ISON Image of the Week

A Comet's Tail  (Sep 16, 2013)



This 60-second exposure of Comet C/2012 S1 (ISON) was recorded on September 14, 2013, by Gary Fildes at Kielder Observatory, England. Gary estimates ISON to be around magnitude 12.2 in this image.
Bit by bit, day by day, comet C/2012 S1 (ISON) continues to make steady progress en route towards its toasty encounter with the Sun on November 28, 2013. Last week we posted a beautiful star-filled scene containing M44, Mars and a just-barely-visible Comet ISON. This week, there's certainly no need to squint your eyes to see our favorite sungrazing comet!

This image of Comet ISON was captured at the Kielder Observatory, situated in the north of England just half a mile from the border with Scotland. The site is recognized as one of the darkest in the UK, and affords the small team of dedicated Observatory volunteers some beautiful views of the night sky. When this image was recorded on September 12, 2013, amateur astronomer Gary Fildes was at the helm of their 16-inch telescope.

"Conditions were OK after a front had passed through", Gary said in an email to the CIOC, allowing him to take this 60-second exposure of the comet in a 10'x10' field of view. "It was a late capture as the comet tracks through Cancer. Seeing was not brilliant, maybe +1" or slightly more, so focus is a problem."

He estimates its brightness as magnitude 12.2 - a value that is right in-line with the brightness currently being reported by other amateur astronomers around the world.

One important thing we can tell from images like this is that ISON is beginning to develop quite nicely, just as we expect it to! In particular, its coma and tail are becoming more pronounced -- the latter in particular -- as its surface ices are melting away at ever-increasing rates. With only 74 days to go until perihelion (closest approach to the Sun), we can be encouraged that the comet's brightness is continuing to climb and, as yet, Comet ISON gives no indication of fizzling out! Of course that could still happen at any time, but we in the CIOC have always felt quite confident that ISON will at least make it to perihelion, and we still see no reason to back off of that prediction.

Once ISON reaches perihelion, all bets are off! It will be bombarded by solar radiation that will vaporize enormous volumes of its surface ices as it passes through the millions of degrees solar corona, and will be stretched and pulled to near - or beyond - breaking point by the Sun's extraordinary gravitational pull. But traveling at over 300km/s can have its advantages, and for ISON the advantage will be that it only has to experience that most extreme of environments for a few hours at most before it can head back out into deep freeze!

Will Comet ISON make it, or will it succumb to gravity and radiation? We truly have no idea, but what we can do is enjoy it while we have it, learn as much as we possibly can, appreciate great images like the one featured here from Gary at the Kielder Observatory, and hope that the comet's best is still to come!

Every week this year we will put up a new image related to Comet C/2012 S1 (ISON). If you have a cool image you'd like us to consider, please send it to sungrazer@nrl.navy.mil, along with a description and any credits you would want applied. We'll contact you if we choose to use your image on the CIOC Website.

See our ISON Image of the Week Archives for earlier picks!