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Posted by Nick James at 19:00 on 2013 Nov 26
There are conflicting reports but building evidence that the Comet of the Century has disintegrated prior to perihelion. Observations in mm waves appear to indicate that the production rate of volatiles has dropped dramatically and the comet is not brightening as expected in the STEREO spacecraft images. The implications of these observations is that the comet is now nothing more than an expanding cloud of dust that will not survive perihelion. This is still to be confirmed but my earlier optimism as expressed at last Saturday’s BAA meeting is now somewhat diminished. The comet should shortly appear in the SOHO LASCO C3 instrument so we should know more then.Nick.
Posted by Denis Buczynski at 22:18 on 2013 Nov 26
This comet can best be described as a roller coaster comet, it has been on the up and now (maybe )on the down. However it has continued to confound many predictions and it may yet do so again. There seems to be conflicting evidence abou the current situation. Both NASA and CIOC are still optomistic about the comet surviving perihelion passage. The first images from the SOHO spacecraft will tell us more. If there is a total disintegration of the comet,then we may have a superb post perihelion dust tail display like one seen with C/2011 W3 Lovejoy and we could see an headless wonder type comeet. With two days to got to perihelion all scenarios are still possible. The game may be getting towards the final whistle but sometimes the extra time can be the most exciting part of the event. This is why comets are a fascinating objects to follow, one never knows how matters can turn out. As usual the best advice is to watch that space, in what ever way you can.Denis Buczynski
Posted by Callum Potter at 09:19 on 2013 Nov 27
Well seems to be visible on todays SOHO LASCO C3 images. Not sure how to infer how bright though…http://sohowww.nascom.nasa.gov/data/realtime/c3/512/Callum
Posted by James Fraser at 16:13 on 2013 Nov 27
Now as bright as Antares according to a CIOC_ISON group on Facebook.
Posted by Nick James at 23:19 on 2013 Nov 27
James,Indeed, as Denis says, this comet’s performance has certainly been on a rollercoaster recently.The latest LASCO C3 image shows a significant blooming spike which implies that the comet is probably negative mag now. It will be interesting to see how it evolves through perihelion and we can watch how events unfold almost in real time using the SOHO cameras.Nick.
Posted by James Fraser at 10:51 on 2013 Nov 28
Nick,Yes, a great description of events by Denis.Much excitement on the internet now with reports of magnitude -3Today should be very interesting as events unfold.James
Posted by Nick James at 18:21 on 2013 Nov 28
Like Monty Python’s parrot I think the only reason that this comet is still sitting on its perch is that it has been nailed there. It is now visible in the SOHO LASCO C2 field and there is no saturation blooming. Reports indicate that the nucleus no longer exists and we are just seeing a cloud of dust and debris.I’d love to be wrong though. Watching it on the SOHO images is fascinating, although quite hard at times since the site is clearly overloaded.
Posted by Grant Privett at 00:07 on 2013 Nov 29
Will be interesting to see if, in a week or three, imagers can find anything near the predicted position.
Posted by Denis Buczynski at 13:10 on 2013 Nov 29
C/2012 S1 ISON will no doubt be remembered as one of the most unpredictable of comets. During the perhelion passage yesterday the first impressions were, as we watched via the SOHO spaceraft images, that the comet had totally disrupted and that there would be no coherent part of the comet’s nucleus left intact. The comet would be dead. However as time progressed we began to see a small but quite bright section of the tail reappear from behind the instrument’s occulting disc. Then this bright tail section seemed to become more compact and a short new tail seemed to start to reform. So it seems that a least a small part of the nucleus survived and has now begun to form a coma and shows some signs of emmisions taking place. Whether this means that the comet will continue to survive and be able to be seen in our skies in the next few weeks is still very uncertain. There may not be sufficient material left and the comet could fade away. However the posibilty of the comet remaining active and being observable,in some form,in the morning sky during the next few weeks is significant. This comet may yet suprise us again, we can only watch in amazment and some awe to observe what nature will offer us.If the nucleus does survive and remains coherent, there is one thing that is certain, it is a long way back to the Oort cloud from here!Denis Buczynski
Posted by James Fraser at 23:56 on 2013 Nov 29
In the words of a famous song..She comes out of the sun in a silk dress runningLike a watercolor in the rainDon’t bother asking for explanationsShe’ll just tell you that she cameIn the year of the cat(Al Stewart – Year of the cat)
Posted by Neil Morrison at 16:13 on 2013 Nov 30
The Latest Lasco image 14.42 30th nov appears to show Ison vanishing like the proverbial Cheshire Cat. Will the smile remain long enough for us to see it in the early December Dawn!!
Posted by TonyAngel at 20:53 on 2013 Dec 02
I tried this morning but the sky was too bright. I will be trying each morning this week – subject to weather – just to see if I can pick anything up, though towards the end of the week will be better. If there is I will follow it. I have captured it below the horizon just over a week ago with a declination of -1 degree – that is to say just the tail showing.As it was pointed out there are other comets around, especially Lovejoy which is nice and easy. Linear X1 is still there but dropped in magnitude, plus quite a few others worth capturing.Tony Angel
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