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Comet Mc Naught, (merged with other thread)
Stu
post Jan 6 2007, 05:28 PM
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This has been in the news for a week or so now, with many "experts" predicting it might become very bright around Jan 8-10th in the evening sky as seen from the n hemisphere.

And, after several nights of wasting my time and freezing my fingers off, I'm happy to be able to report my first sighting of Comet McNaught!! Frustrated by great black pillows of cloud in the comet's direction last night, but a very clear WSW horizon tonight lured me back up the sloppy-mud covered track that leads up to Kendal Castle, and from there, at 16.49, I got my first glimpse of the comet. Phew!!

It wasn't visible to the naked eye - well, not my naked eye, anyway - but it is very, very easy to see in binoculars, its head a star-like point and an obvious (and very straight, I thought...) tail stabbing away from it at almost a 45degree angle. The head looked orange-yellowish in my 10x50s, and there seemed, when using averted vision, to be quite a fan-shaped tail sweeping to the upper right. Unfortunately I didn't get to see the comet in a darker sky because it started playing hide and seek behind several horizontal bands of cloud, but my last sighting of it this evening, at 17.05, was very nice... orange-grey sky, streaked with lines of cloud, and Comet McNaught glinting above them like a spark.

Here's hoping others had some luck tonight too! smile.gif


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Guest_Sunspot_*
post Jan 6 2007, 05:51 PM
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Has anyone here managed to spot this potentially brilliant comet? It's VERY low in the sky after sunset or at sunrise but pretty bright. It will make a particularly close pass of the Sun and there are some suggestions it could be visible in daylight to the naked eye for a few days

http://skytonight.com/observing/highlights/5089276.html
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Guest_Myran_*
post Jan 6 2007, 06:02 PM
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I will always remember comet Hyakutake myself, it was the main comet of the last century. It was clearly visible naked eye even with surrounding city light and we did drive off about 2 km near the city limit and there we could see it was spanning half the sky. Before that I always thought the medieval depictions of large comets in the sky had been one exaggeration. But I was wrong, and luckily so.

Good that you spotted the comet eventually then, your work wasnt for naught then. smile.gif
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Stu
post Jan 6 2007, 06:07 PM
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QUOTE (Sunspot @ Jan 6 2007, 05:51 PM) *
Has anyone here managed to spot this potentially brilliant comet? It's VERY low in the sky after sunset or at sunrise but pretty bright. It will make a particularly close pass of the Sun and there are some suggestions it could be visible in daylight to the naked eye for a few days

http://skytonight.com/observing/highlights/5089276.html


Hey sunspot,

I think we started our comet threads at the same time! I saw it tonight! smile.gif smile.gif


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Guest_Sunspot_*
post Jan 6 2007, 06:53 PM
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Nothing seen here... but it has been raining ALL day mad.gif

What did it look like? Was it easy to see?
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nprev
post Jan 7 2007, 02:10 AM
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<clink, clink, clink> southern California light pollution & smog...I couldn't find it, despite clear skies. mad.gif Maybe I'll try for a daylight sighting tomorrow; seems like there's a bare possibility for this.


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Mongo
post Jan 7 2007, 03:40 AM
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Here is a list I made for my own amusement some time ago, of the greatest naked-eye comets of the last two centuries, visible to observers in the northern temperate regions. I used a points system as follows:

MAGNITUDE: 10 points for every degree of magnitude brighter than +3 (dark-sky; daytime magnitude gets counted separately)

TAIL: 1 point for every two degrees of length of naked-eye visible tail in dark sky

DURATION VISIBLE: 1 point for every month naked-eye visible in dark sky

BONUS POINTS:
2 visible tails = 10 points
5 visible tails (West 1976) = 20 points
15 degree long anti-tail (Arend-Roland 1957) = 10 points
curved tail (Donati 1858) = 5 points
'bright' tail (Daylight 1910) = 10 points
'brilliant' tail (Ikeya-Seki 1965, Great September 1882) = 20 points
circumpolar all night (Hyakutake 1996, Tebbutt 1861) = 10 points
Mag. -3 in daylight (West 1976) or Mag. -5 in daylight (Daylight 1910) = 10 points
Mag. -8 in daylight (Great March 1843) = 15 points
Mag. -15 in daylight (Ikeya-Seki 1965) or Mag. -17 in daylight (Great September 1882) = 30 points

1861 123 pts Tebbutt
1882 101 pts Great September Comet
1910 95 pts P/Halley
1976 90 pts West
1996 78 pts Hyakutake
1997 73 pts Hale-Bopp
1858 68 pts Donati
1965 64 pts Ikeya-Seki
1970 61 pts Bennett
1957 57 pts Arend-Roland
1910 54 pts Daylight Comet
1811 52 pts Great Comet
1843 50 pts Great March Comet
1874 46 pts Coggia
1881 42 pts Great Comet
1807 37 pts Great Comet
1853 37 pts Klinkerfues
1835 35 pts P/Halley
1957 35 pts Mrkos
1860 31 pts Great Comet
1911 29 pts Beljawsky
1911 28 pts Brooks
1819 25 pts Tralles
1854 24 pts Great Comet

Here is the same list in reverse chronological order:

1997 73 pts Hale-Bopp
1996 78 pts Hyakutake
1976 90 pts West
1970 61 pts Bennett
1965 64 pts Ikeya-Seki
1957 57 pts Arend-Roland
1957 35 pts Mrkos
1911 29 pts Beljawsky
1911 28 pts Brooks
1910 95 pts P/Halley
1910 54 pts Daylight Comet
1882 101 pts Great September Comet
1881 42 pts Great Comet
1874 46 pts Coggia
1861 123 pts Tebbutt
1860 31 pts Great Comet
1858 68 pts Donati
1854 24 pts Great Comet
1853 37 pts Klinkerfues
1843 50 pts Great March Comet
1835 35 pts P/Halley
1819 25 pts Tralles
1811 52 pts Great Comet
1807 37 pts Great Comet

Bill
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nprev
post Jan 7 2007, 03:57 AM
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QUOTE (Myran @ Jan 6 2007, 10:02 AM) *
Good that you spotted the comet eventually then, your work wasnt for naught then. smile.gif


rolleyes.gif ...okay, so if his work was popular with kids and tasty would it be 'for McNaught'?... biggrin.gif

Mongo: Truly a neat ranking system! smile.gif Sure hope that we're all lucky enough to see a Tebbutt or better some fine day...


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Mongo
post Jan 7 2007, 04:32 AM
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QUOTE (nprev @ Jan 7 2007, 03:57 AM) *
Sure hope that we're all lucky enough to see a Tebbutt or better some fine day...


They do show up once in a while. There was a comet even more spectacular than Tebbutt in the year 1744. Discovered by Dirk Klinkenberg in Dec 1743 and studied by Philippe de Chéseaux, it was a bigger, brighter version of Comet West (1976), with no less than six tails visible at one point (see image here - five tails in that image). Klinkenberg-Chéseaux 1744 reached a magnitude of -6 and was visible in daylight, 12 degrees from the sun. Its tail attained a maximum of 90 degrees under night-time conditions, at which point it was about magnitude -3, for a total of 139 points (without any bonus points for a 'bright' tail, which it would probably have deserved), beating the 123 points of Tebbet 1861.

Bill
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nprev
post Jan 7 2007, 05:04 AM
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I've seen that rendition of the 1744 comet before...even more impressive when you consider that it's a recollection (probably from memory) of a naked-eye observation! blink.gif

Sure hope that the Kreutz group has a few more of these in store...but, sadly, is this a realistic possibility? My impression is that most of the major fragments from the original Kreutz body (errant KBO, I presume), passed perihelion during the middle part of the last millennium.


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Mongo
post Jan 7 2007, 05:26 AM
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There is a chance that Comet McNaught might make that list too. there have been 24 Great Comets in the past 200 years, for an average interval of 8.3 years, and the last Great Comet (Hale-Bopp 1997) was at its most impressive almost 10 years ago. Of course, this means nothing in practical terms -- but we are 'due' for another one.

Here is what comet expert John Bortle has to say about McNaught 2007:

START QUOTE:

As is usually the case for the physical development of a given comet with approach to perihelion, many variables are involved that can not easily be defined beforehand.

Because C/2006 P1 has been so poorly observed up until now, its absolute or intrinsic magnitude, as well as the variable "n", are still quite uncertain and the former figure is typically of great importance in the development of the tails (especially the dust tail). Likewise, particle size relative to sunlight pressure, heliocentric distance and the projection circumstances, all play major rolls in at least the dust tail's apparent length and curvature.

Should Ho be about magnitude 6.5 or fainter, then the dust tail is likely to be fairly weakly and with no more than a few degrees of its length visible in the bright twilight, initially projecting in the same relative direction as calculated for the ion tail around the time of perihelion. One might well expect an appearance similar to a somewhat enhanced version of Ikeya-Zang, or perhaps like Bradfield 2004 F4.

However, if it turns out that C/2006 P1 is actually a major comet, with an Ho around 5 or so, the situation could change rather dramatically (he says, taking a deep and hesitant breath!). In that case, a strong, high surface brightness dust tail is likely to form. And at the same time, tail projection circumstances and the small q should favor much of the length of any dust tail to almost overlap the ion tail for perhaps 1/2 to 2/3's the calculated span, before significantly curving off to the north.

Under the very best of circumstances, from a visual standpoint C/2006 P1 could become a truly spectacular object (especially when factoring in a major forward-scattering event), with possibly a degree or more of tail visible in the daytime, given a really good sky. The overall appearance might be similar to descriptions of the brilliant Comet Skjellerup-Maristan y in 1927, when it was viewed in daylight not far from the Sun.

Immediately following sunset, the comet's head would likely appear a dramatic yellowish hue, due to the strong emission lines of sodium, as would the beginnings of the tail, this often being seen in conjunction with major comets at small q. The intense, almost straight, combined ion-dust tail might be traced 10 or more degrees upwards in the bright sky, with both components becoming much longer as twilight deepens. I would speculate that the overall impression at that time might be somewhat similar to that displayed after sunset by the Great Daylight Comet of 1910, given that the tail projection circumstances happen to be so favorable.

HOWEVER, any such potential grand display is, at the moment, pure speculation. The next few days of twilight observations are likely to tell the true story. And remember, even if C/2006 P1 does develop dramatically, its display is likely to be rather short-lived, both because of the brief duration of the forward-scattering event and the fact that the comet swiftly moves away from the Earth after mid January. So...pray for universally clear weather in mid January!

JBortle

END QUOTE

Bill
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edstrick
post Jan 7 2007, 09:55 AM
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In 1976 or 7, Comet West rounded the sun as a barely news-covered object with a rather small perihelion, and the nucleus split off several chunks, resulting in a massive dust release and spectacular morning apparition as it pulled away from the sun with a quite favorible viewing geometry. It's the most spectacular comet I ever saw, starting with Comet Bennet in about 1970.
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Stu
post Jan 7 2007, 10:28 AM
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Four great comet memories for me...

Standing in a lay-by (that's a small, off-road car parking area, for our non-UK members! smile.gif ) with my long-suffering but ever-patient and understanding mum, staring at Comet IRAS-Araki-Alcock on a chilly night in 1983. It looked like a round chalk smudge in the Little Dipper, very obvious to the naked eye and like a blue-grey puffball in my shaking binoculars. My first "real comet"! smile.gif

Then 1985, Halley's Comet returned. I "found" it on Bonfire Night, (Nov 5th for our US friends), barely-there in binocs in a sky muddied and blurred with the smoke of all the bonfires burning in and fireworks exploding above my town. A shiver literally ran up my spine - it was there, The Comet, Halley's Comet, the one I'd read about for soooooo long - before I shouted "Yes!!" at the sky, causing a nearby dog walker to ask if I was alright... tongue.gif A month or so later I was asked, by her daughter, to go and show the comet to a very old lady who had seen it in 1910. I went up to the house, set up my trusty 3" Tasco reflector, and swung it around to the comet and asked the old lady to come over and look. To be honest, she knew nothing about astronomy, and to save time I could have just aimed at a star and defocussed it to make it look like a comet, but I didn't... and when she peered into the eyepiece a huge smile broke over her face and she started laughing... I asked why, and she said that her father had shown her the comet in 1910, as a girl, and had told her she's never see it again. "You just proved the old b*****d wrong for me, thank you!" she said. Quite a moment! smile.gif

Then, I guess, it would have to be seeing Comet Hyakutake on a blustery night in 1996, standing in the shadow of one of the Lake District's beautiful fells at midnight. The sky was mostly cloudy, just the odd gap floating across here and there... in one of those gaps my observing partner and I saw a "beam" of light. Just a vapour trail, we agreed, as it was surely a) too bright, and cool.gif too far away from the predicted location of the comet's head to be anything to do with Hyakutake... right..? Wrong. Soon after the clouds swept away and there was the comet, painted across the sky like a grey-green lighthouse beam, ridiculously, and I mean ridiculously long. Sweeping it with binoculars we saw brighter areas, clumps, filigree streamers and lines... just beautiful... never forget that...

Finally, standing in the centre of the ancient Castlerigg Stone Circle, on a hillside above Keswick, watching Comet Hale-Bopp rising up from behind another fell, tails first... it looked like someone was shining torches into the sky from behind the fell, the tails were so pronounced, then the head cleared the felltop and standing there, leaning against one of the cold, ancient stones, watching a Great Comet rising, no words were necessary. Beautiful.

McNaught has a lot to live up to... smile.gif


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remcook
post Jan 7 2007, 12:02 PM
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Did anyone put any pictures on the web of the comet yet? They must have, but I didn't find any recent ones with a quick search...

edit - d'oh!
http://www.phys.ncku.edu.tw/~astrolab/mirr...e/ap070105.html


I clearly remember Hale-Bopp, but not Hyakutake... I was a bit young then and not greatly into astronomy.
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Stu
post Jan 7 2007, 12:07 PM
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QUOTE (remcook @ Jan 7 2007, 12:02 PM) *
Did anyone put any pictures on the web of the comet yet?


There's a gallery at Spaceweather.com smile.gif


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