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C/2012 S1 ISON

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#151 hiro

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Posted 03 October 2013 - 05:35 PM

Their analysis is dependent on data gathered by others, brightness reports containing many errors by many persons in the world, and I could not find their accepted reports.

The facts in the history of the comet are as follows:

The length of the dust tail got longer in the past, mere 10 arcseconds in January 31, 2013, and 8 arcminutes in September 30, 2013. Earth distance got about half in the period, and the length got longer by 8x60/10/2 = 24 times in the past eight months. The length got longer very quickly recently, 4 arcminutes in September 16, 2013 and 8 arcminutes in September 31, 2013. The tail got longer by 2 times in the recent two weeks.

Halo was observed first on September 1, 2013 by Juan José González Suárez. I could image the green-tinted halo on September 16, 2013. The halo is another evidence of activity on the surface of the comet, which reached “frost line” in the period.

http://cometografia....s-2013-octubre/

Here is a report by real researchers of astronomy, Karen J Meech and others, which was submitted on August 25, 2013 and accepted on September 9, 2013. This is really nice report containing data gathered with Gemini North 8m scope.

”Outgassing behavior of C/2012 S1 (ISON) from 2011 September to 2013 June”
http://arxiv.org/pdf/1309.2688.pdf

Their last words were as follows.
“While it is unwise to make predictions about the brightness at perihelion when the comet is still far from the sun, especially when it will pass so close to the sun, the run out of these sublimation models show that the comet can still be quite bright at perihelion.”

#152 CygnuS

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Posted 03 October 2013 - 06:04 PM

All the uncertainty is fun, educational and exciting. Of course it will be a lot more fun if this thing really does make negative magnitudes.
I've been going through the special edition magazine put out by Astronomy magazine and I really like it.
There are several pages dedicated to October and also January but November and December have night by night break downs of the comet's behavior (and predicted behavior) It will certainly be interesting to see how their magnitude predictions come out.

#153 PGW Steve

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Posted 04 October 2013 - 01:11 AM

Here is a shot I took on the 27th.
Field is 17.3x13.1 arc minutes.

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#154 Rich (RLTYS)

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Posted 04 October 2013 - 05:20 AM

Looks good. :jump:

Rich (RLTYS)

#155 BrooksObs

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Posted 04 October 2013 - 08:12 AM

The recent images of Comet ISON have all been very nice and at first glance impressive, that is until one takes a moment to appreciate their scale.

From a more usual visual standpoint I would hasten to point out that the comet remains a disappointingly small and faint object considering how much closer it has drawn to the Sun over the past couple of months. A more typical comet might be anticipated to be an easy object for at least modest-sized amateur telescopes visually, if not in fact a faint binocular one at this point. However, Comet ISON's coma continues to subtend only a very small dimension in spite of its seemingly impressive photographic tail. At the same time it remains a rather challenging object to see clearly even in fairly large amateur telescopes. Now admittedly the comet's current place in the sky has it in the heart of the morning Zodiacal Light from Earth's vantage point and degrading its visibility, but this does not fully account for how unimpressive ISON appears visually.

On that note I will point out once again that Comet ISON continues to display an intrinsic brightness that is very close to bordering on the survival/non-survival line for comets of very all q at its projected intrinsic brightness. In some ways this seemingly might group it with the presumed behavior of the famous Southern Comets of 1880 and 1887 prior to their perihelia. Hopefully ISON will manage to "hold together" long enough for its nucleus to make it through perihelion and thereby offering the potential for it to develop an impressive tail before dawn in the earliest days of December, but....at this point I would advise observers to keep their fingers and toes crossed!

BrooksObs

#156 Tonk

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Posted 04 October 2013 - 10:25 AM

Of course it will be a lot more fun if this thing really does make negative magnitudes.


But you will not notice this as a) its only potentially this bright for a few hours around perihelion and b) it will be 1/2 to 1 degree from the sun when brightness peaks

The peak is sharp and of short duration

Example of the predicted light curve is here

http://www.aerith.ne...2S1/2012S1.html

#157 m00nless

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Posted 04 October 2013 - 11:21 AM

Is anyone observing the comet visually yet using a moderate sized telescope?

#158 Parkit

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Posted 05 October 2013 - 09:59 PM

I'm a bit confused. I thought ISON was supposed to be THE big deal starting right around .... now. The last issue of Astronomy magazine I have is from January of 2013 (renewed subscription last week, mostly because of this comet), and after looking closer at it's projected path (pg. 58-59) I can easily see that I'd have to be out at about 5:30am Central time just to TRY to get a glimpse of Comet ISON. It looks from the graphic in Astronomy magazine that the comet's path is through the Spring-Summer sky, and, well, it's not summer anymore. I'm thinking that if we're going to see anything, the best bet is after perihelion? Maybe mid-December?

#159 CygnuS

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Posted 05 October 2013 - 10:58 PM

Great image PGWSteve! Thanks for sharing it.
Parkit, Since your January edition, Astronomy magazine has backtracked a lot. At first they were saying it had a good chance of being the best comet in 400 years but things have changed.
I'm still hoping to get my first view of it on October 15 with my 10 inch SkyQuest Dob. I live in a dark location but have too many trees to the east so I hope I can get some advice from folks here as to whether or not it would be worth it to get up early and load my scope up and move it. I don't want to go to all that trouble if my chances of seeing it are very low.

#160 canukLX90

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Posted 06 October 2013 - 09:20 AM

Image taken this morning 5:30 - 6 AM
Azimuth 98 deg. Altitude 29 deg
7 X 3 min @ ISO 800 modded 450D and PowerNewt @ F2.8

A 30 second exposure did show the comet. Comet seems to be
developing nicely and fingers crossed it reaches naked eye
visibility in December/ January time frame.

PJ

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#161 Tonk

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Posted 06 October 2013 - 10:36 AM

The last issue of Astronomy magazine I have is from January of 2013 (renewed subscription last week, mostly because of this comet),


Which I suspect is precisly what they wanted to achieve.

There is usually no chance a prediction made 11 months before perihelion with a new first time visiting comet has any chance of having any accuracy. A good journalist would know this by doing the required research and looking at the success of historial long term predictions (Kohoutec anyone?) and not blithly following the initial hype that was thrown up only days after this comet was discovered.

Hence the backtracking after the comet has been observed over a much large portion of its orbit and its dynamic behaviour better understood.

At the time we were told it could be as bright as the moon without qualifying that this would be very brief (a few hours only) and very very close to the sun in the daytime sky

I don't want to go to all that trouble if my chances of seeing it are very low.


Factor in that it currently is around mag 11 but brightening every day

#162 Parkit

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Posted 06 October 2013 - 10:50 AM

Thanks for the replies, I figured that the early hype was exactly that. I'll wait a bit before I start looking for it in the 14" dob.

#163 kfiscus

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Posted 06 October 2013 - 04:14 PM

Found it easily on Oct.2 in my Z12. Looked like a slightly oval planetary nebula, both in terms of color and fuzziness. I couldn't pick up the tail, my observing buddy thought he got a glimpse of it. We've been cloudy ever since.

#164 Tonk

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Posted 07 October 2013 - 03:49 AM

I'll wait a bit before I start looking for it in the 14" dob


I would have thought a 14" would master a 11 mag object! However ISON is currently in the zodiacal light band which doesn't help

#165 hiro

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Posted 07 October 2013 - 09:37 AM

Hi again,

I could take new frames of the comet on October 5, 2013. It was in zodiacal light.

Posted Image

Data and original are here as usual.
http://www.flickr.co...oc/10131796815/

Posted Image

Data and original are here.
http://www.flickr.co...roc/10132557786

The comet looked still dark and small, thought it got activated much.

Thank you for looking.

#166 Dave M

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Posted 08 October 2013 - 09:08 PM

Nice shots Hiro..

#167 MessiToM

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Posted 08 October 2013 - 09:10 PM

Another nice photo ^

I have been either cloud or fog plagued for a week or two. I will wake up AGAIN at 5am to check for a clear low horizon.

#168 Mike B.

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Posted 08 October 2013 - 10:05 PM

Here's my first go at it:

Posted Image
Comet ISON, 2013-10-07. 24x120 sec @ ISO 800, TV-85 at F/5.6, IDAS-LPS, Canon T3 mod.

Even though I'm shooting through lots of bad LP and I had to cut a tree down to get the shot, ISON is doing well enough to produce a decent image even under those conditions.

#169 dyslexic nam

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Posted 08 October 2013 - 10:14 PM

^^^ very nice pic.

#170 MessiToM

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Posted 08 October 2013 - 11:38 PM

Cut a tree down for the shot! Lol that's great. Good pic!

#171 Tonk

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Posted 09 October 2013 - 04:50 AM

Even though I'm shooting through lots of bad LP and I had to cut a tree down to get the shot, ISON is doing well enough to produce a decent image even under those conditions.


Darn, I have to cut out 20 trees (not mine) and dig out a whole hillside and reroute a road. I won't get a photographic look in until post perihelion

#172 SporQ

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Posted 09 October 2013 - 08:30 AM

Cutting down trees just allows more LP in.

What magnification is the above photo? (This really should have been included. If a photo is worth posting, it deserves a caption).

#173 blb

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Posted 09 October 2013 - 08:46 AM

What magnification is the above photo? (This really should have been included. If a photo is worth posting, it deserves a caption).

Wow! Here is the caption he provided.

Comet ISON, 2013-10-07. 24x120 sec @ ISO 800, TV-85 at F/5/6, IDAS-LPS, Canon T3 mod.

All that needed to be included is included in it. I have never seen the magnification posted with any picture in a magazine or book. In fact he gives more information than most published photos. :help:

#174 John Wunderlin

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Posted 09 October 2013 - 09:57 AM

Cutting down trees just allows more LP in.


And also allows you to image an object that you otherwise couldn't image. I'd do the same, but my problem tree is in my neighbor's yard- they may say something if I cut down their tree. :grin:

#175 brianb11213

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Posted 09 October 2013 - 10:28 AM

my problem tree is in my neighbor's yard- they may say something if I cut down their tree. :grin:

Build an observing tower? :foreheadslap:






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