mountain profile Institute for Astronomy University of Hawaii

ISON Today: Updates from Karen Meech

December 1

ISON is fading fast, and even those with prime viewing conditions are not seeing anything.

 

November 30

While something has survived perihelion passage, it doesn't look good for poor ISON. The SOHO observatory LASCO images from this morning, shown below show a dust cloud that seems to be spreading out.

Hermann Boehnhardt from the MPS in Germany has done an analysis of the dust and concludes

"2 diffuse tail structures were analysed in post-perihelion images obtained by the LASCO-C3 corongraph onbord SOHO on 29 Nov. 2013 between 14.5 and 19.5UT. [ . . . ] the eastward tail can best be interpretated as being caused by a dust release about 1h around perihelion. [The analysis can be interpreted as being typical for] graphite or metallic grains of about 0.1 micron radius. No indications are found for a continuation of the release of similar dust after 2h post-perihelion. The shorter southward tail may be a relict of heavier grains released about 1 to 2 days before perihelion passage.

Astronomer Luisa Lara from Granada Spain passed around a picture her friend from Spain took in the evening 11/29 from Granada shortly after sunset. Other astronomers are a bit skeptical about the photo because it should have been too close to the sun to see, and in the bright sky it would have been hard to catch a magnitude 1-3 fuzzy object. Other agree it would still be very hard to see right now, but that the best time to look for the "remnant dust cloud" might be mid Jan close to the Earth passage on 1/16.

Some commonly asked questions :

1. The big question is - did the comet survive or is this just a dust pile? We may not know until HST can look at it in late December.-- Karl Battams

2. Can we see it naked eye...... Karl Battams says the current brightness in LASCO is +5 and fading, so it seems a bit untlikely.... but he hopes he's wrong. The best chance might be middle to end of next week.

Spectacular animations of the STEREO view of the ISON encounter can be found at:
http://www.isoncampaign.org/karl/a-trail-of-questions

 

November 29

At least some part of the comet survived the perihelion passage . . . The latest SOHO LASCO images show two dust tails. From our colleagues at the MPS in Germany, Hermann Boehnhardt reports:

"The sunward tail contains old dust emitted long before perihelion passage. The northward pointing tail contains dust released shortly before and possible after perihelion passage. In the coming hours more will be learned from the dust tail about the post-perihelion activity of the comet."

 

ISON