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Vronscki
newbie


Reged: 11/27/13

Re: Comet ISON - Cooked well done? new [Re: square_peg]
      #6222564 - 11/28/13 11:46 PM

I have a newbie question about AIA 171 and 193.
Are they different satellites on different positions or are they just different equipment on the same satellite?
tks


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qianniu
sage


Reged: 05/05/07

Loc: Columbus, OH
Re: Comet ISON - Cooked well done? new [Re: square_peg]
      #6222569 - 11/28/13 11:50 PM

This new, brightening object in C3 images, appears to be moving away from the projected path... Yes, want to know what's going on up there!

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MessiToM
scholastic sledgehammer
*****

Reged: 12/21/09

Loc: Huntingdon PA
Re: Comet ISON - Cooked well done? new [Re: qianniu]
      #6222591 - 11/29/13 12:11 AM



it would seem stereo is all we have rite now

Edited by MessiToM (11/29/13 12:12 AM)


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qianniu
sage


Reged: 05/05/07

Loc: Columbus, OH
Re: Comet ISON - Cooked well done? new [Re: MessiToM]
      #6222598 - 11/29/13 12:15 AM

Seems it is developing a tail pointing away from the Sun. Sounds like a comet to me.

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canukLX90
professor emeritus


Reged: 12/25/08

Loc: B.C. Canada
Re: Comet ISON - Cooked well done? new [Re: Tonk]
      #6222607 - 11/29/13 12:21 AM

Looking forward to chasing the bits as what is left of the
comet heads out back into the solar system. Meanwhile there
is still C/2013 R1 Lovejoy....

PJ


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BrooksObs
professor emeritus


Reged: 12/08/12

Re: Comet ISON - Cooked well done? new [Re: qianniu]
      #6222631 - 11/29/13 12:38 AM

I had withdrawn from the world of instant computer communication shortly after 2pm this afternoon to celebrate Thanksgiving with the gathering of all my family members, not returning until only a short time ago. I was amused to see the countless messages from befuddled hobbyists about the goings-on involving ISON's perihelion passage, disappearance, and apparent resurrection.

Just ahead of this post I had responded to an e-mail from a longtime colleague who works with a well known science interest news site regarding embarrassment over declaring ISON dead, in step with NASA's such claim. I responded with the following message:


"Well, hee hee (!), did I not just mention in this afternoon's message to you that ISON might just be pulling a Seki-Lines act as it disappeared?

Perhaps we have a new and previously totally unrecognized sort of behavior that can be exhibited by only sungrazing/sunskirting comets. It certainly would explain some of the odd, yet apparently major, Kreutz objects that were only seen at, or shortly after perihelion passage. Recall that I also commented about the seeming brilliant "stellar" appearance briefly exhibited by Lovejoy as perhaps accounting for other possible Kreutz sightings of the past. Now it remains to be seen just how ISON presents itself to us in the morning sky next week. Will it be a true comet, just a huge tail, or something else altogether?

To quote Gene Barry's grinning scientist character in the 1953 "War of the World's" on first seeing the Martian machines rise up, "This is AMAZING!"

For the benefit of those unfamiliar with comet history, 1962's Comet Seki-Lines looked to a fine big dynamically "new" sunskirting comet. It brightened nicely as it drew steadily nearer to the twilight regions. The comet had attained about -1 in the last days leading up to "T" and was anticipated to be visible in the daytime as an object of -7 at perihelion! Well, that day came and went. All available techniques of the day failed to detect anything and Seki-Line was thought to have met its end. But a few days later yet an intrepid British comet observer nevertheless still dared to look for the vanished Seki-Lines in the very bright evening twilight. What he saw was a brilliant object, fully as bright as Jupiter, looming low over the western horizon! In the following days a beautiful fully developed comet with a tail that grew to 15 to 20-degrees in length met the gaze of all those looking westward during the interval of fading evening twilight.


Does this story sound just a bit familiar?

BrooksObs

Edited by BrooksObs (11/29/13 12:43 AM)


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MessiToM
scholastic sledgehammer
*****

Reged: 12/21/09

Loc: Huntingdon PA
Re: Comet ISON - Cooked well done? new [Re: BrooksObs]
      #6222695 - 11/29/13 01:36 AM

Very Nice ^

Finaly a C3 update. BUT if you click on the full size version it defaults back to the 0018 image
http://sohowww.nascom.nasa.gov/data/realtime/c3/512/

edit, here we go
http://198.118.248.97/data/realtime/c3/1024/latest.html

Edited by MessiToM (11/29/13 01:45 AM)


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Starhunter249
sage


Reged: 06/07/10

Re: Comet ISON - Cooked well done? new [Re: MessiToM]
      #6222718 - 11/29/13 01:58 AM

Thanks for the update MessiTom. It appears in that image compared to previous C3 images that the fan shaped tail is in the process of moving away from the sun.

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MessiToM
scholastic sledgehammer
*****

Reged: 12/21/09

Loc: Huntingdon PA
Re: Comet ISON - Cooked well done? new [Re: Starhunter249]
      #6222720 - 11/29/13 02:00 AM

STERO B gif. pretty cool watching the tail "turn around"
http://stereo.gsfc.nasa.gov/browse/2013/11/29/behind_20131129_cor2_rdiff_512.mpg

Your welcome Starhunter, Iam having too much fun following this online......I need to get to bed.


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Starhunter249
sage


Reged: 06/07/10

Re: Comet ISON - Cooked well done? new [Re: MessiToM]
      #6222725 - 11/29/13 02:04 AM

Ill be up late for while looking for more updates.

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arellanon
member


Reged: 12/12/06

Loc: Alta y Baja California
Re: Comet ISON - Cooked well done? new [Re: Starhunter249]
      #6222768 - 11/29/13 03:13 AM

Quote:

Ill be up late for while looking for more updates.




I'll be up early to see what has happened. Going birding tomorrow morning so I'll check what has happened.


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David Knisely
Postmaster
*****

Reged: 04/19/04

Loc: southeastern Nebraska
Re: Comet ISON - Cooked well done? new [Re: BrooksObs]
      #6222791 - 11/29/13 03:53 AM

I really like this outlook on what is happening:

Schrodinger's Comet


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Tonk
Postmaster
*****

Reged: 08/19/04

Loc: Leeds, UK, 54N
Re: Comet ISON - Cooked well done? new [Re: David Knisely]
      #6222804 - 11/29/13 04:23 AM Attachment (28 downloads)

Good morning! LASCO C3 07:30 - SOHO (ESA & NASA)

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Tonk
Postmaster
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Reged: 08/19/04

Loc: Leeds, UK, 54N
Re: Comet ISON - Cooked well done? new [Re: Tonk]
      #6222809 - 11/29/13 04:35 AM Attachment (22 downloads)

SOHO (ESA & NASA) C3 08:18

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SteveRosenow
professor emeritus
*****

Reged: 07/10/12

Loc: Shelton, Washington
Re: Comet ISON - Cooked well done? new [Re: Tonk]
      #6222817 - 11/29/13 04:50 AM

And now we're onto C3 09:11



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Dave M
Postmaster
*****

Reged: 08/03/04

Loc: Ohio
Re: Comet ISON - Cooked well done? new [Re: SteveRosenow]
      #6222818 - 11/29/13 04:52 AM

It looks Big! now..

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Tonk
Postmaster
*****

Reged: 08/19/04

Loc: Leeds, UK, 54N
Re: Comet ISON - Cooked well done? new [Re: Dave M]
      #6222828 - 11/29/13 05:08 AM

Quote:

It looks Big! now..




Saddly is still a dwarf compared to the incomming spectacle. Oh well its going to be a "regular" comet - one for the likes of me. I actually like mag 6 comets - easy to photograph!


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Tonk
Postmaster
*****

Reged: 08/19/04

Loc: Leeds, UK, 54N
Re: Comet ISON - Cooked well done? new [Re: Tonk]
      #6222841 - 11/29/13 05:18 AM

Can someone knowledgable comment. Back of envelope doodling suggests that the comet rebrightened as its differential velocity between the comet and the solar wind is rapidly reduced. First the solar wind vector and the orbital vector is now rapidly narrowing (becoming more aligned) and the comets velocity is also reducing

I can interpret this as the comet was loosing its coma and tail faster than it was generating new volatile material (at perihelion the solar wind vector is 90 degrees to orbital vector). Now that the velocity of the comet and wind/orbit vectors are reducing this is allowing the comet to again accumulate a coma and tail especially as the wind/orbit vectors become similar. I assume that when the wind vector exceeds the orbit vector that is when the dust tail stars to draw ahead of the comet

Different story for the ion tail as that is governed by the acceleration of various ionised masses in an electric/magnetic field.

The hard part for me is spotting which right now is dust and which is ions. I'm assuming all of what we are seeing is dust that has been sorted by mass. The lighter stuff is on the "wave front" of the tail

We saw this with Lovejoy (C/2011 W3) ??


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brianb11213
Postmaster
*****

Reged: 02/25/09

Loc: 55.215N 6.554W
Re: Comet ISON - Cooked well done? new [Re: Tonk]
      #6222866 - 11/29/13 06:18 AM

Quote:

Can someone knowledgable comment. Back of envelope doodling suggests that the comet rebrightened as its differential velocity between the comet and the solar wind is rapidly reduced. First the solar wind vector and the orbital vector is now rapidly narrowing (becoming more aligned) and the comets velocity is also reducing

I can interpret this as the comet was loosing its coma and tail faster than it was generating new volatile material (at perihelion the solar wind vector is 90 degrees to orbital vector). Now that the velocity of the comet and wind/orbit vectors are reducing this is allowing the comet to again accumulate a coma and tail especially as the wind/orbit vectors become similar. I assume that when the wind vector exceeds the orbit vector that is when the dust tail stars to draw ahead of the comet

Different story for the ion tail as that is governed by the acceleration of various ionised masses in an electric/magnetic field.

The hard part for me is spotting which right now is dust and which is ions. I'm assuming all of what we are seeing is dust that has been sorted by mass. The lighter stuff is on the "wave front" of the tail

We saw this with Lovejoy (C/2011 W3) ??



Yes I largely agree.

There are a couple of other points which need to be taken into account.

Firstly, the stuff seen by the solar observatories is in wavebands which would not include the major cometary emissions. So what is being seen is dust & only dust. Any "sizeable" individual fragments of the nucleus would be invisibly small. The dust we're seeing now is the debris from the disintegration which I believe occurred several days before perihelion ... If the nucleus survived it should have been brightest at perihelion when there's most light for it to reflect plus a very high rate of dust production. It vanished, therefore ...

Secondly, as I pointed out yesterday, although the "trailing" dust particles had a lower approach speed than the "leading" ones, after perihelion the leaders will slow down faster due to having had more gravitational influence - whereas the trailers, being lighter, will be more influenced by solar radiation pressure - the net effect being to concentrate the remnants.

In any case even the most optimistic people seem to agree that the exiting "comet" is way, way less bright than it was at the same distance on the way in.

Even Monty Python's parrot existed, as a corpse. Ex-comet Ison is now a wraith ...


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SteveRosenow
professor emeritus
*****

Reged: 07/10/12

Loc: Shelton, Washington
Re: Comet ISON - Cooked well done? new [Re: Tonk]
      #6222886 - 11/29/13 06:55 AM

Quote:

Can someone knowledgable comment. Back of envelope doodling suggests that the comet rebrightened as its differential velocity between the comet and the solar wind is rapidly reduced. First the solar wind vector and the orbital vector is now rapidly narrowing (becoming more aligned) and the comets velocity is also reducing

I can interpret this as the comet was loosing its coma and tail faster than it was generating new volatile material (at perihelion the solar wind vector is 90 degrees to orbital vector). Now that the velocity of the comet and wind/orbit vectors are reducing this is allowing the comet to again accumulate a coma and tail especially as the wind/orbit vectors become similar. I assume that when the wind vector exceeds the orbit vector that is when the dust tail stars to draw ahead of the comet

Different story for the ion tail as that is governed by the acceleration of various ionised masses in an electric/magnetic field.

The hard part for me is spotting which right now is dust and which is ions. I'm assuming all of what we are seeing is dust that has been sorted by mass. The lighter stuff is on the "wave front" of the tail

We saw this with Lovejoy (C/2011 W3) ??




Here's my $.02, or however you want to adjust it for inflation...

First, I think the speed in which ISON was travelling as it passed perihelion, was simply too fast to allow the sun to do a lot of damage at least for the near term.

I agree that there may be some significant change - key words being "may be", but judging from my readings into Comet C/2011 W3 Lovejoy and Comet C/1962 C1 Seki-Lines, I suspect we're in for nearly-identical performances.

For one, C/2011 W3 passed only 80,000 km above the surface of the sun. It was also very much smaller than the nucleus of C/2012 S1 ISON, at 1/9th the size. At last estimate, Comet ISON's nucleus was estimated to be at least the size of Manhattan. Lovejoy's nucleus on the other hand, was in the range of anywhere between 500-1000 feet at maximum. The speed in which ISON was traveling through perihelion, leads me to believe that it is really quite possible for a pretty considerable chunk of ISON to remain relatively intact - and even possibly completely intact. I say this because ISON also traveled through perihelion at a much greater distance from the sun itself, much greater than that of Lovejoy.

Second, the speed. While Lovejoy traveled faster (estimated to be around 333 miles per second, or 2% of the speed of light), ISON's speed was only marginally slower - at about 1/6th slower than Lovejoy - and that slower speed is only attributed to the separation distance between the surface of the sun and ISON's nucleus. By comparison and separation distance, it would appear that ISON and Lovejoy - if traveling at the same distance from the sun - would have been traveling at nearly the same speed. Due to that theory, I believe it stands as much a greater chance of survival (at least for now), as did Lovejoy did in 2011.


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