Thursday, October 17, 2013
Comet C/2012 S1 ISON meets Mars, 16-23 October 2013
Rumors of Comet C/2012 S1 ISON's demise are greatly exagerated. It is still brightening and looking very nice. Currently it is visible in modest amateur instruments such as 10-12" reflecting telescopes. Currently magnitude 10, It should theoretically be visible in smaller scopes, but its fuzzy, diffuse nature and its closeness to the horizon (between 7 -12 degrees depending on where you are, except Darwin and Far North Queensland, where it is more like 20 degrees above the horizon) means that it is difficult to spot visually in smaller scopes.
The highlight of this week is the comets close encounter with Mars. Comet ISON was actually closest to Mars on October 1, but the orbital geometry means that from Earth it will appear closest on the 18th. Between now and the 23rd though Mars and ISON (and the nearby bright star Regulus) are still close enough for good imaging opportunities (although you can't see it visually, long exposures on varuous imaging systems will bring it out). The comet is just below and to the left of Mars, making finding it relatively easy. Over the next few days it is roughly midway between the brightish star 37 Leo and Mars, making it even easier to find.
There have been some great images taken so far of ISON and Mars and Regulus, some with just DSLR's (at really high ISO ratings though). Here's another using a telephoto lens. So it's well worth having a go at imaging it under dark skies (the waxing Moon may be a problem though). Some charts that allow you to find the comet more easily. A printable PDF version is here.