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timtrice
sage


Reged: 08/01/13

Loc: Katy, TX
Re: Comet ISON - Cooked well done? new [Re: Nick Anderson]
      #6221019 - 11/28/13 10:03 AM

satellite was out of contact: https://twitter.com/SungrazerComets/status/406042085859414017

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Nick Anderson
super member


Reged: 04/21/13

Loc: Virginia, USA
Re: Comet ISON - Cooked well done? new [Re: timtrice]
      #6221031 - 11/28/13 10:09 AM

Ok, thanks for the info.

-Nick Anderson


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boandpokey
sage
*****

Reged: 07/25/13

Loc: Auburndale, Fl
Re: Comet ISON - Cooked well done? new [Re: qianniu]
      #6221053 - 11/28/13 10:18 AM

Quote:

The LASCO C2 image at 12:48 is not looking good. I did not see a coma.




indeed, looks bad


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BJS
member


Reged: 05/23/09

Loc: NW Ohio
Re: Comet ISON - Cooked well done? new [Re: boandpokey]
      #6221076 - 11/28/13 10:30 AM

The 14:36 c2 image shows the coma. I do not see any ccd spike but i am unsure if that is normal for this camera or not? EIther way, it does not look as bright as Lovejoy was just before passage. Fun to watch and see what happens today!

Brian


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Dave M
Postmaster
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Reged: 08/03/04

Loc: Ohio
Re: Comet ISON - Cooked well done? new [Re: BJS]
      #6221084 - 11/28/13 10:32 AM

Looking at the Lasco C2 Loop it appears ok ?

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BrooksObs
professor emeritus


Reged: 12/08/12

Re: Comet ISON - Cooked well done? new [Re: Nick Anderson]
      #6221116 - 11/28/13 10:46 AM

Quote:


Looking at this animation of the passage of C/2011 W3 (Lovejoy) as seen by SOHO, it does seem that the spike diminishes shortly before being occulted by the disk...
http://science.nasa.gov/media/medialibrary/2011/12/16/lovejoy_c3_anim2.gif

-Nick Anderson




Also note the rapid fading out of the star background approaching the Sun. Further, watch Lovejoy's bloom spikes get much larger as the comet retreats from the Sun post-T, right at the time that there is a frame jump to a slightly later time.

BrooksObs


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Special Ed
Postmaster
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Reged: 05/18/03

Loc: Greenbrier Co., WV 38N, 80W
Re: Comet ISON - Cooked well done? new [Re: BrooksObs]
      #6221150 - 11/28/13 11:03 AM

They are going to re-point the SDO spacecraft to take pics and video of ISON at perihelion with images posted by 1300 UT.
http://cometison.gsfc.nasa.gov/


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timtrice
sage


Reged: 08/01/13

Loc: Katy, TX
Re: Comet ISON - Cooked well done? new [Re: boandpokey]
      #6221173 - 11/28/13 11:15 AM

Someone just posted this on reddit

https://pbs.twimg.com/media/BaK2uJXCUAApwDP.jpg:large

EDIT: According to the individual who tweeted the pic it was from LASCO C2.

Edited by timtrice (11/28/13 11:30 AM)


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Tonk
Postmaster
*****

Reged: 08/19/04

Loc: Leeds, UK, 54N
Re: Comet ISON - Cooked well done? new [Re: timtrice]
      #6221194 - 11/28/13 11:24 AM

Nice SOHO image here

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herrointment
Post Laureate
*****

Reged: 03/12/11

Loc: North of Hwy. 64
Re: Comet ISON - Cooked well done? new [Re: Tonk]
      #6221251 - 11/28/13 11:47 AM

Wow!

Thanks for all the links and info, everyone....very interesting!


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arellanon
member


Reged: 12/12/06

Loc: Alta y Baja California
Re: Comet ISON - Cooked well done? new [Re: herrointment]
      #6221296 - 11/28/13 12:05 PM

Quote:

Wow!

Thanks for all the links and info, everyone....very interesting!




Yeah, what a cool Thanksgiving! Turkey, football, and ISON!



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Relativist
Post Laureate
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Reged: 10/11/03

Loc: OC, CA, USA
Re: Comet ISON - Cooked well done? new [Re: herrointment]
      #6221302 - 11/28/13 12:07 PM

My opinion, this is like a fly passing the back of an elephant, there is a chance the tail will reach out and swat it. If there is a CME in the comets path then it will probably be gone. A CME in effect puts up a fountain of material, and at the speeds the comment is going that's a lot of force. ( friction here will be proportional to the density and also some power of the velocity - it goes up as velocity goes up)

In addition to the various factors Glenn correctly pointed out the spin, and orientation of the spin, of the comet combined with tidal forces will have a say on what happens.

Combine the irregular surface with the spin, any friction force will also have the effect of unevenly putting pressure on the comet.

I guess the main point I'm trying to make is, this close to the Sun, without knowing way more about the comet, we cannot dismiss the possibility of the Sun joining us for a thanksgiving meal.

I for one hope she enjoys the tasty treat.


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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: Relativist]
      #6221336 - 11/28/13 12:29 PM

Quote:

A CME in effect puts up a fountain of material, and at the speeds the comment is going that's a lot of force. ( friction here will be proportional to the density and also some power of the velocity - it goes up as velocity goes up)




However most of the forces on a comet ion tail from a CME are not from particles but from the magnetic and electric fields sweeping past. These interact directly with the ionised atoms/molecules in the ion tail. The particle density even in a CME is supprisingly low - a good vacuum in fact!

The reference event was 3 years ago when images showed the ion tail of Comet Enke being ripped off by the magnetic/electric fields of a passing CME


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SteveRosenow
professor emeritus
*****

Reged: 07/10/12

Loc: Shelton, Washington
Re: Comet ISON - Cooked well done? new [Re: Tonk]
      #6221350 - 11/28/13 12:36 PM

The SODO/AIA cameras are starting to come online now.

http://cometison.gsfc.nasa.gov/


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Special Ed
Postmaster
*****

Reged: 05/18/03

Loc: Greenbrier Co., WV 38N, 80W
Re: Comet ISON - Cooked well done? new [Re: Tonk]
      #6221355 - 11/28/13 12:38 PM

More info and pics at the S&T ISON blog. They are reporting a big drop in brightness and not attributing it to the camera techs decreasing the exposure.

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Jure Atanackov
super member


Reged: 05/04/10

Re: Comet ISON - Cooked well done? new [Re: Special Ed]
      #6221372 - 11/28/13 12:44 PM

Negative daytime observations Nov 28.48-28.56 UT

I report negative daytime observation of comet C/2012 S1 (ISON) in the interval Nov 27.48-28.56UT from Krvavec mountain, Slovenia (4617'N, 1432'E). 11x70B, 20x110B and 20-cm f/6 Newtonian (at 48x) were used. The location is at 1450 m elevation, observing conditions were perfect - cold, dry airmass with virtually no aerosols; hiding the Sun behind a distant roof the sky transitioned to deep blue immediately.

2013 Nov 28.48UT: m1=[-3.0: ...11x70B, Jure Atanackov (Krvavec, Slovenia)
2013 Nov 28.56UT: m1=[-2.0: ...20-cm L (48x), Jure Atanackov (Krvavec, Slovenia)

Observations started with (mounted) 11x70B at Nov 28.48UT. The Sun was placed behind a distant (20-30 m) roof edge. The position of the comet was scanned by three observers (also Janez Kos, Klemen Čotar) for the next hour with negative results. 20x110B were then used at Nov 28.52UT with the same technique, but also failed to show the comet. At Nov 28.53UT we switched to the 20-cm f/6 Newtonian at 48x. A Wratten #21 filter and an Astrodon I-series luminance filter were also occasionally used to enhance contrast, but to no effect. At Nov 28.54UT, using no filter, I could easily see Antares at 5.5 SE of the Sun, but could not detect the comet. A very thin layer of high cloud then began intermittently interfering with observations until Nov 28.56UT when the Sun&comet had sunk low in the southwest and sky background brightness had increased significantly. The limiting magnitude for the comet was estimated based on the visibility of Antares and previous experience in observing planets close to the Sun.


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kevin M13
sage


Reged: 03/07/09

Loc: Upstate NY
Re: Comet ISON - Cooked well done? new [Re: Jure Atanackov]
      #6221410 - 11/28/13 12:58 PM

Seems as thought the SOHO site has crashed.

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BJS
member


Reged: 05/23/09

Loc: NW Ohio
Re: Comet ISON - Cooked well done? new [Re: kevin M13]
      #6221418 - 11/28/13 01:01 PM

Try this link for SOHO site.

http://198.118.248.97/data/realtime/c3/512/

Brian


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MessiToM
scholastic sledgehammer
*****

Reged: 12/21/09

Loc: Huntingdon PA
Re: Comet ISON - Cooked well done? new [Re: BJS]
      #6221423 - 11/28/13 01:04 PM

live coverage
http://www.youtube.com/watch?v=q03I1B_yrPg&feature=youtu.be


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Special Ed
Postmaster
*****

Reged: 05/18/03

Loc: Greenbrier Co., WV 38N, 80W
Re: Comet ISON - Cooked well done? [Re: Jure Atanackov]
      #6221436 - 11/28/13 01:08 PM

Jure,

Thanks for the report. If you guys couldn't see it through all that hardware, then I never had a chance with the unaided eye.


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