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Main
Date: 22 Oct 2006 09:08:39
From: rdeol85@gmail.com
Subject: Any good memorable comets coming soon? Like Ikeya-Zhang Hale-Bopp
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Just curious if I am ever going to get the chance to see a grand naked
eye comet with a telescope any time soon.
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Date: 22 Oct 2006 16:53:23
From: David Nakamoto
Subject: Re: Any good memorable comets coming soon? Like Ikeya-Zhang Hale-Bopp
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Truthfully, play the lottery; your chances of hitting the big times with
the Lottery are about as good as what the chances are for the next great
comet.
Comets are unpredictable. Ask anyone about Kohoetek, as one example.
And you need to watch the astronomy news closely; Hyakutake came and
went almost before we had the chance to get the news out.
--- Dave
rdeol85@gmail.com wrote:
> Just curious if I am ever going to get the chance to see a grand naked
> eye comet with a telescope any time soon.
>
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Date: 22 Oct 2006 17:05:54
From: Chris L Peterson
Subject: Re: Any good memorable comets coming soon? Like Ikeya-Zhang Hale-Bopp
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On Sun, 22 2006 16:53:23 GMT, David Nakamoto
<david.nakamoto@verizon.net > wrote:
>Truthfully, play the lottery; your chances of hitting the big times with
>the Lottery are about as good as what the chances are for the next great
>comet.
Or not. Most people can expect to see one or two great naked eye comets
in their lifetime. But even if you played the lottery every day, you'll
need many lifetimes to have a significant chance of "hitting the big
times".
Granted, there is some looseness as to what constitutes a "great" comet.
I clearly recall three I'd place in that category: West, Hyakutake, and
Hale-Bopp. And I recall another half-dozen or so naked eye comets that
were bright enough to see a tail- all of which were spectacular in
binoculars ("almost great"? "real good?"). And all of those in less than
30 years. Better than my lottery record!
_________________________________________________
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com
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Date: 24 Oct 2006 18:28:18
From: David Nakamoto
Subject: Re: Any good memorable comets coming soon? Like Ikeya-Zhang Hale-Bopp
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Chris L Peterson wrote:
> On Sun, 22 2006 16:53:23 GMT, David Nakamoto
> <david.nakamoto@verizon.net> wrote:
>
>> Truthfully, play the lottery; your chances of hitting the big times with
>> the Lottery are about as good as what the chances are for the next great
>> comet.
>
> Or not. Most people can expect to see one or two great naked eye comets
> in their lifetime. But even if you played the lottery every day, you'll
> need many lifetimes to have a significant chance of "hitting the big
> times".
Good point.
> Granted, there is some looseness as to what constitutes a "great" comet.
> I clearly recall three I'd place in that category: West, Hyakutake, and
> Hale-Bopp. And I recall another half-dozen or so naked eye comets that
> were bright enough to see a tail- all of which were spectacular in
> binoculars ("almost great"? "real good?"). And all of those in less than
> 30 years. Better than my lottery record!
Another good point.
So we should get out there and try and discover the next Great Comet
rather than play the lottery . . . . except that there is little
monetary return on discovering a Great Comet, Hale not withstanding.
--- Dave
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Date: 24 Oct 2006 13:17:00
From: Greg Crinklaw
Subject: Re: Any good memorable comets coming soon? Like Ikeya-Zhang Hale-Bopp
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David Nakamoto wrote:
> So we should get out there and try and discover the next Great Comet
> rather than play the lottery . . . . except that there is little
> monetary return on discovering a Great Comet, Hale not withstanding.
^^^^^^^^^^^^^^^^^^^^^
LOL!
--
Greg Crinklaw
Astronomical Software Developer
Cloudcroft, New Mexico, USA (33N, 106W, 2700m)
SkyTools: http://www.skyhound.com/cs.html
Observing: http://www.skyhound.com/sh/skyhound.html
Comets: http://www.skyhound.com/sh/comets.html
To reply take out your eye
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Date: 22 Oct 2006 13:12:43
From: CNJ999
Subject: Re: Any good memorable comets coming soon? Like Ikeya-Zhang Hale-Bopp
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In point of fact, there hasn't been a "classic" Great Comet is 30
years. While H-B and Hyakutake were in a sense rather spectacular, the
brightness of either's tail (usually the most outstanding feature of a
Great Comet) were but pale representations of what nearly all of the
Great Comets of the past have displayed. If we ever do get another
truly Great Comet, I expect today's observers will be utterly shocked
by its overall brilliance.
The best time to have been an amateur astronomer interested in comets
was between 1957 and 1976, when Great Comets were literally
commonplace, with at least half a dozen appearing in the short span of
just 20 years! In fact, it was the most prolific period for such
objects in recorded history. The only similar grouping of truly
briilliant comets took place about a century earlier than that and
there are no other contenders for the title. So...as pointed out up
stream...the typical historical odds for seeing a classical Great Comet
are no better than perhaps 2 or 3 over the course of a lifetime. Thus,
if you're wating for one...don't hold your breath!
JBortle
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Date: 22 Oct 2006 16:24:00
From: Stephen Paul
Subject: Re: Any good memorable comets coming soon? Like Ikeya-Zhang Hale-Bopp
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CNJ999 wrote:
> In point of fact, there hasn't been a "classic" Great Comet is 30
> years. While H-B and Hyakutake were in a sense rather spectacular, the
> brightness of either's tail (usually the most outstanding feature of a
> Great Comet) were but pale representations of what nearly all of the
> Great Comets of the past have displayed. If we ever do get another
> truly Great Comet, I expect today's observers will be utterly shocked
> by its overall brilliance.
>
> The best time to have been an amateur astronomer interested in comets
> was between 1957 and 1976, when Great Comets were literally
> commonplace, with at least half a dozen appearing in the short span of
> just 20 years! In fact, it was the most prolific period for such
> objects in recorded history. The only similar grouping of truly
> briilliant comets took place about a century earlier than that and
> there are no other contenders for the title. So...as pointed out up
> stream...the typical historical odds for seeing a classical Great Comet
> are no better than perhaps 2 or 3 over the course of a lifetime. Thus,
> if you're wating for one...don't hold your breath!
>
> JBortle
>
I want to know what the comet was that was clearly visible somewhere
between 1965 and 1970, here in Massachusetts. My stepfather woke me up
early in the morning to go out and see it. I'm sure he said it was "The
Milkman's Comet", but I haven't found any reference to it anywhere.
I distinctly remember it being high in the sky, very bright, and with a
short hooked tail. Of course I was a pretty young, and the memory is
quite old now. It was the first comet I ever saw.
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Date: 22 Oct 2006 22:31:59
From: Mark Gingrich
Subject: Re: Any good memorable comets coming soon? Like Ikeya-Zhang Hale-Bopp
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Stephen Paul wrote:
> I want to know what the comet was that was clearly visible somewhere
> between 1965 and 1970, here in Massachusetts. My stepfather woke me up
> early in the morning to go out and see it. I'm sure he said it was "The
> Milkman's Comet", but I haven't found any reference to it anywhere.
>
> I distinctly remember it being high in the sky, very bright, and with a
> short hooked tail. Of course I was a pretty young, and the memory is
> quite old now. It was the first comet I ever saw.
This sounds like Comet Bennett, which hovered conspicuously above the
pre-dawn eastern horizon in March/April of 1970. I'd heard about it
from the newspaper delivery boy who lived down the street. And when
I went out early the next morning to investigate, I'm sure I awakened
the entire neighborhood with my uncontrollably loud yell of "whoa!"
--
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
Mark Gingrich grinch@rahul.net San Leandro, California
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Date: 22 Oct 2006 17:10:31
From: Howard Lester
Subject: Re: Any good memorable comets coming soon? Like Ikeya-Zhang Hale-Bopp
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"Mark Gingrich" wrote
> This sounds like Comet Bennett, which hovered conspicuously above the
> pre-dawn eastern horizon in March/April of 1970. I'd heard about it
> from the newspaper delivery boy who lived down the street. And when
> I went out early the next morning to investigate, I'm sure I awakened
> the entire neighborhood with my uncontrollably loud yell of "whoa!"
Are you sure that's what you yelled? :-) I'm sure I said something a
little more descriptive when I saw it from the suburbs of NYC. It was bright
enough that I still got an excellent photo of it in twilight on Ektachrome
64.
Comet West in 1976 may have been even brighter, as seen over suburban
Seattle, but I could only get one short look as I was completely "out of it"
from the flu.
Howard
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Date: 23 Oct 2006 01:13:55
From: Mark Gingrich
Subject: Re: Any good memorable comets coming soon? Like Ikeya-Zhang Hale-Bopp
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Howard Lester wrote:
> Are you sure that's what you yelled? :-) I'm sure I said something a
> little more descriptive when I saw it from the suburbs of NYC. ...
Howard, I fail to see how the statement "Let's go, Mets!" would qualify
as "something a little more descriptive." ;)
--
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
Mark Gingrich grinch@rahul.net San Leandro, California
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Date: 23 Oct 2006 06:27:44
From: Howard Lester
Subject: Re: Any good memorable comets coming soon? Like Ikeya-Zhang Hale-Bopp
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"Mark Gingrich" wrote
> Howard Lester wrote:
>
>> Are you sure that's what you yelled? :-) I'm sure I said something a
>> little more descriptive when I saw it from the suburbs of NYC. ...
>
>
> Howard, I fail to see how the statement "Let's go, Mets!" would qualify
> as "something a little more descriptive." ;)
..Especially before the season even started! It was the miracle comet - a
reward for the Miracle Mets just 5 months earlier. Wait - comets of fortune
are supposed to arrive beFORE the blessed event.... whoops!
;-)
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Date: 22 Oct 2006 19:06:49
From: Stephen Paul
Subject: Re: Any good memorable comets coming soon? Like Ikeya-Zhang Hale-Bopp
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Mark Gingrich wrote:
> Stephen Paul wrote:
>
>> I want to know what the comet was that was clearly visible somewhere
>> between 1965 and 1970, here in Massachusetts. My stepfather woke me up
>> early in the morning to go out and see it. I'm sure he said it was "The
>> Milkman's Comet", but I haven't found any reference to it anywhere.
>>
>> I distinctly remember it being high in the sky, very bright, and with a
>> short hooked tail. Of course I was a pretty young, and the memory is
>> quite old now. It was the first comet I ever saw.
>
>
> This sounds like Comet Bennett, which hovered conspicuously above the
> pre-dawn eastern horizon in March/April of 1970. I'd heard about it
> from the newspaper delivery boy who lived down the street. And when
> I went out early the next morning to investigate, I'm sure I awakened
> the entire neighborhood with my uncontrollably loud yell of "whoa!"
>
Thanks Mark. I did some searching for images of this comet. Looks right.
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Date: 23 Oct 2006 07:24:13
From: CNJ999
Subject: Re: Any good memorable comets coming soon? Like Ikeya-Zhang Hale-Bopp
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Paul - Regarding you comments, there is nothing subjective about my
statement. To the average amateur astronomer who saw H-B or Hyakutake,
from a typical observing site, many comets of the past were far more
spectacular in overall impressiveness.
Indeed, I saw Hyakutake on a number of nights from a site with
excellent sky conditions and could trace the tail 70 degrees
(incidentally, the reported 100+ degree tails were nonsense and
physically quite impossible under the circumstances). However, that
comet's tail was of quite low surface brightnes and the typical amateur
report credited it with a length of more like 10-15 degrees and very
faint at that. Likewise, while H-B did have a nice bright coma, except
for the first few dgrees, its tail was generally of low surface
brightness as well and relatively few amateurs saw more than ten
degrees or so in its span.
There is no selective memory involved when I say that the perhaps half
a dozen Great Comets visible between 1957 and 1976 out-shown both H-B
or Hyakutake. In fact, I saw each and, since comets have always been my
specialty, I can objectively compare one with another, having viewed
them all under equally good skies and with considerable observing
experience.
1957 Arend-Roland. Peaked at -1, displayed very bright anti-solar AND
sunward-pointing tails, spanning a total of 45 degrees.
1962 Seki-Lines. Reached -3 and had an intensely bright, dramatically
curved, 20 degree tail.
1965 Ikeya-Seki. Visible briefly in the daytime with the unaided eye
with a magnitude of -8 to -14. After perihelion passage it unfurled a
25 degree tail with the highest surface brightness of any comet in the
20th century, looking over its entire length like a brilliant auroral
ray. Fully 15-20 degrees of nakedeye tail wase even reported visible
from within NYC!
1970 Bennett. Zero magnitude with a 20-25 degree, brilliant, tail. I
recall one morning watching this comet rise, complete with 5 degrees of
tail, from indoors while seated in the room watching TV with the room
lights on and simply glancing out through a closed window, waiting for
it to get up enough to properly observe!
1976 West. Attained -3; visible during the daytime with binoculars
looking like a fuzzy version of Venus and seen before sunset with just
the unaided eye. It displayed 5 tails (the result of its nucleus
breaking up into independant comets), the longest attaining fully 35
degree and showing a distinct deep reddish color!
In addition, during this same period, there were somewhat lesser but
still very bright comets like Comet Mrkos, of zero to first magnitude
with a 15 degree tail in 1957, Comet Wilson-Hubbard in 1961 at 2nd to
3rd magnitude with a 25 degree tail. Plus, Comet Pereyra, 3rd magnitude
with a 15 degree tail in 1963 and White-Ortiz-Bolelli in 1970 at 1st to
2nd magitude and displaying a dozen degrees of tail.
Any of these first 5 or 6 most any observer today would placed well
above H-B or Hyakutake if they had a chance to compare them side by
side. Just because you or those today have never seen objects of such
grandeur, don't think they are products of a hazy memory. You'll be
convinced when a really good one comes along again.
JBortle
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Date: 23 Oct 2006 11:44:25
From: Howard Lester
Subject: Re: Any good memorable comets coming soon? Like Ikeya-Zhang Hale-Bopp
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"CNJ999" wrote
> 1970 Bennett. Zero magnitude with a 20-25 degree, brilliant, tail. I
> recall one morning watching this comet rise, complete with 5 degrees of
> tail, from indoors while seated in the room watching TV with the room
> lights on and simply glancing out through a closed window, waiting for
> it to get up enough to properly observe!
>
> 1976 West. Attained -3; visible during the daytime with binoculars
> looking like a fuzzy version of Venus and seen before sunset with just
> the unaided eye. It displayed 5 tails (the result of its nucleus
> breaking up into independant comets), the longest attaining fully 35
> degree and showing a distinct deep reddish color!
> Any of these first 5 or 6 most any observer today would placed well
> above H-B or Hyakutake if they had a chance to compare them side by
> side. Just because you or those today have never seen objects of such
> grandeur, don't think they are products of a hazy memory. You'll be
> convinced when a really good one comes along again.
Agreed. I saw both Bennett and West in suburban skies, and both outshone
both Hale-Bopp and Hyakutake in dark skies. While the latter two were
probably seen by a few million more people than Bennett and West (both early
morning comets), they were not as intrinsically "great."
Howard
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Date: 28 Oct 2006 15:19:19
From: David Knisely
Subject: Re: Any good memorable comets coming soon? Like Ikeya-Zhang Hale-Bopp
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J. Bortle wrote:
> Indeed, I saw Hyakutake on a number of nights from a site with
> excellent sky conditions and could trace the tail 70 degrees
> (incidentally, the reported 100+ degree tails were nonsense and
> physically quite impossible under the circumstances). However, that
> comet's tail was of quite low surface brightnes and the typical amateur
> report credited it with a length of more like 10-15 degrees and very
> faint at that. Likewise, while H-B did have a nice bright coma, except
> for the first few dgrees, its tail was generally of low surface
> brightness as well and relatively few amateurs saw more than ten
> degrees or so in its span.
Impossible? Well, only if the tail was completely straight (and there
was no subtle dust tail contribution which might have been seen about
the time of closest approach to Earth). There have been some arguments
about maximum tail length, but I believe that some analysis published in
Sky and Telescope at one time showed that it was possible for some
mechanism (other than pure geometry) to produce an observed tail length
of more than 90 degrees. As for the visual appearance, I did see a tail
length than definitely exceeded 60 degrees, although the tail was not as
bright as those of Hale-Bopp's or West's. I had a little difficulty
with getting a maximum tail length estimate at one time, as the tail
entered the Gegenschein as seen from my dark sky site. Hyakutake showed
a 25 degree long tail which was faint but easily seen by the public at
Hyde Observatory on a night (March 26th, 1996) when the first quarter
moon was in the sky (and this is in a park inside a city of nearly
200,000). This, at least in my book, does qualify Comet Hyakutake to be
considered a "great" comet. Clear skies to you.
--
David W. Knisely KA0CZC@navix.net
Prairie Astronomy Club: http://www.prairieastronomyclub.org
Hyde Memorial Observatory: http://www.hydeobservatory.info/
**********************************************
* Attend the 13th Annual NEBRASKA STAR PARTY *
* July 23-28, 2006, Merritt Reservoir *
* http://www.NebraskaStarParty.org *
**********************************************
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Date: 29 Oct 2006 09:42:39
From: Paul Schlyter
Subject: Re: Any good memorable comets coming soon? Like Ikeya-Zhang Hale-Bopp
|
In article <1161613453.078069.109830@m73g2000cwd.googlegroups.com >,
CNJ999 <jbortle@aol.com > wrote:
> In point of fact,
Rephrase that to "In point of my opinion" .... see below:
> there hasn't been a "classic" Great Comet is 30
> years. While H-B and Hyakutake were in a sense rather spectacular, the
> brightness of either's tail (usually the most outstanding feature of a
> Great Comet) were but pale representations of what nearly all of the
> Great Comets of the past have displayed. If we ever do get another
> truly Great Comet, I expect today's observers will be utterly shocked
> by its overall brilliance.
I don't know how easily shocked you are, but I actually saw two of
those comets you refer to below. It was fun, and I enjoyed them --
but I wasn't at all "utterly shocked" - instead I felt quite happy!
But I was more impressed by Hyakutake and though Hale-Bopp was quite
similar in "greatness". Read on....
> The best time to have been an amateur astronomer interested in comets
> was between 1957 and 1976, when Great Comets were literally
> commonplace, with at least half a dozen appearing in the short span of
> just 20 years!
"at least half a dozen" = at least 6, probably more ..... but below you
list only five comets...... :-)
> In fact, it was the most prolific period for such
> objects in recorded history. The only similar grouping of truly
> briilliant comets took place about a century earlier than that and
> there are no other contenders for the title. So...as pointed out up
> stream...the typical historical odds for seeing a classical Great Comet
> are no better than perhaps 2 or 3 over the course of a lifetime. Thus,
> if you're wating for one...don't hold your breath!
>
> JBortle
>
>
>
>
>
>
>
>
> Paul - Regarding you comments, there is nothing subjective about my
> statement.
:-)
> To the average amateur astronomer who saw H-B or Hyakutake,
> from a typical observing site, many comets of the past were far more
> spectacular in overall impressiveness.
Ah, there's the catch: a "typical observing site" is today much more
light polluted than it was 100 or even 50 years ago.
> Indeed, I saw Hyakutake on a number of nights from a site with
> excellent sky conditions and could trace the tail 70 degrees
> (incidentally, the reported 100+ degree tails were nonsense and
> physically quite impossible under the circumstances). However, that
> comet's tail was of quite low surface brightnes and the typical amateur
> report credited it with a length of more like 10-15 degrees and very
> faint at that. Likewise, while H-B did have a nice bright coma, except
> for the first few dgrees, its tail was generally of low surface
> brightness as well and relatively few amateurs saw more than ten
> degrees or so in its span.
>
> There is no selective memory involved when I say that the perhaps half
> a dozen Great Comets visible between 1957 and 1976 out-shown both H-B
> or Hyakutake.
True, however you do make things a bot over-simple when you consider
the "greatness" of comet to merely be its peak magnitude. Other things
matter too -- such as whether the comet at peak brightness can be seen
only in twilight skies, or if they also can be seen in fully dark skies
and if so, how high up in the sky the comet appears.
To me, it takes more to be impressed by a comet than to read a table
of peak magnitudes and there read "-3" .....
> In fact, I saw each and, since comets have always been my
> specialty, I can objectively compare one with another,
Now you're starting to sound like Percival Lowell: he was an expert on
MArs, and probably considered himself to be able to objectively observe
the surface features of that planet.....
> having viewed them all under equally good skies and with considerable
> observing experience.
Sorry, but a bright twilight sky isn't an "equally good sky" as a fully
dark sky!
> 1957 Arend-Roland. Peaked at -1, displayed very bright anti-solar AND
> sunward-pointing tails, spanning a total of 45 degrees.
>
> 1962 Seki-Lines. Reached -3 and had an intensely bright, dramatically
> curved, 20 degree tail.
>
> 1965 Ikeya-Seki. Visible briefly in the daytime with the unaided eye
> with a magnitude of -8 to -14. After perihelion passage it unfurled a
> 25 degree tail with the highest surface brightness of any comet in the
> 20th century, looking over its entire length like a brilliant auroral
> ray. Fully 15-20 degrees of nakedeye tail wase even reported visible
> from within NYC!
>
> 1970 Bennett. Zero magnitude with a 20-25 degree, brilliant, tail. I
> recall one morning watching this comet rise, complete with 5 degrees of
> tail, from indoors while seated in the room watching TV with the room
> lights on and simply glancing out through a closed window, waiting for
> it to get up enough to properly observe!
>
> 1976 West. Attained -3; visible during the daytime with binoculars
> looking like a fuzzy version of Venus and seen before sunset with just
> the unaided eye. It displayed 5 tails (the result of its nucleus
> breaking up into independant comets), the longest attaining fully 35
> degree and showing a distinct deep reddish color!
>
> In addition, during this same period, there were somewhat lesser but
> still very bright comets like Comet Mrkos, of zero to first magnitude
> with a 15 degree tail in 1957, Comet Wilson-Hubbard in 1961 at 2nd to
> 3rd magnitude with a 25 degree tail. Plus, Comet Pereyra, 3rd magnitude
> with a 15 degree tail in 1963 and White-Ortiz-Bolelli in 1970 at 1st to
> 2nd magitude and displaying a dozen degrees of tail.
>
> Any of these first 5 or 6
Let's count them - above you listed:
1. 1957 Arend-Roland.
2. 1962 Seki-Lines.
3. 1965 Ikeya-Seki.
4. 1970 Bennett.
5. 1976 West.
Yep, that's 5, not 6. And 5 isn't "at least half a dozen" ..... but I
suppose there's nothing subjective about your phrase here either.... :-)
In your list above you forgot Comet Kohoutek, which in Febr 1974
peaked at magnitude -3, but then it was so close to the Sun in the
sky that only astronauts onboard Skylab could observe it.
Nevertheless, by your simpleminded criterion "the greatness of a
comet depends only on its peak magnitude", Kohoutek should definitely
be included too - after all, it became about as bright as Comet West,
although people on Earth never had the chance to admire its full
splendor. Adding Kohoutek to your list will also perhaps save your
face, since 6 is indeed "at least half a dozen" by a minimum margin....
> most any observer today would
...perhaps you should let "most any observer" speak for themselves
instead of putting your words into their mouths?
> placed well above H-B or Hyakutake if they had a chance to compare
> them side by side.
...which you know cannot be done. Put e.g. Ikeya-Seki of 1965 "side
by side" with Hyakutake right overhead in a fully dark sky - you know
what? If you did so, Ikeya-Seki would lose almost all of its grandeur,
because it would (for geometrical reasons) then have to be put much
farther from the Sun (around 1 AU) than it actually was.
> Just because you or those today have never seen objects of such grandeur,
You're so full of prejudice !!! FYI: I saw both Bennett and West -- don't
tell me I didn't see them! And I don't think I'm the only one here who
saw them....
> don't think they are products of a hazy memory. You'll be convinced
> when a really good one comes along again.
>
> JBortle
There's really only one reasonable way a comet could be intrinsically
brighter - by passing closer to the Sun at perihelion.: the closer to
the Sun, the brighter the comet will become. The most outstanding
examples here are of course the Kreutz family of comets, the last
really bright example of which was Ikeya-Seki in 1965. However, all
such comets will by necessity always appear in twilight skies, quite
close to the Sun in the sky. Bennet and West, both of which I was
back in 1970 and 1976, were both in twilight skies when brightest.
Hyakutake and Hale-Bopp could be seen in dark skies when brightest.
That made them more impressive, even though they were a bit fainter.
I'm not quite sure whan I would consider most impressive: a mag -5
comet in a bright twilight sky, or a mag 0 comet right overhead in a
completely dark night sky. In our times, the former is of course more
appealing on one way: it is less sensitive to light pollution.
But I don't expect to ever again see a comet of magnitude zero or
brighter, with a long tail, near to my local zenith in a fully
dark sky.... (for that to happen, the comet must be at least some
120 degrees away from the Sun in our sky -- Ikeya-Seki, Bennet or
West never managed to do that while still bright).
As you can see, the "greatness" of a comet is quite subjective: you
consider almost only the peak brightness of the comet, while I think
other circumstances is important too.
--
----------------------------------------------------------------
Paul Schlyter, Grev Turegatan 40, SE-114 38 Stockholm, SWEDEN
e-mail: pausch at stockholm dot bostream dot se
WWW: http://stjarnhimlen.se/
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Date: 23 Oct 2006 10:45:19
From: Johnny Borborigmi
Subject: Re: Any good memorable comets coming soon? Like Ikeya-Zhang Hale-Bopp
|
On 2006-10-22 16:12:43 -0400, "CNJ999" <jbortle@aol.com > said:
>
> In point of fact, there hasn't been a "classic" Great Comet is 30
> years. While H-B and Hyakutake were in a sense rather spectacular, the
> brightness of either's tail (usually the most outstanding feature of a
> Great Comet) were but pale representations of what nearly all of the
> Great Comets of the past have displayed. If we ever do get another
> truly Great Comet, I expect today's observers will be utterly shocked
> by its overall brilliance.
Hale-Bop was a great comet, c'mon there's no denying it. Easy naked
eye, you looked up and there it was hanging in the sky.
I don't care what the "pros" say, that was a great comet.
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Date: 23 Oct 2006 14:12:55
From: Chris L Peterson
Subject: Re: Any good memorable comets coming soon? Like Ikeya-Zhang Hale-Bopp
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On Mon, 23 2006 10:45:19 GMT, Johnny Borborigmi <growl@tummy.com >
wrote:
>Hale-Bop was a great comet, c'mon there's no denying it. Easy naked
>eye, you looked up and there it was hanging in the sky.
>
>I don't care what the "pros" say, that was a great comet.
Indeed. And in fact, "pros" don't have a definition for "great comet".
IMO a "great comet" is any comet seen by large numbers of people, and
which becomes a significant topic of interest outside the astronomical
community. Certainly Hale-Bopp and Hyakutake (which is the most
spectacular astronomical object I've ever seen) both fall in this
category.
_________________________________________________
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com
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Date: 23 Oct 2006 13:14:06
From: Paul Schlyter
Subject: Re: Any good memorable comets coming soon? Like Ikeya-Zhang Hale-Bopp
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In article <2006102306451975249%growl@tummycom >,
Johnny Borborigmi <growl@tummy.com > wrote:
>On 2006-10-22 16:12:43 -0400, "CNJ999" <jbortle@aol.com> said:
>
>>
>> In point of fact, there hasn't been a "classic" Great Comet is 30
>> years. While H-B and Hyakutake were in a sense rather spectacular, the
>> brightness of either's tail (usually the most outstanding feature of a
>> Great Comet) were but pale representations of what nearly all of the
>> Great Comets of the past have displayed. If we ever do get another
>> truly Great Comet, I expect today's observers will be utterly shocked
>> by its overall brilliance.
>
>
>Hale-Bop was a great comet, c'mon there's no denying it. Easy naked
>eye, you looked up and there it was hanging in the sky.
>
>I don't care what the "pros" say, that was a great comet.
It was indeed. And Hale-Bopp was unique in one respect: no other
comet in recorded human history has remained that bright for as long
as two months.
--
----------------------------------------------------------------
Paul Schlyter, Grev Turegatan 40, SE-114 38 Stockholm, SWEDEN
e-mail: pausch at stockholm dot bostream dot se
WWW: http://stjarnhimlen.se/
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Date: 23 Oct 2006 07:13:10
From: Paul Schlyter
Subject: Re: Any good memorable comets coming soon? Like Ikeya-Zhang Hale-Bopp
|
In article <1161547963.298583.243120@b28g2000cwb.googlegroups.com >,
CNJ999 <jbortle@aol.com > wrote:
> In point of fact, there hasn't been a "classic" Great Comet is 30
> years. While H-B and Hyakutake were in a sense rather spectacular, the
> brightness of either's tail (usually the most outstanding feature of a
> Great Comet)
.... I thought it was the length of the tail which mattered a lot for
a comet to be considered "great" ....
> were but pale representations of what nearly all of the Great Comets
> of the past have displayed.
....and there was always much more snow at Christmas in the past, and
the summers of the past were always much sunnier - right? :-)
I think we have two factors to consider here....
1. Selective memory: as time passes, we tend to remember only the best
of things we experienced, and to even make them a little better in
our memories than they actually were.
2. Light pollution getting more severe: in the past, light pollution
was less severe than today. At today's levels of light pollution,
even truly great comets appear pretty pale, unless you take the
trouble to travel to pristine skies - and few people do that.
> If we ever do get another truly Great Comet, I expect today's
> observers will be utterly shocked by its overall brilliance.
>
> The best time to have been an amateur astronomer interested in comets
> was between 1957 and 1976, when Great Comets were literally
> commonplace, with at least half a dozen appearing in the short span of
> just 20 years! In fact, it was the most prolific period for such
> objects in recorded history.
....could you please list those 6+ Great Comets which appeared during
these years? Of course they must, by your own definition above, be
bright enough and appear large enough to make both Hyakutake and
Hale-Bopp appear pale by comparison - this would require a 90+ degree
tail, and a magnitude approaching -5 WHEN THE COMET COULD BE SEEN IN
DARK SKIES well away from twilight. Any comet smaller or fainter than
that isn't likely to leave today's observers "utterly shocked", as you
phrased it above...
> The only similar grouping of truly
> briilliant comets took place about a century earlier than that and
> there are no other contenders for the title. So...as pointed out up
> stream...the typical historical odds for seeing a classical Great Comet
> are no better than perhaps 2 or 3 over the course of a lifetime. Thus,
> if you're wating for one...don't hold your breath!
>
> JBortle
I've seen a few of them: Bennett in 1970, Kohoutek in 1973-74 (don't
know if you count that one), and West in 1976. And of course also
Hyakutake in 1996 and Hale-Bopp in 1997. To me, the most impressive
of them all was Hyakutake, because if its tail length and also because
it appeared close to the zenith in a fully dark night sky. Yes, comet
West was definitely brighter, but when that bright, it could be
seen only fairly low in a sky which was starting to brighten from
morning twilight, and its tail didn't appear even nearly as long
as Hyakutake's....
Most great comets are great only briefly, and fade away quite quickly.
Here Hale-Bopp was an exception: it remained near magnitude zero (its
peak brightness) for two months! No other comet in recorded history
has remained that bright for so long. Several of my friends who
aren't star gazers and who missed Hyakutake completely, enjoyed
viewing Hale-Bopp, right from the middle of the city and its light
polluted skies.
Don't belittle Hyakutake and Hale-Bopp! Even though none of them
were the brightest comets of the century, they had other qualities,
and IMO they both qualify for being considered "Great Comets", just
as much as Bennett and West were!
--
----------------------------------------------------------------
Paul Schlyter, Grev Turegatan 40, SE-114 38 Stockholm, SWEDEN
e-mail: pausch at stockholm dot bostream dot se
WWW: http://stjarnhimlen.se/
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Date: 23 Oct 2006 10:21:43
From: Willie R. Meghar
Subject: Re: Any good memorable comets coming soon? Like Ikeya-Zhang Hale-Bopp
|
Some general comments for the original poster, who's posting I managed
to prematurely delete:
A "good memorable comet" could show up a few weeks from now, a few
decades from now, or at any time in between; but be forewarned: Most
comets are best seen from a *dark* sky! Some comets pass by so
quickly that a few cloudy nights can make the difference between
seeing a 90 degree tail or a *much* shorter tail. Furthermore, If you
happen to be at the wrong geographic location when a "good memorable
comet" passes by you could miss the comet entirely -- clear, dark sky
or not!
To make the best of any "good memorable comets" that happen by, it's a
good idea to spend some time observing any and all visible comets.
For some people Comet SWAN, currently visible in the northwestern,
evening sky might qualify as a "good memorable comet." I've grown
kind of fond of this little visiter . . .
I've not yet checked out the new Comet Levy, currently in the morning
sky -- even though I had observed Saturn just a few mornings before
David Levy discovered his latest comet -- near Saturn! (. . . and I
used to hunt comets! Just writing this is giving me second thoughts
on my long neglected comet hunting program . . .)
P.S. Comet tails tend to be fainter in real life (to the human eye)
than they are usually depicted in drawings, paintings, or (especially)
photographs. Photographic details within comet tails are often not
seen visually. Observing currently visible comets (on a continuing
basis) will help in the appreciation of the "really good ones!"
Willie R. Meghar
Observational Notes at:
http://meghar.blogspot.com/
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Date: 23 Oct 2006 22:29:05
From: David Knisely
Subject: Re: Any good memorable comets coming soon? Like Ikeya-Zhang Hale-Bopp
|
Since there is no commmonly agreed-upon definition for a "great" comet,
any dismissive argument on which comet does not deserve to be called
"great" is a bit dubious at best. Donald Yeomans even stated:
" > applying the appellation "great comet" to a particular cometary
return is a subjective process,
However, he does list at least *some* which he would tend to call "great"
http://ssd.jpl.nasa.gov/?great_comets
In the time frame of the late 1950's to the present, Yeomans lists
Comets Ikeya-Seki, Bennett, West, Hyakutake, and Hale-Bopp, although I
also might add that Arend-Roland should probably be in this group as
well. I would definitely not call Kohoutek a "great" comet, as at least
from my vantage point (good, yes, but great, probably not). It was
quite pretty and easy to view, but wasn't all that spectacular, at least
from 40 degrees north. West was probably the most impressive of those I
have personally seen, as it was nice and bright with a prominent
multi-component tail that was easily visible from my 9th floor UNL
dormatory room inside a city of 180,000 people. I think any comet which
is fairly easily seen and *noticed* by the general public probably
deserves to be called "great", so I would tend to put Hale-Bopp and
Hyakutake in the "great" class. Both generated huge lines of people at
Hyde Observatory even when we hadn't advertised that we would be
observing the comets.
Although the following is still somewhat subjective, I might use four
classes of comets based on their visual appearance:
1. Telescopic comets: those not visible without a telescope.
Examples: too numerous to mention.
2. Binocular comets: those visible with a simple pair of binoculars or
occasionally marginally seen with the unaided eye from a dark sky site.
Examples: Comet Swan, and lots of others.
3. Naked-eye comets: those fairly easily seen without optical aid from
either a dark sky site or a mildly light-polluted site.
Examples: Kohoutek, IRAS-Araki-Alcott, Halley (last apparition),
Bradfield (C/2004 F4), etc. Some of these "flirt" with greatness
briefly and may become fairly well-observed by many amateurs, but often
go unnoticed by the public.
4. Great Comets: spectacular visual objects (probably brighter than 1st
magnitude) which are easily visible even under somewhat less than ideal
conditions, and which can show an easily noticable tail structure to the
unaided eye.
Examples: Ikeya-Seki, West, Hyakutake, Hale-Bopp, etc.
Clear skies to you.
--
David W. Knisely KA0CZC@navix.net
Prairie Astronomy Club: http://www.prairieastronomyclub.org
Hyde Memorial Observatory: http://www.hydeobservatory.info/
**********************************************
* Attend the 13th Annual NEBRASKA STAR PARTY *
* July 23-28, 2006, Merritt Reservoir *
* http://www.NebraskaStarParty.org *
**********************************************
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Date: 24 Oct 2006 11:37:12
From: Greg Crinklaw
Subject: Re: Any good memorable comets coming soon? Like Ikeya-Zhang Hale-Bopp
|
The problem is this: it's perfectly alright to say, "comet X was a great
comet to me because..." because "great" is entirely subjective. Sure,
some people put numbers on it, but that doesn't make their scale any
less subjective. After all some people look at the magnitude and other
look at how many people saw or spoke about a "great" comet. Both are
equally subjective.
What really rubs people the wrong way is the reverse: stating "x comet
was not great." One could get away with, "x comet was not great to me."
But to try to claim some absolute standard is absurd, full of hubris,
and ultimately disrespectful of those who feel comet x was great for
their own reasons.
That is why, John, you get such a big argument here on SAA every time
you state which comets are great and, more importantly, which weren't.
You leave out that one little but essential part that the rest of us
include: "to me."
Some comets I personally think were "Wonderful:" (alphabetically ;-))
de Vico
Hale-Bopp
Halley
Hyakutake
IRAS-Araki-Alcock
Shoemaker-Levy-9
Each of these was memorable to me for some personal reason. Is not the
love of comets something personal--something that goes far beyond mere
measures of magnitude or tail length? If comets truly are like cats,
why would we choose to rank them by how long their tails are rather than
how often they sit in our lap?
The whole idea of categorizing them neatly and then arguing about which
was better seems to me to be missing the point.
Clear skies,
Greg
--
Greg Crinklaw
Astronomical Software Developer
Cloudcroft, New Mexico, USA (33N, 106W, 2700m)
SkyTools: http://www.skyhound.com/cs.html
Observing: http://www.skyhound.com/sh/skyhound.html
Comets: http://www.skyhound.com/sh/comets.html
To reply take out your eye
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Date: 28 Oct 2006 09:40:18
From:
Subject: Re: Any good memorable comets coming soon? Like Ikeya-Zhang Hale-Bopp
|
CNJ999 wrote:
> Paul - Regarding you comments, there is nothing subjective about my
> statement. To the average amateur astronomer who saw H-B or Hyakutake,
> from a typical observing site, many comets of the past were far more
> spectacular in overall impressiveness.
> Any of these first 5 or 6 most any observer today would placed well
> above H-B or Hyakutake if they had a chance to compare them side by
> side. Just because you or those today have never seen objects of such
> grandeur, don't think they are products of a hazy memory. You'll be
> convinced when a really good one comes along again.
>
> JBortle
You seem to be inconsistant with your own opinions (unless this isn't
you).
http://groups.google.com/group/sci.astro.amateur/browse_thread/thread/d6e9fe07f6a52033/3325c3288309bb15?lnk=gst&q=jbortle+great+comets&rnum=3#3325c3288309bb15
http://groups.google.com/group/sci.astro.amateur/browse_thread/thread/1f0dfed751ea8de4/070b50e9295ec1ba?lnk=gst&q=jbortle+great+comets&rnum=15#070b50e9295ec1ba
If the links don't appear properly search this group for "jbortle great
comets". I don't have any opinion myself since I didn't see any of
those older comets.
Alvan Clark
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Date: 28 Oct 2006 13:52:13
From: CNJ999
Subject: Re: Any good memorable comets coming soon? Like Ikeya-Zhang Hale-Bopp
|
On 28, 4:19=A0pm, David Knisely <KA0...@navix.net > wrote:
> J. Bortle wrote:
> > Indeed, I saw Hyakutake on a number of nights from a site with
> > excellent sky conditions and could trace the tail 70 degrees
> > (incidentally, the reported 100+ degree tails were nonsense and
> > physically quite impossible under the circumstances). However, that
> > comet's tail was of quite low surface brightnes and the typical amateur
> > report credited it with a length of more like 10-15 degrees and very
> > faint at that. Likewise, while H-B did have a nice bright coma, except
> > for the first few dgrees, its tail was generally of low surface
> > brightness as well and relatively few amateurs saw more than ten
> > degrees or so in its span.Impossible? =A0Well, only if the tail was com=
pletely straight (and there
> was no subtle dust tail contribution which might have been seen about
> the time of closest approach to Earth). =A0There have been some arguments
> about maximum tail length, but I believe that some analysis published in
> Sky and Telescope at one time showed that it was possible for some
> mechanism (other than pure geometry) to produce an observed tail length
> of more than 90 degrees. =A0As for the visual appearance, I did see a tail
> length than definitely exceeded 60 degrees, although the tail was not as
> bright as those of Hale-Bopp's or West's. =A0I had a little difficulty
> with getting a maximum tail length estimate at one time, as the tail
> entered the Gegenschein as seen from my dark sky site. =A0Hyakutake showed
> a 25 degree long tail which was faint but easily seen by the public at
> Hyde Observatory on a night (March 26th, 1996) when the first quarter
> moon was in the sky (and this is in a park inside a city of nearly
> 200,000). =A0This, at least in my book, does qualify Comet Hyakutake to be
> considered a "great" comet. =A0Clear skies to you.
> --
Yes, quite impossible. To have exceeded 70-75 or so degrees would have
required physical circumstance/properties never observed in the history
of cometary astronomy in any other comet. This was likewise true
regarding some of the late April observations, when a very long tail
continued to be reported by a few individuals. The question has been
addressed in several published papers.
The only supposed validation of the 90-120 degree reported tail at the
comet's pre-T perigee was based solely on a detection of cometary tail
particles long after perihelion passage by a spacecraft. Even then, it
was never demonstarted that the particle density/cross section detected
was anything like akin to that necessary to have been visually
detectable at any significant celestial distance. Further, the tail
curvature indicated by the spacecraft data was ONLY valid for the
post-T phase of the comet's apparition, when the outer portion of the
tail(s) would have normally been expected to be highly curved as a
result of the comet's tight orbital path around perihelion.
I have never contended that Comet Hyakutake was not to be classed among
Great Comets but rather that, in particular, the intensity of its tail
(as well as H-B's) and general impressiveness was, for most, 2nd rate
as Great Comets when comparing the two recent objects with the displays
put on by many past Great Comets. So, I have to say again that
observers are going to be shocked to see what a classical Great Comet
looks like when one finally appears, cause they ain't seen nothing yet.
JBortle
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Date: 22 Oct 2006 10:40:12
From:
Subject: Re: Any good memorable comets coming soon? Like Ikeya-Zhang Hale-Bopp
|
Chris L Peterson wrote:
> On Sun, 22 2006 16:53:23 GMT, David Nakamoto
> <david.nakamoto@verizon.net> wrote:
>
> >Truthfully, play the lottery; your chances of hitting the big times with
> >the Lottery are about as good as what the chances are for the next great
> >comet.
>
> Or not. Most people can expect to see one or two great naked eye comets
> in their lifetime. But even if you played the lottery every day, you'll
> need many lifetimes to have a significant chance of "hitting the big
> times".
>
> Granted, there is some looseness as to what constitutes a "great" comet.
> I clearly recall three I'd place in that category: West, Hyakutake, and
> Hale-Bopp. And I recall another half-dozen or so naked eye comets that
> were bright enough to see a tail- all of which were spectacular in
> binoculars ("almost great"? "real good?"). And all of those in less than
> 30 years. Better than my lottery record!
>
I'd throw in IRAS-Araki-Alcock (1983) if only because it passed so
close to Earth and moved very rapidly across the sky. It was easy to
see with the unaided eye under darker skies, but invisible under light
polluted skies.
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Date: 22 Oct 2006 19:51:04
From: George Normandin
Subject: Re: Any good memorable comets coming soon? Like Ikeya-Zhang Hale-Bopp
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< > wrote
> ............
> I'd throw in IRAS-Araki-Alcock (1983) if only because it passed so
> close to Earth and moved very rapidly across the sky. It was easy to
> see with the unaided eye under darker skies, but invisible under light
> polluted skies.
Ya! I would add that comet to Chris's list, even though I only observed
it on one night. It was certainly 'naked eye' even from a small city (looked
like a little cloud - no tail) and with 7x50 binocs you could see movement
against the background stars.
George N
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Date: 23 Oct 2006 18:10:21
From: canopus56
Subject: Re: Any good memorable comets coming soon? Like Ikeya-Zhang Hale-Bopp
|
canopus56 wrote:
> canopus56 wrote:
<snip >
> If you limit your definition of a "great comet" to more than magnitude
> 4,. . .
should read: more than magnitude -4
Canopus56
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Date: 23 Oct 2006 18:07:23
From: canopus56
Subject: Re: Any good memorable comets coming soon? Like Ikeya-Zhang Hale-Bopp
|
canopus56 wrote:
> Is there a chart somewhere on the net with would graphically shows the
> number and/or magnitudes of observable comets by year - so I could get
> a feel for the great comet windows? - Canopus56
This ICQ page lists 40 comets of maximum apparent naked-eye Earth
observed brightness greater than mag 4 between 1935 and part of 2005 (a
69 year interval).
http://cfa-www.harvard.edu/icq/brightest.html
The ICQ page states that:
"One can see from this that, on average, we are able to view a comet
that is brighter than fourth magnitude once every two years, a comet
brighter than second mag once every 5.5 years or so, a comet brighter
than first magnitude every 10 years or so, and a comet brighter than
mag 0 roughly once every 15 years; of course, sometimes there will be
two bright comets in a span of a year, while at other times there will
be a 20-year interval between such apparitions. [updated 2005 Sept.
14]"
>From that list, I prepared the following frequency table -
Mag Interval N Per/yr Freq - once in x years
<-4 2 0.03 34.5
-3.9 to -2.5 4 0.06 17.3
-2.4 to -1 3 0.04 23.0
-0.96 to 0.5 6 0.09 11.5
0.6 to 2.5 7 0.10 9.9
2.6 to 4 18 0.26 3.8
- which is shown graphically as follows:
Distribution by time
http://members.csolutions.net/fisherka/astronote/notes/20061023Cometbrightness1935_2005.jpg
Count per magnitude
http://members.csolutions.net/fisherka/astronote/notes/20061023Cometfrequencybrightness69years.jpg
Probability of occurrence - frequency once in x years
http://members.csolutions.net/fisherka/astronote/notes/20061023CometfrequencybrightnessOccurrence.jpg
If you limit your definition of a "great comet" to more than magnitude
4, then there is a heyday in the mid-20th century. But the 21st century
is still young!
- Canopus56
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Date: 23 Oct 2006 10:37:12
From: canopus56
Subject: Re: Any good memorable comets coming soon? Like Ikeya-Zhang Hale-Bopp
|
CNJ999 wrote:
<snip >
> The best time to have been an amateur astronomer interested in comets
> was between 1957 and 1976, when Great Comets were literally
> commonplace, with at least half a dozen appearing in the short span of
> just 20 years! In fact, it was the most prolific period for such
> objects in recorded history
Is there a chart somewhere on the net with would graphically shows the
number and/or magnitudes of observable comets by year - so I could get
a feel for the great comet windows? - Canopus56
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Date: 24 Oct 2006 09:21:57
From: canopus56
Subject: Re: Any good memorable comets coming soon? Like Ikeya-Zhang Hale-Bopp
|
CNJ999 wrote:
> On 23, 9:07?pm, "canopus56" <canopu...@yahoo.com> wrote:
> > canopus56 wrote:
<snip >
> It is interesting to note thae even in this supposedly authorative
> source the order of listing is highly questionable.
Combining the two lists -
ICQ
http://cfa-www.harvard.edu/icq/brightest.html
Yeomans
http://ssd.jpl.nasa.gov/?great_comets
- I get a total of 31 great comets on the criteria of brighter than
magnitude 1 between 1618 and 2006.
That works out to a frequency of once every 12.5 years. This may
underestimate the frequency of great brighter than magnitude 1 since
the observations that Yeoman's list is based on is northern hemisphere
Eurocentric. I understand that there are no reliable reports for
comets that may reached their brightest while in the southern
hemisphere. I haven't plotted them in time to look for clumping
effects.
The quick search of the S&T magazine articles turns up a reference to a
book review:
Great Comets, by Robert Burnham
Carolyn Collins Petersen; Sky & Telescope (Archives); 2001; 69;
and one of your articles:
Cometography: A Catelog of Comets, Vol. 1, by Gary W. Kronk
John E Bortle; Sky & Telescope (Archives); May 2000; 76;
- Canopus56
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Date: 24 Oct 2006 07:52:03
From: CNJ999
Subject: Re: Any good memorable comets coming soon? Like Ikeya-Zhang Hale-Bopp
|
On 24, 10:11=A0am, "CNJ999" <jbor...@aol.com > wrote:
> On 23, 11:29?pm, David Knisely <KA0...@navix.net> wrote:
>
> > Since there is no commmonly agreed-upon definition for a "great" comet,
> > any dismissive argument on which comet does not deserve to be called
> > "great" is a bit dubious at best. ?Donald Yeomans even stated:
> > ? "> applying the appellation "great comet" to a particular cometary
> > return is a subjective process,
>
> > However, he does list at least *some* which he would tend to call "grea=
t"
>
> >http://ssd.jpl.nasa.gov/?great_cometsWhat's absolutely absolutely amazin=
g about Don's list is that every
> single maximum reported magnitude in this compilation, with the
> exception of that for H-B, is widely inaccurate!
>
This should have read,"...every single maximum magnitude in this
compilation for 20th century comets, with the exception of that for
H-B, is widely inaccurate."=20
JBortle
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Date: 24 Oct 2006 15:30:19
From: David Knisely
Subject: Re: Any good memorable comets coming soon? Like Ikeya-Zhang Hale-Bopp
|
J. Bortle wrote:
>>On 23, 11:29?pm, David Knisely <KA0...@navix.net> wrote:
>>>
>>
>>>> > Since there is no commmonly agreed-upon definition for a "great" comet,
>>>> > any dismissive argument on which comet does not deserve to be called
>>>> > "great" is a bit dubious at best. ?Donald Yeomans even stated:
>>>> > ? "> applying the appellation "great comet" to a particular cometary
>>>> > return is a subjective process,
>>
>>>
>>
>>>> > However, he does list at least *some* which he would tend to call "great"
>>
>>>
>>
>>>> >http://ssd.jpl.nasa.gov/?great_cometsWhat's absolutely absolutely amazing about Don's list is that every
>>
>>> single maximum reported magnitude in this compilation, with the
>>> exception of that for H-B, is widely inaccurate!
>>>
>
>
> This should have read,"...every single maximum magnitude in this
> compilation for 20th century comets, with the exception of that for
> H-B, is widely inaccurate."
>
> JBortle
>
Well, clearly, you didn't actually read the article all that well. The
figure Donald Yeomans gives is *not* the peak brightness! In the second
paragraph, Donald states:
"The following columns give the date and distance when the comet reached
its closest point to the Earth (perigee), and the date and apparent
magnitude when the comet reached its brightest in a dark sky. A diffuse
cometary image becomes noticeable to the naked eye when it reaches a
magnitude of approximately 3.4 in a dark sky."
Note the words *"in a dark sky"* which are used twice. It was the
brightest the comet appeared when it was visible in a dark sky and not
during heavy twilight or during the daytime. The number he gives will
thus *only* be a rough estimate rather than an exact figure. Indeed, it
is a somewhat useful one, as it does not overstate the overall visual
effect of the comet, as might happen if one used the maximum brightness
figure alone.
Ikeya-Seki's "maximum" brightness estimate provided by Yeomans is, of
course, somewhat off of its maximum (estimates I have seen placed its
maximum magnitude in the -7 to -10 range). However, except for its
brief daylight visiblity magnitude "spike", it was significantly fainter
than this, and this is apparently what Don is referring to. Bennett's
maximum estimate of 0-1 isn't all that far off (0.5 according to Kronk),
considering that estimates of maximum comet brightness are often not all
that exact and depend to some extent on who was making the observations.
Comet West's figure might have seemed a bit on the low side, although
again, like Ikeya-Seki, the maximum brightness (-3) mainly occurred when
the comet was fairly close to the sun and not in a nice dark sky. When
I first saw it with its magnificent tail in a dark sky before dawn, it
was probably close to -1. I could see its yellowish color quite well,
and followed it with my unaided eye from my dorm room until only about
15 minutes before sunrise. However, the comet did fade fairly rapidly as
the days went by. Comet Hyakutake's figure of 1-2 is indeed just a bit
low, but again, the estimates varied somewhat. Zero magnitude seemed to
be a somewhat common figure for its maximum brightness, and looking back
on my own observations, I gave it that figure for my observations of
March 24th and 26th of 1996.
However, this all is somewhat irrelevant. Whatever the magnitude
"estimates" provded are, Yeoman's listing does contain a number of
comets which could easily be considered as "great". Clear skies to you.
--
David W. Knisely KA0CZC@navix.net
Prairie Astronomy Club: http://www.prairieastronomyclub.org
Hyde Memorial Observatory: http://www.hydeobservatory.info/
**********************************************
* Attend the 13th Annual NEBRASKA STAR PARTY *
* July 23-28, 2006, Merritt Reservoir *
* http://www.NebraskaStarParty.org *
**********************************************
|
| | |
Date: 29 Oct 2006 09:42:40
From: Paul Schlyter
Subject: Re: Any good memorable comets coming soon? Like Ikeya-Zhang Hale-Bopp
|
In article <1161701523.258370.162490@m73g2000cwd.googlegroups.com >,
CNJ999 <jbortle@aol.com > wrote:
> On 24, 10:11=A0am, "CNJ999" <jbor...@aol.com> wrote:
>> On 23, 11:29?pm, David Knisely <KA0...@navix.net> wrote:
>>
>>> Since there is no commmonly agreed-upon definition for a "great" comet,
>>> any dismissive argument on which comet does not deserve to be called
>>> "great" is a bit dubious at best. ?Donald Yeomans even stated:
>>> ? "> applying the appellation "great comet" to a particular cometary
>>> return is a subjective process,
>>
>>> However, he does list at least *some* which he would tend to call
>>> "great"
>>
>>> http://ssd.jpl.nasa.gov/?great_cometsWhat's absolutely absolutely
>>> amazing about Don's list is that every single maximum reported magnitude
>>> in this compilation, with the exception of that for H-B, is widely
>>> inaccurate!
>
> This should have read,"...every single maximum magnitude in this
> compilation for 20th century comets, with the exception of that for
> H-B, is widely inaccurate."
>
> JBortle
...and that's a claim from someone (you) who says that 5 is "at least
half a dozen" .... <g >
Very well, what peak magnitude would you want to give to Comet Hyakutake?
You claimed the peak magnitude in that list was "wildly inaccurate", so
you must have some idea of what you think it should have been instead?
--
----------------------------------------------------------------
Paul Schlyter, Grev Turegatan 40, SE-114 38 Stockholm, SWEDEN
e-mail: pausch at stockholm dot bostream dot se
WWW: http://stjarnhimlen.se/
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Date: 29 Oct 2006 12:44:57
From: David Knisely
Subject: Re: Any good memorable comets coming soon? Like Ikeya-Zhang Hale-Bopp
|
Paul Schlyter posted:
> ...and that's a claim from someone (you) who says that 5 is "at least
> half a dozen" .... <g>
>
> Very well, what peak magnitude would you want to give to Comet Hyakutake?
> You claimed the peak magnitude in that list was "wildly inaccurate", so
> you must have some idea of what you think it should have been instead?
John didn't read Yeomans' article all that well, so he took the
magnitudes listed in the table as those for the maximum "peak" magnitude
the comet had during its entire apparition, rather than the "magnitude
in a dark sky" which Yeomans had intended. Clear skies to you.
--
David W. Knisely KA0CZC@navix.net
Prairie Astronomy Club: http://www.prairieastronomyclub.org
Hyde Memorial Observatory: http://www.hydeobservatory.info/
**********************************************
* Attend the 13th Annual NEBRASKA STAR PARTY *
* July 23-28, 2006, Merritt Reservoir *
* http://www.NebraskaStarParty.org *
**********************************************
|
| |
Date: 24 Oct 2006 07:11:33
From: CNJ999
Subject: Re: Any good memorable comets coming soon? Like Ikeya-Zhang Hale-Bopp
|
On 23, 11:29=A0pm, David Knisely <KA0...@navix.net > wrote:
> Since there is no commmonly agreed-upon definition for a "great" comet,
> any dismissive argument on which comet does not deserve to be called
> "great" is a bit dubious at best. =A0Donald Yeomans even stated:
> =A0 "> applying the appellation "great comet" to a particular cometary
> return is a subjective process,
>
> However, he does list at least *some* which he would tend to call "great"
>
> http://ssd.jpl.nasa.gov/?great_comets
>
What's absolutely absolutely amazing about Don's list is that every
single maximum reported magnitude in this compilation, with the
exception of that for H-B, is widely inaccurate!
JBortle
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Date: 24 Oct 2006 06:45:36
From: CNJ999
Subject: Re: Any good memorable comets coming soon? Like Ikeya-Zhang Hale-Bopp
|
On 23, 9:07=A0pm, "canopus56" <canopu...@yahoo.com > wrote:
> canopus56 wrote:
> > Is there a chart somewhere on the net with would graphically shows the
> > number and/or =A0magnitudes of observable comets by year - so I could g=
et
> > a feel for the great comet windows? =A0- Canopus56This ICQ page lists 4=
0 comets of maximum apparent naked-eye Earth
> observed brightness greater than mag 4 between 1935 and part of 2005 (a
> 69 year interval).
>
> http://cfa-www.harvard.edu/icq/brightest.html
>
It is interesting to note thae even in this supposedly authorative
source the order of listing is highly questionable. I note that the
Great Southern Comet of 1947 is listed as attaining -4. However, this
is based on a single, highly subjective statement in the literature
that it, "looked like Venus seen through clouds", not on any actual
comparison with other bright stars or planets. Other initially reported
values for this comet were around 0 magnitude. On the other hand, the
Eclipse Comet of 1948 was, at discovery during a total solar eclipse in
Egypt, said to be brighter than any star or planet (-2?)." Likewise,
the first post-perihelion sighting of Comet Seki-Line, made by a very
experienced comet observer in England, indicated it as at least of -2.5
and later he thought he had even underestimated the total magnitude
then! There are other inconsistancies in the list as well.
At one time I had a cataolg or listing of all the comets brighter than
magnitude +2.5 seen during the past 200 years posted on Charles Morris'
JPL Comet Home Page. Each entry included a thumbnail description of the
apparition, including the reported peak magnitude, tail length and
duration. Unfortunately, this site changed locations and its
replacement is no longer active.
JBortle
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| | |
Date: 29 Oct 2006 09:42:40
From: Paul Schlyter
Subject: Re: Any good memorable comets coming soon? Like Ikeya-Zhang Hale-Bopp
|
In article <1161697536.401322.207390@h48g2000cwc.googlegroups.com >,
CNJ999 <jbortle@aol.com > wrote:
> At one time I had a cataolg or listing of all the comets brighter than
> magnitude +2.5 seen during the past 200 years posted on Charles Morris'
> JPL Comet Home Page. Each entry included a thumbnail description of the
> apparition, including the reported peak magnitude, tail length and
> duration. Unfortunately, this site changed locations and its
> replacement is no longer active.
Did you try to find it at http://web.archive.org ??? That sites allow
you to "revive" a lot of old sites which have vanished, and there you'll
probably find that list. Or you could post the (now outdated) URL to that
old site so anyone here could try to find it at http://Web.archive.org
--
----------------------------------------------------------------
Paul Schlyter, Grev Turegatan 40, SE-114 38 Stockholm, SWEDEN
e-mail: pausch at stockholm dot bostream dot se
WWW: http://stjarnhimlen.se/
|
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Date: 24 Oct 2006 03:49:53
From:
Subject: Re: Any good memorable comets coming soon? Like Ikeya-Zhang Hale-Bopp
|
Then of course there was Comet Shoemaker-Levy 9, which fits into class
1(described below,) but which generated quite a bit of interest
nonetheless. :-)
David Knisely wrote:
> Since there is no commmonly agreed-upon definition for a "great" comet,
> any dismissive argument on which comet does not deserve to be called
> "great" is a bit dubious at best. Donald Yeomans even stated:
> "> applying the appellation "great comet" to a particular cometary
> return is a subjective process,
>
> However, he does list at least *some* which he would tend to call "great"
>
> http://ssd.jpl.nasa.gov/?great_comets
>
> In the time frame of the late 1950's to the present, Yeomans lists
> Comets Ikeya-Seki, Bennett, West, Hyakutake, and Hale-Bopp, although I
> also might add that Arend-Roland should probably be in this group as
> well. I would definitely not call Kohoutek a "great" comet, as at least
> from my vantage point (good, yes, but great, probably not). It was
> quite pretty and easy to view, but wasn't all that spectacular, at least
> from 40 degrees north. West was probably the most impressive of those I
> have personally seen, as it was nice and bright with a prominent
> multi-component tail that was easily visible from my 9th floor UNL
> dormatory room inside a city of 180,000 people. I think any comet which
> is fairly easily seen and *noticed* by the general public probably
> deserves to be called "great", so I would tend to put Hale-Bopp and
> Hyakutake in the "great" class. Both generated huge lines of people at
> Hyde Observatory even when we hadn't advertised that we would be
> observing the comets.
>
> Although the following is still somewhat subjective, I might use four
> classes of comets based on their visual appearance:
>
> 1. Telescopic comets: those not visible without a telescope.
> Examples: too numerous to mention.
>
> 2. Binocular comets: those visible with a simple pair of binoculars or
> occasionally marginally seen with the unaided eye from a dark sky site.
> Examples: Comet Swan, and lots of others.
>
> 3. Naked-eye comets: those fairly easily seen without optical aid from
> either a dark sky site or a mildly light-polluted site.
> Examples: Kohoutek, IRAS-Araki-Alcott, Halley (last apparition),
> Bradfield (C/2004 F4), etc. Some of these "flirt" with greatness
> briefly and may become fairly well-observed by many amateurs, but often
> go unnoticed by the public.
>
> 4. Great Comets: spectacular visual objects (probably brighter than 1st
> magnitude) which are easily visible even under somewhat less than ideal
> conditions, and which can show an easily noticable tail structure to the
> unaided eye.
> Examples: Ikeya-Seki, West, Hyakutake, Hale-Bopp, etc.
>
> Clear skies to you.
> --
> David W. Knisely KA0CZC@navix.net
> Prairie Astronomy Club: http://www.prairieastronomyclub.org
> Hyde Memorial Observatory: http://www.hydeobservatory.info/
>
> **********************************************
> * Attend the 13th Annual NEBRASKA STAR PARTY *
> * July 23-28, 2006, Merritt Reservoir *
> * http://www.NebraskaStarParty.org *
> **********************************************
|
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Date: 24 Oct 2006 17:25:25
From: canopus56
Subject: Re: Any good memorable comets coming soon? Like Ikeya-Zhang Hale-Bopp
|
X-No-archive: yes
CNJ999 wrote:
> As I said earlier, my web article, that was included on the JPL Comet
> Home Page, was the most inclusive, accurate yet brief, on-line listing
> to be found regarding the appearance of all the bright comets of the
> past two centuries. I really need to see about getting that posted
> again...maybe on the ICQ site?
Thanks, John - C.
|
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Date: 24 Oct 2006 15:51:54
From: CNJ999
Subject: Re: Any good memorable comets coming soon? Like Ikeya-Zhang Hale-Bopp
|
On 24, 3:11=A0pm, "canopus56" <canopu...@yahoo.com > wrote:
> CNJ999 wrote:
> > It is interesting to note thae even in this supposedly authorative
> > source the order of listing is highly questionable.John, =A0which of yo=
ur two articles would have the most authoritative
> list? =A0I'd like to go pull one off the shelf.
>
> Bortle, John E. Jan. 1997. Great Comets in History. S&T 93(1):44
>
> Bortle, John E. May 1990. =A0An Observer's Guide to Great Comets . S&T
> 79:491
>
> - Canopus56
Both are interesting pieces but the former is the one that includes
descriptions of a selection (by no means a complete list) of Great
Comets.
As I said earlier, my web article, that was included on the JPL Comet
Home Page, was the most inclusive, accurate yet brief, on-line listing
to be found regarding the appearance of all the bright comets of the
past two centuries. I really need to see about getting that posted
again...maybe on the ICQ site?
JBortle
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Date: 24 Oct 2006 15:16:00
From: CNJ999
Subject: Re: Any good memorable comets coming soon? Like Ikeya-Zhang Hale-Bopp
|
On 24, 4:30=A0pm, David Knisely <KA0...@navix.net > wrote:
> > JBortleWell, clearly, you didn't actually read the article all that wel=
l=2E =A0The
> figure Donald Yeomans gives is *not* the peak brightness! =A0In the second
> paragraph, Donald states:
>
> "The following columns give the date and distance when the comet reached
> its closest point to the Earth (perigee), and the date and apparent
> magnitude when the comet reached its brightest in a dark sky.
You are correct, David. In glancing through Don's piece before posting,
I missed his qualifier. However, employing such a limitation is quite
misleading and doesn't do justice to many of the truly Great Comets,
since a large portion of their individual fame was often tied to their
being visible under special circumstances, like visibility in daylight.
Don even ignored his own rule to include Comet Skjellerup of 1927...a
daylight comet (max. mag. -6) that was never visible, when of any
significant brightness, outside of bright twilight. Such qualifiers
blur the line between spectacular comets and rather common, simply
bright, ones. It allows no real sense of which ones were really in the
class of Great Comets and which were not.
JBortle
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Date: 25 Oct 2006 00:13:50
From: David Knisely
Subject: Re: Any good memorable comets coming soon? Like Ikeya-Zhang Hale-Bopp
|
J. Bortle wrote:
> Don even ignored his own rule to include Comet Skjellerup of 1927...a
> daylight comet (max. mag. -6) that was never visible, when of any
> significant brightness, outside of bright twilight.
What rule is that? As far as I can tell, Yeomans never states any
explicit rule(s) for determining what is a "great" comet. He only says
that, "A diffuse cometary image becomes noticeable to the naked eye when
it reaches a magnitude of approximately 3.4 in a dark sky", which is a
mere statement of fact. He never says that this is the "rule" he is
going to use exclusively when deciding what is (or more importantly,
what is not) a "great" comet. Indeed, brightness is only one aspect of
what may make a comet "great". Clearly, tail length figures prominently
in Yeomans' judgment of what constitutes a "great" comet, as tail length
is mentioned a number of times in the notes for many of his footnoted
examples. Comet Skjellerup-Maristany when out of the twilight had an
impressive tail that was estimated to be up to 40 degrees in length for
several days in late December and early January, with a brightness of
around 3rd magnitude on December 21st, although the comet was fading
rapidly. Comet Ikeya-Seki did a similar rapid post-perhelion fade,
eventually almost becoming a "tail without a comet", due to the
faintness of the head after perhelion.
If a comet is unusually noticable with the unaided eye and has a
prominent tail, then it probably is worthy of at least consideration of
being put in the "great" class. One could set a minimum tail length, a
maximum brightness magnitude, or a combination of the two factors to
determmine which deserve to be called "great" comets, but this has never
been done in a systematic manner, nor is it likely that many people
will agree on the exact methods of doing so. The fact remains that
there simply is no well-defined or agreed-upon definition for a comet to
be considered "great". Clear skies to you.
--
David W. Knisely KA0CZC@navix.net
Prairie Astronomy Club: http://www.prairieastronomyclub.org
Hyde Memorial Observatory: http://www.hydeobservatory.info/
**********************************************
* Attend the 13th Annual NEBRASKA STAR PARTY *
* July 23-28, 2006, Merritt Reservoir *
* http://www.NebraskaStarParty.org *
**********************************************
|
| |
Date: 24 Oct 2006 12:11:12
From: canopus56
Subject: Re: Any good memorable comets coming soon? Like Ikeya-Zhang Hale-Bopp
|
CNJ999 wrote:
> It is interesting to note thae even in this supposedly authorative
> source the order of listing is highly questionable.
John, which of your two articles would have the most authoritative
list? I'd like to go pull one off the shelf.
Bortle, John E. Jan. 1997. Great Comets in History. S&T 93(1):44
Bortle, John E. May 1990. An Observer's Guide to Great Comets . S&T
79:491
- Canopus56
|
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Date: 24 Oct 2006 12:01:52
From: canopus56
Subject: Re: Any good memorable comets coming soon? Like Ikeya-Zhang Hale-Bopp
|
canopus56 wrote:
<snip all >
Here's a distribution based on ICQ and Yeoman (1998) for comets
brighter than mag 1 (excluding C1965 S1) between 1618 and 2005 (387
years):
Mag N Per/yr Once in x years
< -3 4 0.01 96.8
0 to -3 15 0.04 25.8
1 to 0 10 0.03 38.7
Plus C/1965 S1 gives a total of 30 in 387 years or once every 12.9
years brighter than mag 1.
Graphs - Distribution in time:
http://members.csolutions.net/fisherka/astronote/notes/20061023Cometfrequencybrightness1618_2005.jpg
(Note the "gap" between 1686 and 1769)
- Canopus56
P.S. - Definitely better odds to see a great comet than winning the
Idaho Powerball lotto (1:400,000 or once every 400,000 years). -:)
|
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Date: 24 Oct 2006 11:09:03
From: canopus56
Subject: Re: Any good memorable comets coming soon? Like Ikeya-Zhang Hale-Bopp
|
Greg Crinklaw wrote:
> The problem is this: it's perfectly alright to say, "comet X was a great
> comet to me because..." because "great" is entirely subjective. Sure,
> some people put numbers on it, but that doesn't make their scale any
> less subjective.
Granted there is a classification problem, e.g. - like the C/1965 S1
Ikeya-Seki on your site:
http://cometography.com/lcomets/1965s1.html
verses the dimmer C/1996 Hyakutake -
http://zebu.uoregon.edu/cometh/
But the top-poster's simple question is not beyond reach of being
roughly quantified. Using Yeoman's lists and a criteria of an
unqualified magnitude 0 or greater gives 8 comets in 388 years or one
about every 48.5. That is near Chris Peterson's estimate of once every
forty years. So -
- Once every 35 to 50 years for a real heart stopping naked-eye comet.
- Once in 15 to 17 years for a good to nearly great -2.5 mag comet
- Once every 11.5 years for a "pretty good" 0.5 to -1 comet
- Once in every 10 years for a "good" 2.5 to 0.5 comet
- Canopus56
P.S. - The way Yeoman's list present is unclear. Does "0-1" mean 0 to
1 mags or 0 or -1 mags?
|
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Date: 24 Oct 2006 13:14:35
From: Greg Crinklaw
Subject: Re: Any good memorable comets coming soon? Like Ikeya-Zhang Hale-Bopp
|
canopus56 wrote:
> Greg Crinklaw wrote:
>> The problem is this: it's perfectly alright to say, "comet X was a great
>> comet to me because..." because "great" is entirely subjective. Sure,
>> some people put numbers on it, but that doesn't make their scale any
>> less subjective.
>
> Granted there is a classification problem, e.g. - like the C/1965 S1
> Ikeya-Seki on your site:
>
> http://cometography.com/lcomets/1965s1.html
For the record, that is not my site. That site belongs to Gary Kronk.
Your response is on topic for the thread as a whole; but makes no sense
as a response to what I said, which was about something entirely
different. Please take more care in which messages you respond to in
order to maintain some sort of reasonable flow to the discussion.
Greg
--
Greg Crinklaw
Astronomical Software Developer
Cloudcroft, New Mexico, USA (33N, 106W, 2700m)
SkyTools: http://www.skyhound.com/cs.html
Observing: http://www.skyhound.com/sh/skyhound.html
Comets: http://www.skyhound.com/sh/comets.html
To reply take out your eye
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