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C/2012 S1 ISON

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#51 MDavid

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Posted 29 April 2013 - 10:19 AM

...We know how disappointing that one turned out to be after all the hype that surrounded it.

PanSTARRS and ISON appear to share a high degree of dust production while still quite some distance from the Sun. However, ISON seems to be intrinsically only about 1/5 the brightness of PanSTARRS. The combination is not particularly indicative of a comet with great prospects, I'm afraid.

BrooksObs


Personally, my family and I really enjoyed PanSTARRS as we had a great time seeing it adjacent to the waxing 1% illuminated crescent moon (using 9x63 binos). It was magnificent and it was my kids first comet. I suppose it helps going in to never believe the hype and have a little history to fall back on...I'll echo Fred L. Whipple, "If you must bet, bet on a horse, not a comet!"

Clear Skies!

#52 John Wunderlin

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Posted 29 April 2013 - 10:32 AM

The most recent visual sighting seems to have been reported about two weeks ago, at +15.5 , while perhaps more reliable imaging techniques indicate closer to +17


I've been using a CCD with CCDOps software to calculate the magnitudes in this thread which seem to be fairly close to what others have reported. It appears the comet has dimmed once more, but it is clearly still brighter than Mag 16 in my data- in my data from last night it was right next to a mag 15.9 star and is clearly brighter than that. I'm hoping to have my latest results processed in a couple of days.

ISON seems to be even less predictable than past comets, but it's going to be very close to the Sun- should be a good show even if it doesn't live up to the ridiculous hype... Visible during the day? Sure it will lol.

#53 REC

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Posted 29 April 2013 - 11:57 AM

I went to a lecture at the NEAF show about ISON. It was by Bob Berman from S&T and although he was optimistic about it in his talk, there seemed to be just a small lack of enthusiasm I detected about how great it would really be. He is taking a tour group to see it in the morning skies from Chili and it sounded like it will be brighter then it will be after sunset in the north.

So we shall see later this year about it's prospects. I would sure like it to be like Hale-Bopp or brighter:)

Bob

#54 hiro

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Posted 30 April 2013 - 06:26 AM

I imaged the comet through the short dark window on April 28, 2013.
The comet looks to be around magnitude 15.5 compared to the surrounding stars.

Posted Image

The original is in my flickr page as usual.
http://www.flickr.co...roc/8695598456/

Thank you for looking.

#55 Rich (RLTYS)

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Posted 02 May 2013 - 05:46 AM

I also just recently imaged Ison and its still not really brightening. I'm really starting to wonder... :question:

Rich (RLTYS)

#56 Tonk

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Posted 02 May 2013 - 02:42 PM

Take a look at the predicted light curves and the measured brightness (bottom of page here - http://www.aerith.ne...2S1/2012S1.html )

Starting to tell a story :( It all started to go wrong back in January

#57 Rich (RLTYS)

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Posted 03 May 2013 - 05:06 AM

Dosen't look too good. :(

Rich (RLTYS)

#58 hfjacinto

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Posted 12 May 2013 - 10:05 PM

Saw it visually on Friday, that was through a 25" goto reflector, not impressed, very small, looked like a planetary nebula no tail was visible. It was there, but seriously not impressive at all. If it wasn't for goto and the Sky would never have guess it was a comet.

#59 BrooksObs

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Posted 14 May 2013 - 07:45 AM

In my opinion the situation with ISON is trending toward the likelihood of its becoming another Comet Lovejoy: an object which with decreasing heliocentric distance will show only relatively limited activity and remain fairly obscure prior to reaching perihelion. As it rounds the Sun ISON's nucleus will either undergo a disruption event, or experience a dramatic dust-release. Either instance will result in the generation of an enormous, but only briefly fairly bright tail, the entire object fading out much sooner than most will be anticipating. Prime observability will be limited to just a week, or two, in early December before the "big" comet may seem to evaporate almost overnight into nothingness.

This scenario has played out in sun-skirting/sungrazing comets a surprising number of times over the last two centuries. Probably one of the best recent examples (beyond C/Lovejoy) being C/Wilson-Hubbard in 1961.

BrooksObs

#60 krp

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Posted 14 June 2013 - 05:50 PM

Here's a new article about ISON: Sky and Telescope If it's anything like the pictures I've seen of Lovejoy than I'm really looking forward to it.

#61 BrooksObs

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Posted 15 June 2013 - 08:56 AM

Here's a new article about ISON: Sky and Telescope If it's anything like the pictures I've seen of Lovejoy than I'm really looking forward to it.


Just appreciate that the images of C/Lovejoy we all ooohed and aaahed over were the result of extended exposures and don't necessarily reflect what a visual observer could see at the same time. In fact, when Lovejoy's tail was reaching around 35 and 45-degrees on forced images virtually nothing at all had been visible to the naked eye for quite some time.

BrooksObs

#62 krp

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Posted 19 June 2013 - 02:10 PM

Here's a new article about ISON: Sky and Telescope If it's anything like the pictures I've seen of Lovejoy than I'm really looking forward to it.


Just appreciate that the images of C/Lovejoy we all ooohed and aaahed over were the result of extended exposures and don't necessarily reflect what a visual observer could see at the same time. In fact, when Lovejoy's tail was reaching around 35 and 45-degrees on forced images virtually nothing at all had been visible to the naked eye for quite some time.

BrooksObs

I realize that, I'm hoping to get some long exposure shots of the comet myself.
It just occurred to me that the best time to view the comet (December 10-14) coincides with the Geminid meteor shower on the 13 and 14th. Both of them should be visible in the pre-dawn sky. The waxing gibbous moon will be up most of the night but after it sets there will be 1-2 hours of darkness. That's something I don't want to miss, I might have to head south if the comet lives up to expectations.

#63 _Z_

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Posted 16 July 2013 - 02:05 PM

NASA just released a timeline on Comet ISON that includes which missions will be observing the comet along with a couple of key dates for it.

So far:
Deep Impact SWIFT
Spitzer
Swift
Hubble

Up next:
BRRISON
Curiosity
Opportunity
Hubble again
MESSENGER
FORTIS
Stereo-A
Stereo-B
SOHO
SDO

http://www.nasa.gov/...gerous-journey/

#64 Tonk

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Posted 17 July 2013 - 09:05 AM

Well its bound to fizzle out now that lot is looking - would put anyone off :lol:

#65 John_G

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Posted 17 July 2013 - 05:41 PM

PDF for ISON Jan/14 attached. 15x70s.

Attached Files



#66 BSJ

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Posted 30 July 2013 - 07:53 AM

http://www.dailymail...century-fizz...

#67 BrooksObs

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Posted 30 July 2013 - 11:15 AM

It would be so much better for all concerned if only the "media" would limit itself to just reporting on political slop and TV's "reality" shows. The media - with the assistance of a few "spokesman scientists" - have managed to spin the ISON prognostications to so many extremes since the comet's discovery that anyone in the general public must by now regard all astronomers as idiots and I would not blame them.

As far as I am concerned, the topsy-turvy ISON story has grown to become worse than the Kohoutek flap of 1973 ever was. And now we are seeing conclusions being drawn and presented as new infomation when, in fact, there has been absolutely no new data taken on the comet's development in 4-6 weeks! This is science? I'm almost ashamed.

BrooksObs

#68 Tonk

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Posted 02 August 2013 - 11:24 AM

Calm down John ;) This is the UK's Daily Mail which is well known for publishing hyperbole and fiction and dressing it up as fact. Brits are largely not fooled by such antics (other than the Daily Mail's loyal following - a certain gullible type!). I'd be far more concerned if such wild claims of large tailed super bright comets turned up in the Independent.

However most of the info in the article appears reasonable - its just the headline that grates as it clearly just a attention grabber by quoting the hyperbole aspect

#69 Octans

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Posted 03 August 2013 - 12:17 AM

However most of the info in the article appears reasonable - its just the headline that grates as it clearly just a attention grabber by quoting the hyperbole aspect


That reminds me of one of the worst offenders -- weather.com. One time, it featured an article on the comet just like any other of the hundreds you see out there...except on their front page, they linked it with a title something like "Comet Headed STRAIGHT For Earth" with a picture of some massive asteroid impacting the planet. :foreheadslap: The article itself was reasonable (although I don't think they wrote it).

#70 Alvan Clark

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Posted 03 August 2013 - 11:31 AM

Wouldn't sungrazers be the hardest to predict? It seems the comet could be anything from the comet of the century to completely vaporize and never be seen again.

I remember many years ago Bortle was quoted in the Boston Globe as saying that Comet Hyakutake would be the one to see (over Hale-Bopp). I think he got that one right.

#71 brianb11213

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Posted 03 August 2013 - 12:02 PM

Wouldn't sungrazers be the hardest to predict? It seems the comet could be anything from the comet of the century to completely vaporize and never be seen again.

They're actually rather easy to predict: just predict that they'll fizzle and you'll almost always be right.

The hard ones to predict seem to be the short period comets with multiple returns which have relatively large perihelion distances. Halley (1/P) was about 2 mags fainter than predicted at its 1986 return; OTOH Holmes (17/P) overperformed by at least 10 mags at its 2007 return. And don't forget Schwassmann-Wachmann (29/P) which has a near circulr orbit with a perihelion outside Jupiter's orbit yet is pretty unpredictable, with flare-ups of several magnitudes at irregular intervals.

I remember many years ago Bortle was quoted in the Boston Globe as saying that Comet Hyakutake would be the one to see (over Hale-Bopp). I think he got that one right.

Yes, Hyakutake was a spectacular sight - but only if you had a good dark sky in the few days when it was close to Earth.

#72 BrooksObs

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Posted 03 August 2013 - 12:23 PM

Wouldn't sungrazers be the hardest to predict? It seems the comet could be anything from the comet of the century to completely vaporize and never be seen again.

They're actually rather easy to predict: just predict that they'll fizzle and you'll almost always be right.

The hard ones to predict seem to be the short period comets with multiple returns which have relatively large perihelion distances. Halley (1/P) was about 2 mags fainter than predicted at its 1986 return; OTOH Holmes (17/P) overperformed by at least 10 mags at its 2007 return. And don't forget Schwassmann-Wachmann (29/P) which has a near circulr orbit with a perihelion outside Jupiter's orbit yet is pretty unpredictable, with flare-ups of several magnitudes at irregular intervals.

I remember many years ago Bortle was quoted in the Boston Globe as saying that Comet Hyakutake would be the one to see (over Hale-Bopp). I think he got that one right.

Yes, Hyakutake was a spectacular sight - but only if you had a good dark sky in the few days when it was close to Earth.


Whoa there!

When intrinsically brighter than magnitude +7.0 true Kreutz sungrazing comets carry a virtual guarantee of being spectacular. They are perhaps the easiest of all to predict. Only the related tiny cometary shards seen by the SOHO, et al., satellites behave erratically.

On the other hand, other small perihelion distance comets (they are not rightly to be considered as sungrazers), like ISON, PanSTARRS, and McNaught, are shots in the dark when predicting their post-T brightness.

As for P/Halley during its 1986 apparition, it followed closely the lightcurve predicted for it that was presented by Bortle and Morris...one based on brightness activity observed during past apparitions. Thus, the comet was just about on the mark in regard to its brightness. It was the tail's poor performance that deviated markedly from early apparitions.

Hyakutake was indeed a dramatically more impressive comet with the unaided eye than Hale-Bopp, albeit not nearly as long lasting.

BrooksObs

#73 ericj

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Posted 05 August 2013 - 11:01 AM

Hi,

Mars and Comet C/2012 S1 ISON will be within two degrees of each other in the morning sky in September 2013 and within one degree of each other in October 2013.

I was using SkyMap Pro recently to get an idea of how high in the sky Comet C/2012 S1 ISON will be in the fall.

I noted that Mars and Comet C/2012 S1 ISON will be with two degrees of each other in the morning sky in September 2013 and within one degree of each other in October 2013. So using SkyMap Pro I generated sky maps as they may be helpful to observers attempting to locate the comet.

In addition I have included tables listing the phases of the Moon for September and October.

The first map shows the track of Mars and Comet C/2012 S1 ISON from September 15th through October 15th. Both Mars and Comet C/2012 S1 ISON are in the constellation of Cancer in September and are in Leo in October.

On the maps there are track marks for every five days. The track marks on the left are Comet C/2012 S1 ISON while the tracks on the right are Mars. You will note that over time they are getting closer to each other.

The second map below shows the approximate 4 degree field of view through my TMB 105mm with a TMB 40mm 2" Paragon of Mars and Comet C/2012 S1 ISON on September 15th. It indicates that both Mars and the comet should fit into the same field of view.

However at this point it appears that the comet will develop more slowly in the autumn sky than originally thought, and may not reach naked eye visibility until November.

On the other hand if you have access to dark skies and a larger aperture telescope or do astrophotography you may be able to use Mars as a guide to locating the comet.

Here is a link to the sky maps and tables listing the phases of the Moon for September and October:

http://ejamison.net/...nt_obs11.html#1

Clear Skies,

Eric Jamison

http://ejamison.net/index.html

#74 stevecoe

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Posted 05 August 2013 - 12:42 PM

Eric;

Thank you very much, this looks like an excellent observing opportunity. I plan to try some wide field imaging, maybe 200mm lens, and observing with the 16 inch. Lots to do.

Clear skies to us all;
Steve Coe

#75 HurricaneWhisper

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Posted 05 August 2013 - 08:46 PM

Is there a way to determine the best viewing location in terms of longitude and latitude?

Assuming lower 48 states locales only, nearest I can tell is that you want to be as far south as possible while still being in dark cloudless skies. I believe high elevation is a plus while unobstructed views of the horizion is a must.

I am basing this on the assumption of getting the comet to be as high in the sky as possible.

For me, I believe Big Bend Country in Texas would be the best viewing location due to southern latitude, high elevation, dark skies, lack of humidity, etc.

I also wonder what the best location globally is. Is there an optimum Latitude?

Panstaars was very low on the horizon when we viewed it and was basically chasing the sunset so closely that the dusk washed it out.






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