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boandpokey
sage
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Reged: 07/25/13

Loc: Auburndale, Fl
Re: Comet ISON - Cooked well done? new [Re: SteveRosenow]
      #6219400 - 11/27/13 01:45 PM

In other news, there's talk that the lack of a visible gas tail might mean the nucleus has disintegrated or otherwise gone dead

http://science.nasa.gov/media/medialibrary/2011/12/16/lovejoy_c3_anim2.gif


looks very similar to Lovejoy

good news!?

Edited by boandpokey (11/27/13 01:46 PM)


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BrooksObs
professor emeritus


Reged: 12/08/12

Re: Comet ISON - Cooked well done? new [Re: SteveRosenow]
      #6219523 - 11/27/13 02:42 PM

Matthew Knight (Lowell Obs.) posts:

“Comet ISON has brightened dramatically since it entered the SOHO C3 (note that C3 is the name of the telescope, it is not referring to the molecule) field of view yesterday. In the clear filter images it had an apparent V magnitude of 2.5 on Nov 27.05 when it entered the field of view and has increased steadily in brightness to mag 0.5 on Nov 27.54. Note that it began saturating the detector soon after entering the C3 field of view and I am employing a correction that I developed for C/2011 W3 Lovejoy. This brightening behavior is similar to typical brightening by Kreutz comets in the SOHO fields of view.”

My old friend Karl Battams (NRL) now reports:

“Based on the photometry, and the visual appearance of the comet in the SOHO LASCO data, we have updated the Current Status page to tell observers to plan for a negative magnitude object. A conservative estimate would be -1, but -3 or -4 is certainly reasonable at this point."


Personally, I'm sticking with my earlier (published in S&T) estimate of a brief peak at around -6 shortly after perihelion passage tomorrow. As of 16:18UT, I'm rating ISON's current magnitude at 0 , the comet having brightened by roughly 2.5 magnitudes since last evening. Keep your fingers crossed!

BrooksObs

Edited by BrooksObs (11/27/13 02:45 PM)


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Vronscki
newbie


Reged: 11/27/13

Re: Comet ISON - Cooked well done? new [Re: BrooksObs]
      #6219618 - 11/27/13 03:15 PM

Nov 27.54 ?
For me, it's stuck in 27.48 (16:18)


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godra
newbie


Reged: 10/08/10

Loc: Kragujevac,Serbia
Re: Comet ISON - Cooked well done? new [Re: Vronscki]
      #6219838 - 11/27/13 05:03 PM

Ison is now -1.5mag on LASCO C3 20:42 image!!!

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Glen A W
sage


Reged: 07/04/08

Loc: WEST VIRGINIA USA
Re: Comet ISON - Cooked well done? new [Re: godra]
      #6219899 - 11/27/13 05:33 PM

This is very, very good news, but remember, the worst - for the comet - is yet to come.

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MessiToM
scholastic sledgehammer
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Reged: 12/21/09

Loc: Huntingdon PA
Re: Comet ISON - Cooked well done? new [Re: Glen A W]
      #6219900 - 11/27/13 05:34 PM

Yes shes a blooming! Trying not to think about that ^

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Phillip Creed
Idiot Seeking Village
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Reged: 07/25/06

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Re: Comet ISON - Cooked well done? new [Re: BrooksObs]
      #6219938 - 11/27/13 05:49 PM

Quote:

Personally, I'm sticking with my earlier (published in S&T) estimate of a brief peak at around -6 shortly after perihelion passage tomorrow. As of 16:18UT, I'm rating ISON's current magnitude at 0 , the comet having brightened by roughly 2.5 magnitudes since last evening. Keep your fingers crossed!

BrooksObs




John,

If it gets north of -3 or so, would it be visible simply by projecting the sun's (and comet's) image onto a piece of paper since the comet's angular separation from the sun will be *reeeeeeally* small tomorrow?

Clear Skies,
Phil


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BrooksObs
professor emeritus


Reged: 12/08/12

Re: Comet ISON - Cooked well done? new [Re: Phillip Creed]
      #6220038 - 11/27/13 06:35 PM

Sadly, Phil, no. In fact, under no circumstances can a daytime sungrazing comet become sufficiently bright to be seen by projection. T.Seki tried this approach with his Great Comet back in '65, but probably failed...even though the comet was between magnitude -10 and -15 at the time! In the case of ISON, it is even unlikely that the average amateur will be able to detect it even if it does attain -6. Because of ISON's extreme proximity to the solar disk while sufficiently bright for daylight observation, glimpses might only be possible through the employing of very specialized narrow band-pass Sodium-line filters, or other unusual approaches.

BrooksObs


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Mirzam
Post Laureate
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Reged: 04/01/08

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Re: Comet ISON - Cooked well done? new [Re: BrooksObs]
      #6220098 - 11/27/13 07:02 PM

Nearly 4,000x brightening (10 magnitudes) in the past 2 weeks. Not too shabby for a cooked comet!

JimC


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goodricke1
member


Reged: 05/18/13

Loc: Ireland
Re: Comet ISON - Cooked well done? new [Re: Mirzam]
      #6220106 - 11/27/13 07:06 PM

Just imagine if it really had been 50km in diameter as they originally thought, would've been the Comet of the Millennium!

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BrooksObs
professor emeritus


Reged: 12/08/12

Re: Comet ISON - Cooked well done? new [Re: BrooksObs]
      #6220107 - 11/27/13 07:08 PM

In my opinion, the Lasco image of 23:06UT indicates a full-blown sungrazer/sunskirter rapidly approaching perihelion. Nothing about it is indicative of any break-up to my eye in spite of what is being claimed, or even that this comet could be only a minor cometary body, as also has been proposed. The coma is surely at least of magnitude -1.5 at present and brightening very rapidly. It has made up all its lost ground from yesterday when it first entered the Lasco C3 field as compared with my magnitude predictions and may now even exceed my expectations.

The dust tail is very strong, broad and thick, not at all like the spindley tails shown by the majority of smaller sungrazers. It is even much better than that of Lovejoy 2011 W3 pre-T! And look at that odd, spike-like tail coming out of the northern edge of the dust tail!

If all these features and signs continue to develop through until tomorrow morning at the current pace then a truly grand show could await us in the morning sky of late next week. Be prepared!.

BrooksObs

Edited by BrooksObs (11/27/13 10:40 PM)


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Unknownastron
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Reged: 04/06/05

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Re: Comet ISON - Cooked well done? new [Re: BrooksObs]
      #6220133 - 11/27/13 07:28 PM

In 2012 I observed an annular solar eclipse and a solar transit of the planet Venus. Both were predicted with an accuracy in both time and space within a range far smaller that I can measure. We come to expect all astronomical events to be predictable to that degree. Professionals can measure and predict the orbit within a shade of that accuracy but even the celestial mechanics of comets is less perfect than most bodies in space due to jet effects and such. Predictions of magnitude, size and appearance of the coma and tail/tails do not have sufficient scientific data to be accurate. David Levy's adage must be repeated again and again, "Comets are like cats, they have tails and do precisely what they want".
We will have to wait day by day to see what happens. But that sure is fun!
Clear skies and clean glass,
Mike


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BrooksObs
professor emeritus


Reged: 12/08/12

Re: Comet ISON - Cooked well done? new [Re: Unknownastron]
      #6220217 - 11/27/13 08:07 PM

Quote:

David Levy's adage must be repeated again and again, "Comets are like cats, they have tails and do precisely what they want".

Mike




A true statement usually applicable only to those lacking a broad and intimate familiarity with simlar past examples. Honestly, much of the most recent highly specialized data has no earlier observations of a like nature for comparison with to allow them to be meaningful interperted. Too much about ISON has just been no more than pure speculation based on the beliefs of the particular author, or in hast to be heard/published should something they say actually happen to come to pass.

BrooksObs

Edited by BrooksObs (11/27/13 08:33 PM)


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David Knisely
Postmaster
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Reged: 04/19/04

Loc: southeastern Nebraska
Re: Comet ISON - Cooked well done? new [Re: Octans]
      #6220659 - 11/28/13 01:52 AM

Yup, I am looking at the 06:18 UT image and the comet appears to have a tail length of at least around five degrees (the width of the C3 coronagraph image is about 16 degrees). The CCD blooming spikes are really getting prominent now, so the comet is definitely a bright object, although exactly how bright remains to be seen. I just hope that narrow wimpy dust tail component really starts to get going, or this comet (if it survives) might not be putting on too much of a show. Clear skies to you.

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BJS
member


Reged: 05/23/09

Loc: NW Ohio
Re: Comet ISON - Cooked well done? new [Re: David Knisely]
      #6220919 - 11/28/13 08:59 AM

Well the latest c3 update (12:54UT) shows the blooming spikes greatly decreased. I did hear somewhere that the imaging team was going to decrease exposure time so maybe that is the reason? Dust tail does not seem any more prominent either....
Fingers crossed!
Brian


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qianniu
sage


Reged: 05/05/07

Loc: Columbus, OH
Re: Comet ISON - Cooked well done? new [Re: BJS]
      #6220928 - 11/28/13 09:05 AM

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

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Nick Anderson
super member


Reged: 04/21/13

Loc: Virginia, USA
Re: Comet ISON - Cooked well done? new [Re: qianniu]
      #6220949 - 11/28/13 09:15 AM

Quote:

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




Indeed, I was thinking the same thing. The horizontal spike is almost gone...

-Nick Anderson


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BrooksObs
professor emeritus


Reged: 12/08/12

Re: Comet ISON - Cooked well done? new [Re: Nick Anderson]
      #6220977 - 11/28/13 09:34 AM

To my understanding and correct me if I am wrong as I am not normally as solar observer, the Lasco SOHO coronographs are equipped with radial density gradinent filters so as to not overwhelm the cameras from the brightness of coronal features progressively closer to the solar disk. This may account for the seeming decline in the "bloom spikes", although to just what degree I don't know. Certainly, if one stands aways from the computer monitor and views the entire SOHO field, it is obvious that fainter stars progressives fade with their approach to the occulting disk. Most unfortunately, the LASCO site is so overloaded by folks trying to get on currently that old image sequences showing things like the brighter planets passing behind the Sun at superior conjunction cannot be accessed for directly viewing the degree to which they fade. It is also possible that the exposure time for each frame is being shortened to reduce overexposure of the comet's image.

Right now (14:23UT), judging by the main tail's brightness development and continued lengthening - apparently the ion tail, not the slightly curving adjacent one which then would be dust, but oddly short - implies continuing healthy outgassing by the nucleus.

Stay tuned!

BrooksObs

Edited by BrooksObs (11/28/13 09:36 AM)


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Nick Anderson
super member


Reged: 04/21/13

Loc: Virginia, USA
Re: Comet ISON - Cooked well done? new [Re: BrooksObs]
      #6220995 - 11/28/13 09:46 AM

Quote:

To my understanding and correct me if I am wrong as I am not normally as solar observer, the Lasco SOHO coronographs are equipped with radial density gradinent filters so as to not overwhelm the cameras from the brightness of coronal features progressively closer to the solar disk. This may account for the seeming decline in the "bloom spikes", although to just what degree I don't know. Certainly, if one stands aways from the computer monitor and views the entire SOHO field, it is obvious that fainter stars progressives fade with their approach to the occulting disk. Most unfortunately, the LASCO site is so overloaded by folks trying to get on currently that old image sequences showing things like the brighter planets passing behind the Sun at superior conjunction cannot be accessed for directly viewing the degree to which they fade. It is also possible that the exposure time for each frame is being shortened to reduce overexposure of the comet's image.

Right now (14:23UT), judging by the main tail's brightness development and continued lengthening - apparently the ion tail, not the slightly curving adjacent one which then would be dust, but oddly short - implies continuing healthy outgassing by the nucleus.

Stay tuned!

BrooksObs




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


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Nick Anderson
super member


Reged: 04/21/13

Loc: Virginia, USA
Re: Comet ISON - Cooked well done? [Re: Nick Anderson]
      #6221011 - 11/28/13 09:55 AM

Can anyone explain the great time leap I'm seeing from 09:18 and 12:54?

-Nick Anderson


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