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The Great Christmas Comet of 2011, 2011 W3 (Lovejoy)
Mongo
post Dec 17 2011, 03:29 AM
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Another movie:

SOHO LASCO C3

This site only shows the last 3 days of observation, so it's fine for the next day or so, but after that it will be less useful. But right now, it's spectacular!
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nprev
post Dec 17 2011, 03:34 AM
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ohmy.gif

The next few days may prove interesting...and spectacular for those south of the Equator.


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SteveM
post Dec 17 2011, 03:39 AM
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QUOTE (titanicrivers @ Dec 14 2011, 11:14 PM) *
And check out the SOHO Movie Theater! Choose LASCO C3 and the latest 20 or so images.
http://sohodata.nascom.nasa.gov/cgi-bin/soho_movie_theater
You can trace the entire mind-blowing sequence from entrance to exit by selecting 2011-12-15 as the start date and 2011-12-17 as the end date.
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Guest_Sunspot_*
post Dec 17 2011, 01:10 PM
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Visual sightings starting to come in now.
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Floyd
post Dec 17 2011, 02:31 PM
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Why is the view better from south of the Equater? Unless you are above the artic circle...if you can see the sun, you can see the comet?


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Mongo
post Dec 17 2011, 02:58 PM
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Comet Lovejoy is no longer a daylight comet, so darkish skies are needed to see it with the unaided eye.

Basically, the orbit of this comet appears from Earth at about a 45 degree angle from the ecliptic towards the south. This means that at mid-southern latitudes, the orbit takes the comet almost directly 'above' the sun at sunrise, so that it will be visible (in the coming weeks) well before sunrise, in fairly dark skies. Therefore the contrast of the comet against the sky will be very good, and its tail will be quite visible (and indications are that the tail will become quite lengthy in the coming weeks).

On the other hand, at mid-northern latitudes the comet will be moving away from the sun in a direction almost parallel with the horizon at sunrise, so it will not even appear above the horizon until the sun is nearly rising (and turning the sky very bright), and remain lost in the near-horizon haze until full daylight. The contrast of the comet against the sky will be far worse than from the mid-southern latitudes, and it is likely that it will not even be visible to the naked eye at all, unlike the situation from the mid-southern latitudes where it is expected to be quite prominent in the pre-sunrise sky.

So we have had two Great Comets in a row (McNaught and now with any luck Lovejoy) best seen from the mid-southern latitudes, and poorly visible from the mid-northern hemisphere. Oh well, those are the breaks.
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Floyd
post Dec 17 2011, 06:00 PM
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Thanks Mongo, great explanation!


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MaG
post Dec 17 2011, 08:46 PM
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Our friends took image from Argentina today morning.


http://www.kommet.cz/

And here's my imagination of comet's path in LASCO C3..



What an exciting weekend.


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Mongo
post Dec 18 2011, 10:30 PM
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This was posted today by highly respected astronomer John Bortle on the comets-ml mailing list:

QUOTE
Based on the brightness estimates from early this morning, reported here on comets-ml, it would tentatively seem that comet 2011 W3 is currently only slightly fainter than was Comet Ikeya-Seki at about the same interval post-T and holding its newfound intrinsic brightness. If this is anywhere near correct and that the tail development evident from spacecraft images is at least fairly representative of what might be seen visually, then observers should begin seriously searching for the comet's bright tail projecting up out of the morning twilight beginning at dawn tomorrow.

The tails of some of the major sungrazing comets have been extraordinarily bright. So much so, in fact, that even their exact terminus, usually a vague and extremely ill-defined feature for more typical bright comets, can be clearly evident to the unaided eye. In the case of the Great March Comet of 1843, the Great September Comet of 1882 and 1965's Comet Ikeya-Seki, the tails appeared rather like segments of a bright searchlight beam, so high in their surface brightness that their total length was distinctly obvious to most observers.

Comet Lovejoy's apparition has been so bizarre up to this point that it is truly difficult to anticipate just what might happen next. Even more hazardous would be to attempt to accurately predict the exact sort of tail it will unfurl in the morning sky. However...in my opinion the potential is there for something quite unusual, perhaps even extraordinary, to present itself, particularly by virtue of the current geometry between the comet and Earth, as it presents the most favorable circumstances possible for observing the tail of a Kreutz sungrazing group comet.

I personally await with great anticipation the first reports of Comet Lovejoy's tail as the comet exits the twilight and begins to traverse the morning skies of the Southern Hemisphere. Please...be complete, accurate and as detailed as possible in describing what you see, the coming event may prove historic.

J.Bortle
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nprev
post Dec 18 2011, 10:34 PM
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ohmy.gif ...if John Bortle says anything about comets, I believe it.

Those are some strong words. Wow.


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Stu
post Dec 18 2011, 10:48 PM
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Wow.

Ok, now I really am officially northern hemisphere hacked off. First McNaught dazzles southern hemisphere observers only, now Lovejoy... mad.gif mad.gif mad.gif


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nprev
post Dec 18 2011, 10:55 PM
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Now, now, Stu...we had Hale-Bopp! wink.gif

But, yeah, I feel some hemispherical comet-envy myself here. If I had the money & time my butt would be on the next flight to the most southerly location with good weather predicitions possible.


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scalbers
post Dec 18 2011, 11:33 PM
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QUOTE (Stu @ Dec 18 2011, 10:48 PM) *
Wow.

Ok, now I really am officially northern hemisphere hacked off. First McNaught dazzles southern hemisphere observers only, now Lovejoy... mad.gif mad.gif mad.gif


Just for the record, there were things of interest to observe with McNaught from 40N latitude. Just around perihelion time, it actually was to the NE of the sun and best visible from northern latitudes at mag -5 to -6. I saw it in broad daylight in binoculars, and naked eye just after sunset. Furthermore, the ghostly outer rays of the tail were pointing straight up from the western horizon after evening twilight ended a few days later.

Now with Lovejoy, it was spotted in broad daylight from France - of course a mid-northern latitude - image can be seen at this link:

http://spaceweather.com/submissions/large_..._1324194382.jpg

Really would be interesting to plot this comet's magnitude vs solar elongation in comparison to McNaught and Ikeya-Seki.

Steve


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Mongo
post Dec 19 2011, 12:21 AM
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Report of a daylight sighting of Comet Lovejoy on comets-ml mailing list:

QUOTE
Daylight Comet!

by Rick Baldridge



The amazing happened. Comet Lovejoy (C/2011 W3) survived what was thought to be a suicide plunge into the solar corona, passing only 78,800 miles from the surface of the Sun on December 16th not quite 1/10th a solar diameter! Surprisingly, the comet reappeared on SOHO LASCO images barely 1 hour after perihelion passage, prompting Brian Day of NASA/Ames and I to attempt a daylight observation.

We ran up to Foothill College Observatory (Los Altos Hills, CA) at lunch time on Dec 16th and opened up the dome. I quickly made a 3" aperture off-axis mask for the Meade 16" Schmidt scope, which allowed me to use the dome shutter as a glare shield, keeping direct sunlight out of the telescope tube assembly. Comet Lovejoy was barely 4 west of the sun during the attempted observation.

Finding Venus first to focus on, I used coordinates from JPL HORIZONS to center the `scope on the comet's expected position. After looking through a 127x eyepiece for a few moments THERE IT WAS! A very star-like nucleus with a faint but obvious fan shaped glow streaming away from it. The fan was maybe 20 arc-seconds long. A very rough guess was the nucleus was magnitude -1, based on my impression of the appearance of Mercury years ago at a similar solar elongation. This initial sighting came at 11:48am PST (Dec 16th at 19:48UT)

Brian Day was quickly called, who had just driven into the Observatory parking lot. He came up, took one look in the eyepiece, and after adapting to the brightness of the background sky, exclaimed, "DAMN! There it is!"

We were ecstatic! Seeing a daylight comet is an extremely rare thing, and so close to the sun only 4 degrees. Truly amazing!

Unfortunately, Brian and I did not have our DSLRs to attempt taking a photo. We tried our cell phone cameras, holding the lens up to the eyepiece using afocal projection, but to no avail.

It was an experience we will never forget!
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nprev
post Dec 19 2011, 12:58 AM
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Wow.

Mongo, please keep feeding salient info like this at your discretion. I think that there is a SLIGHT chance that this thing might be visible to unskilled observers over the next few days, and anything we can do to promulgate awareness would be very useful. Thanks!!!


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