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Tonk
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Loc: Leeds, UK, 54N
Re: Comet ISON - Cooked well done? new [Re: boandpokey]
      #6217342 - 11/26/13 02:34 PM

Quote:

http://sohowww.nascom.nasa.gov/data/realtime/c3/1024/latest.html

is that ISON, the faint fuzzy dot in the lower left??






No you have wrong spacecraft and wrong camera - you have the SOHO LASCO C3 camera - see my link above - its the STEREO-B COR2 camera


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boandpokey
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Re: Comet ISON - Cooked well done? new [Re: Tonk]
      #6217344 - 11/26/13 02:36 PM

well it should be visible in that one also???

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Tonk
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Re: Comet ISON - Cooked well done? new [Re: boandpokey]
      #6217348 - 11/26/13 02:38 PM

No the FOV and position (direction to the sun) are entirely different between the two craft and their cameras

It will appear in SOHO C3 but not just yet

Here are some nice graphics showing when, where in each available SOHO, STEREO-A, STEREO-B camera

http://stereo-ssc.nascom.nasa.gov/comet_ison/


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Tom Laskowski
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Re: Comet ISON - Cooked well done? new [Re: boandpokey]
      #6217361 - 11/26/13 02:45 PM

Quote:

http://sohowww.nascom.nasa.gov/data/realtime/c3/1024/latest.html

is that ISON, the faint fuzzy dot in the lower left??




I could be wrong, but the fuzzy thing in the image is M4 and the bright star to the left is Antares.


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bartlebobton
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Reged: 11/26/13

Re: Comet ISON - Cooked well done? new [Re: GlennLeDrew]
      #6217418 - 11/26/13 03:19 PM

Hi Glenn... thanks for taking the time to explain to me a little bit more friction, that's really informative...much appreciated... BB

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Special Ed
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Re: Comet ISON - Cooked well done? new [Re: Tonk]
      #6217488 - 11/26/13 03:49 PM

Quote:

...Here are some nice graphics showing when, where in each available SOHO, STEREO-A, STEREO-B camera

http://stereo-ssc.nascom.nasa.gov/comet_ison/




Tony, thanks for this link.

Whether ISON disintegrates or not we will have an amazing view thanks to all those spacecraft out there.


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Philipp
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Reged: 08/13/06

Re: Comet ISON - Cooked well done? new [Re: Special Ed]
      #6217646 - 11/26/13 05:09 PM

Here is an animation made from SECCHI images from Nov. 22nd to 26th (right until now): https://www.youtube.com/watch?v=G_g6QXObU9w

I am still hoping for a nice surprise in the morning sky after perihelion!

Philipp


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Tonk
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Re: Comet ISON - Cooked well done? new [Re: Philipp]
      #6217861 - 11/26/13 06:55 PM

Quote:

It will appear in SOHO C3 but not just yet




Its now four minutes from 27th November (UK) which is the day ISON enters the SOHO LASCO C3 field of view


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Mirzam
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Re: Comet ISON - Cooked well done? new [Re: Philipp]
      #6217873 - 11/26/13 06:59 PM

What puzzles me is why a reduction in a particular molecular emission would necessarily signify a breakup? It seems more logical to surmise that a reduction would mean removal of an outer compositional layer of material, or if the comet is homogeneous, then everything is suddenly "poof" gone. If the latter was true, then would not the reduction in emissions be a linear function of the remaining volume of the comet? If so, one could model the volume and see if the observations match a reasonable set of model assumptions. A simple break up should increase the emissions of a homogeneous body (due to increased surface area). Depending on the size of the fragments the emissions increase should persist if the fragments are large and decrease to zero if the comet is truly cooked and evaporated. It still looks pretty solid in the images.

JimC


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Tonk
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Re: Comet ISON - Cooked well done? new [Re: Mirzam]
      #6217900 - 11/26/13 07:13 PM

Quote:

It still looks pretty solid in the images.




Visual images do not enable you to see anything of the solid nucleus. You are actually looking at a vast shroud of reflecting dust expelled from the comet. This is why observing at microwave frequecies lets you observe material that has left the surface within the last hour. Its actually days before that material would emerge through the dust shroud, so microwaves are good to see deeper and closer to the necleus.


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Mirzam
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Re: Comet ISON - Cooked well done? new [Re: Tonk]
      #6217910 - 11/26/13 07:19 PM

True. But they are not observing the nucleus as a solid object (as might be done by using linked radar antennae). They are looking at an emission line.

JimC

Edited by Mirzam (11/26/13 07:21 PM)


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Glen A W
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Re: Comet ISON - Cooked well done? new [Re: Mirzam]
      #6217924 - 11/26/13 07:25 PM

It's a matter of scale. The coma might be tens of thousands of miles across, depending upon the comet... The nucleus is probably only a couple of miles diameter for this comet.

The reduction in molecular emission was not for certain to begin with, and there are other interpretations. The best bet is to stay tuned. There is still plenty of chance for a great comet. No one knows what is happening exactly or what will happen.


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brianb11213
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Re: Comet ISON - Cooked well done? new [Re: dyslexic nam]
      #6217928 - 11/26/13 07:29 PM

Quote:

And for the record, I haven't yet read a post on ISON's possible/probable demise that expresses surprise. More like disappointment.



Maybe. Surprise simply isn't logical: the indications for the last few months have been that there was next to no chance that the thing would survive perihelion.

Quote:

People are simply hoping that ISON pulls through and puts on an amazing show.



That really would be a surprise.

It's not a question of whether you see the glass as being half empty or half full, it's a question of what's in the glass. A tenth full of water would be better than completely full of vaccuum.


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Mirzam
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Re: Comet ISON - Cooked well done? new [Re: Glen A W]
      #6217929 - 11/26/13 07:29 PM

Bruce Gary's site has a new photo indicating that the nucleus is still very compact--i.e., any fragments must be very close together.

Gary latest obs

JimC


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brianb11213
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Re: Comet ISON - Cooked well done? new [Re: Mirzam]
      #6217946 - 11/26/13 07:42 PM

Quote:

Depending on the size of the fragments the emissions increase should persist if the fragments are large and decrease to zero if the comet is truly cooked and evaporated. It still looks pretty solid in the images.



"Consistent, rapid fading of the molecular emission lines between Nov 21 & Nov 25 by a factor of at least 20"
Seems pretty clear that outgassing has declined to a relatively small fraction at a time when it should be increasing rapidly due to solar heating. It's the gas that drives off the dust that forms the visible tail & coma, one would expect these to persist for a few days even if the nucleus has completely gone.

There doesn't seem to be any reason why a "virgin" comet should suddenly develop a protective crust so exhaustion of the volatiles is pretty much the only explanation that makes sense.

If we go back a week or so, the sudden increase in dust generation that occurred can easily be explained by disintegration of the nucleus exposing more area to solar heating.

Looked at that way, it all makes sense.

Patience, my friends. Sooner or later a "great" comet will come along. Actually C/2006 P1 McNaught was pretty spectacular as viewed from the southern hemisphere in January 2007 ...


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aa6ww
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Re: Comet ISON - Cooked well done? new [Re: brianb11213]
      #6218052 - 11/26/13 08:34 PM

I'm sure ISON will be fine. These so called "Experts" are making their best guess now, and if they are right, they will get a pat on the back and if they are wrong, then its no big deal because no one has ever taken a core sample of what ISON is really made up of, so no one really knows.
Its probably has a much harder surface area then they "assume" it has, and I really don't see it as being a sun diving comet which will die during its path around the sun.
We just have more information now than we ever have, and think we have to always make predictions.
This is no different than every time there's a large solar flair up, its the end of the world. This is only because we have more data now and can see all of this as it happens, where as before we never could. Its the same thing.
No one really knows, but based on what Ive seen and know of all of this, ISON will be just fine. This is just media hype to gather attention, as is usually the case when things are unpredictable since there is no accountability in what we predict or assume.
As with most things related to astronomy, the more we know, the less we know.
All this "hype" is feeding the less informed, that's all.
I'm looking for a great exit away from the sun and a very nice end of the year show from ISON.
Everyone has to be Miley Cyrus and Kim Kardashian, Just let this play out and enjoy the ISON show at the end of the year.

...Ralph


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BrooksObs
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Re: Comet ISON - Cooked well done? new [Re: aa6ww]
      #6218156 - 11/26/13 09:27 PM

Well, ISON appears on the Nov. 27 01h 41m frame of the SOHO LASCO C3 camera image. I make it to be pretty close to magnitude +2.5 . Admittedly that's a bit disappointing at this heliocentric distance, but far from hopeless. In fact, it seems to perhaps have simply returned to its instrinsic brightness from the weeks prior to experiencing its recent outbursts. Stay tuned, folks!

UPDATE: LASCO image obtained at 02h 44m shows ISON quite similar in physical appearance and brightness to Comet Lovejoy (2011 W3) in LASCO image taken at around perihelion -1.0 day. ISON at this current time is -1.65 days from T. Interesting.

BrooksObs

Edited by BrooksObs (11/27/13 12:09 AM)


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MessiToM
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Reged: 12/21/09

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Re: Comet ISON - Cooked well done? new [Re: BrooksObs]
      #6218343 - 11/26/13 11:04 PM

and a CME? ^
http://sohowww.nascom.nasa.gov/data/realtime/c3/512/


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Ptarmigan
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Re: Comet ISON - Cooked well done? new [Re: Glen A W]
      #6218365 - 11/26/13 11:22 PM

Too early to tell. Should know after Thanksgiving.

Edited by Ptarmigan (11/26/13 11:22 PM)


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mattyfatz
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Re: Comet ISON - Cooked well done? [Re: Ptarmigan]
      #6218442 - 11/27/13 12:04 AM

http://soho.nascom.nasa.gov/hotshots/2013_11_28/

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