a good time for observation.
Still, unless there is significant brightening in the next few days it will still be difficult to see from Australian sites. Visible in 10x50 binoculars it has been described as having a star like appearance. However, its fuzzy, diffuse nature, its closeness to the horizon (between 2 -8 degrees depending on where you are, except Darwin and Far North Queensland, where it is more like 16 degrees above the horizon see here for charts illustrating the difference at different sites) means that it can be difficult to spot visually in binoculars and smaller scopes.
The comet is to the right of Mars, and heading for the bright star Spica. Making finding it relatively easy on a line between Spica and Mars. The best time to look for it is when it is highest in the sky and the sky is darkest. However, especially in the Southern States, because it never gets very high, the best time to look is astronomical twilight. Astronomical twilight is an hour and a half before local sunrise.
On the 15th comet ISON is a handspan above and to the right of the bright star Porrima, and should be (just) visible to the unaided eye and easily visible in binoculars. However, the comet is also sinking towards the horizon, so you will have to wait deeper in the twilight for the comet to get reasonably high above the horizon, as the sky brightens the comet will be more difficult to see, offsetting its own rise in brightness.
The comet is also moving very quickly now, as it begins its final dive into the sun. Over the next 4 days the comet quickly approaches the bright star Spica, the obvious and brightest star in the constellation of Virgo. Comet ISON is closest on the 18th and 19th and should be very easy to pick up with this obvious guide post.
After this there are no obvious bright stars to act as guide posts, hopefully the comet should be fairly obvious. Whether it will outpace the rising dawn, and be come easily visible to the unaided eye without binoculars is uncertain at this stage. The comet is sufficiently low that you need to start looking at nautical twilight, and hour before local sunrise.
A printable PDF map is here.
Venus is going off precisely at 7.45 pm till it sets.
But I'm pretty sure I saw SION from Canberra this morning at 4.40am due East with unaided eye but it's very faint(and I was standing in a Trig point Triangle).But did anybody notice the other strange stuff?. I won't go into detail or be awarded the Tin Hat award, and was looking straight out over ADFA ;)
Comet Lovejoy is near Osiris-Orion too.