ISON Image of the Week

It's Alive! (Aug 19, 2013)



While certainly not the most spectacular view of C/2012 S1 (ISON) that you will ever see, this image from Austrian astrophotographer Michael Jäger was recorded under difficult observing conditions, as ISON still sits low to the horizon.
After several weeks of being hidden behind the Sun, comet C/2012 S1 (ISON) is finally beginning to re-emerge, and early, tentative measures of its brightness hint that it is indeed beginning to slowly brighten up -- which is what we hoped and expected it would do!

From the ground, we last saw Comet ISON in June of this year, and at the time there was much concern that it had brightened only marginally since January. So when we lost sight of it behind the Sun, speculation began to circulate that maybe ISON really was a dud. Indeed some rather alarmist reports even claimed that the comet had already fizzled! (Matthew and Karl from the CIOC felt compelled to step in and quash that rumor with a dose of reality.) So as the weeks pressed on through July and into August, we waited impatiently for the comet to reappear from behind the Sun, holding our breath and wondering when the first observers would capture it.

When that ground-based detection finally came, it was not from a well-known cometary astronomer using a large and powerful telescope, but an amateur astronomer, Bruce Gary, who was inspired by a challenge from his local astronomy club to try and recover the comet! Under extremely difficult observing conditions, it was a remarkable achievement!

Within a few days, other observers around the world began to image the comet in the twilight skies, with one of the earliest detections in Europe coming from the prolific comet astrophotographer Michael Jäger (Austria), who was able to capture images of Comet ISON on consecutive mornings. The image we are featuring here was taken by Michael on August 18 and, as Michael notes, shows Comet ISON sporting "a 2' tail and no outer coma". The lack of a visible outer coma isn't of great concern here; the twilight viewing conditions are still quite difficult, and the comet is only just now beginning to "switch on" and its water-ice starting to sublimate (melt).

What is encouraging is that in the few weeks since we last saw it, Comet ISON has indeed started to brighten up at least somewhat, with reported visual magnitudes around m13. It is still too early to use these values to predict how bright the comet will ultimately be (or indeed if it will even survive!), but we can at least dispel the false rumors of its demise. Over the coming weeks, the comet will move into darker skies and as astronomers report their data to the MPC, we will be able to get a better picture of its current behavior and possible future outcomes. Right now there are conflicting reports on different popular astronomy websites, with some saying the comet is clearly under-performing, while others claim it's right on track. We think it's a little too early to make that call, but we will certainly comment on that when the time comes.

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!