Hi Greg,
This post by Dave Herald was on the on Canberra Astronomical Society forum this morning. It looks like comet Lovejoy could be around for a while yet.
Hope this helps
Thought people might be interested in this ‘prediction’ of the future brightness of comet Lovejoy. It is by comet expert John Bortle.
If this holds up, we are in for a spectacular sight over the next few weeks. Note that the comet (specifically, its nucleus) gets to its most southerly point on Jan 8, at declination –88 deg. That is, for several weeks after about New Years day the comet will be circumpolar, and therefore visible all night.
This comet is a Kreutz sungrazing comet. For those who would like to learn more about what to expect from this comet, read about this group of comets at:
http://en.wikipedia.org/wiki/Kreutz_Sungrazers
http://en.wikipedia.org/wiki/Sungrazing_comet
For info - Comet Lovejoy had a perihelion distance of 0.0055 AU. This means it skimmed above the surface of the Sun at a distance of about 120,000km, or 1/3rd of the distance between the Earth and the Moon. The radius of the Sun is 696,000 km.....
Dave Herald
Murrumbateman, Australia
************
I am particularly taken by this latest image in that it almost precisely replicates images of Comet Ikeya-Seki from 1965. The match is nearly exact, right down to the distinctly brighter tail edges, the twists in the tail and even the faint outer sheath enveloping the bright dust tail. Such a feature was also seen in some of the drawings of the Great September Comet of 1882. Truly, Kreutz sungrazers are a group of comets absolutely unique unto themselves!
There seems to be some panic arising among folks currently experiencing cloudy skies down under, thinking that they may miss the whole show. Fear not, for as I pointed out previously although the comet's head will continue to fade rapidly, the tail will drop in brightness far more slowly. If it should follow the evolution of the tail of Ikeya-Seki, then the outer-most portion of the long dust tail will hardly fade at all over the next couple of weeks. However, the tail's middle section will, until it has faded to match the end portion. Then the entire tail will seem to fade as a unit. Remember too, that the tail will be continuing to grow throughout the period. I would anticipate the it might attain a final nakedeye length of ~25 degrees, by which time it will be very faint and difficult ghostly specter to the nakedeye.
I was interested to hear that David S. reports variations in the brightness of the tail over the course of a short time, a phenomenon referred to a coruscation. Such has been reported on rare occasions throught cometary history. Although usually attributed to atmospheric instability, some instances have been much harder to explain as such and if seen, it should always be recorded, along with details of the prevailing weather conditions.
J.Bortle