The Great Christmas Comet of 2011, 2011 W3 (Lovejoy) Options

[Guest_Sunspot_*]

http://sungrazer.nrl.navy.mil/index.php?p=.../birthday_comet

Possible very bright sungrazing comet coming mid December - Comet Lovejoy C/2011 W3 (Lovejoy)

Information in the link above.

[Mongo]

From comet-ml post #18958:

Hi all,

When I first looked out this morning (from Cowra in central NSW) and saw the layers of high and middle-level cloud, I almost went back to bed. But after a few minutes deciding, I set up the 25x100 binocular telescope and started to sweep along the horizon which, surprisingly, was clear for the first two or three degrees. At 4.20 local summer time (1720 UT) I noticed something like a distant searchlight beam rising over the slope of a small hill which sports the rather grandiose name of "Porter's Mount". With the sky becoming bright, I could see a clear feature on the local horizon (a tree about two thirds of the way up the grassland slope of Porter's Mount) near where the beam emerged and, finding this without the telescope, I could then see about 2 - 3 degrees of tail rising up to a bank of heavy cloud. The tail must have been quite intense to be seen in such a bright sky and, from the calculated position of the head, at least 7 - 8 degrees long (although most of this was not seen. Neither was the head as the sky had become very bright by the time it would have cleared Porter's Mount).

On a slightly different topic, as one of the few Ikeya-Seki veterans in this group, it is probably timely to sound a warning not to give up on this comet because of the degree of fading that has obviously taken place. Back in 1965, the arrival of I-S at perihelion was surrounded by a lot of media hype. Predictions that a comet brighter than the Moon was coming, while they turned out to be technically true, failed to make clear that the comet would be only a few arcminutes from the Sun's limb at that time and would fade very rapidly afterwards. Of course, the general public missed much of the display at perihelion and dismissed the comet as a dud. On the day of perihelion, Fred Whipple called it "a scientist's comet"; one that was great for astronomers but a disappointment for the public. Unfortunately, the media dropped the subject (by and large) and when the "public" show occurred over a week later, only those who normally rose before dawn for work or other purposes saw it.

My first couple of views post perihelion were not all that exciting. High cloud always seemed to shroud the eastern horizon and by the time the comet cleared this, the sky was very bright and the comet looked washed out with only a small diffuse spot of a coma and a fading tail. Then, exactly 10 days after perihelion, there was a morning of exceptional clarity and by that time the comet was far enough from the Sun to be rising in a dark sky. The sight was magnificent. In the dark sky, the coma appeared brighter than the earlier twilight views and looked small and dense. As for the tail, this appeared (as John Bortle has written on several occasions to this group) "solid", not diaphanous like the tail of a normal comet. And there was little "normal" about Ikeya-Seki! Today, we would probably think of laser beams or Star-Wars light sabres ... but this was back in 1965!!

Now, I am certainly not saying that W3 will become as remotely spectacular as I-S, but the lessons of 1965 are worth noting. The comet may become faint, but the tail may well retain relatively high surface brightness for quite some time and be impressive in coming days as it pulls out from the twilight (and moonlight). Don't dismiss this comet just yet! There may still be surprises in store.

David

In response to this, John Bortle wrote in comet-ml post #18961:

David is absolutely correct. I anticipate that the spectacle is only likely to grow better with time as the tail moves out of the morning twilight. Keep in mind that the brightness of a sungrazer's dust tail seems to fade much more slowly than does that of the coma, following closer to a rate dictated by the inverse square law. Likewise, Comet Lovejoy's tail is more-or-less still approaching Earth as the comet retreats from the Sun, slowing the fading process even further.

Go back and consult some of my earlier posts concerning the development of Comet Ikeya-Seki's post-T dust tail. Such may well foreshadow the sort of evolutionary path that the tail of Comet Lovejoy may see in days to come on a somewhat more modest scale.

Folks, be assured that the show isn't over yet by any means.

J.Bortle