The Night Sky: Comet ISON

Attached is a picture I took of Comet ISON on 2013-11-13 at 5:15AM. It was taken at June Hill Observatory using a TV101is refractor and Canon 60Da camera. Eight one minute exposures were stacked in Deep Sky Stacker software using comet mode. The resulting stack was processed in Photoshop CS5. Because the comet moved relative to the stars during data acquisition, and since the stack was aligned on the comet, the stars trail out into lines in the image. This gives the impression that the comet is quickly streaking through the sky, but that not the case.

I had interference from a tree and had to wait until the comet cleared most of the branches. Some dark patches from blurred branches can be seen at lower left in the image. Sadly, by the time the comet cleared the branches twilight had begun. The brightening sky reduced contrast in the tail. 

Comet ISON is much dimmer than predicted to be at this time. It has brightened considerably since this picture was taken as is plunges closer toward the Sun and volatiles sublimate off its surface. It was hoped ISON would be visible in the east at dawn to the naked eye and have a huge tail, but that hasn’t happened. It will pass less than on solar diameter from the Sun on November 28th, and as such it is considered a ‘Sun grazer’. If it survives that close approach it may still be spectacular in the dawn sky in December. 

Comets are simply unpredictable. ISON can still impress or just break up into pieces and fizzle out as it nears the Sun. I’ll keep observing its progress and will keep you posted.