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C/2012 S1 (ISON)

Posted: March 18th, 2013, 4:54 pm
by Christopher K.
Robert Naeye and company are being cautiously optimistic about the upcoming apparition of ISON. Discovered in September 2012, ISON is the focus of some predictions will state it will achieve the brilliance of Venus (or become even brighter!) for a short while, around the last week in November 2013.

ISON will cross from Gemini to Auriga between 11pm 20 March and 1am 21 March CDT. The Starry Night Pro Plus lists its current magnitude as 15.2. Due to the tilt of its orbit with Earth's ISON will "retrograde" back into Gemini around 25 April.

More information:
April 2013 Sky & Telescope, p. 6.

NOTE: See the "New Comet will Light up the Night Sky!" thread for the first postings on ISON.

Re: C/2012 S1 (ISON)

Posted: June 10th, 2013, 9:55 pm
by Christopher K.
At this time ISON is about one-and-a-quarter degrees northwest of 47 Geminorum. From 12 July to 17 July it will lie fewer than five degrees from the Sun. Around 31 July/1 August it crosses into Cancer. I am hopeful about the show this object will present to Earthlings.

Re: C/2012 S1 (ISON)

Posted: June 16th, 2013, 10:01 pm
by Christopher K.
John Bortle predicts the best morning viewing dates for ISON to be 10 December to 14 December. He also predicts the tail will be at least ten degrees long a few days after perihelion.

On 1 December the thin crescent Moon and Mercury will form a diagonal line with ISON, but the sky wll be quite bright by the time ISON reaches the horizon at about 6:10am.

More information: ... 08441.html

Re: C/2012 S1 (ISON)

Posted: August 9th, 2013, 12:58 am
by Christopher K.
On 10 April the Hubble imaged Comet ISON. Estimates at that time were for a nucleus much smaller than expected, considering the comet's current activity. The coma is almost 5000 kilometers across--wider than Australia.

At this time (9 August) ISON is up with the Sun, in Cancer. By 6 September it will be twelve degrees up in the east at 5am CDT. However, Gary Kronk says It is not currently observable visually except to highly experienced observers using large telescopes from a dark site. He predicts a magnitude of ~12.1 for the beginning of September.

Note at:
Astronomy, August 2013, p. 9

More information: ... -view.html

Re: C/2012 S1 (ISON)

Posted: September 1st, 2013, 8:41 pm
by Christopher K.
On 27 September, Comet ISON should be getting as close to Mars as it will during this trek toward the Sun. The Starry Night is predicting a very dim magnitude of 11 for ISON at that time.

At 4:45am on the 27th, Mars will be sixteen degrees up in the east, in the constellation Leo. At 5:30am it will be twenty-six degrees up.

Re: C/2012 S1 (ISON)

Posted: October 18th, 2013, 12:37 pm
by Tom
One report that ISON could likely survive its encounter with the Sun.

Re: C/2012 S1 (ISON)

Posted: November 8th, 2013, 9:19 pm
by Christopher K.
Kalmbach has released Great Comet of 2013 about ISON. It contains a brief introduction to comets, an overview of "great comets" in history, an article on imaging ISON with a camera, and (for November and December) a day-to-day planner.

Re: C/2012 S1 (ISON)

Posted: November 15th, 2013, 4:15 pm
by Christopher K.
Comet ISON has brightened considerably in the past forty-hours according to many reports, though not all. Alan MacRobert is calling it "a popsicle comet with a round, sharp-edged, bright green head and a long, thin, dim tail".

Below are the times at which ISON will reach ten degrees altitude in the Baton Rouge sky, together with magnitude estimates.
16 November: 4:39am / magnitude 6.3 [3˚14' S of Theta Virginis]
17 November: 4:50am / magnitude 6.0 [1˚56' WNW of Spica]
18 November: 5:01am / magnitude 5.8 [1˚19' E of Spica]
19 November: 5:13am / magnitude 5.5 [0˚53' WSW of 86 Virginis]

As one can see, ISON "overtakes" Spica this weekend.

Ignacio Ferrin is predicting that comet ISON will disintegrate; his speculation is based on similarities between ISON's current behavior and that of two others (Tabur of 1996 and Honig of 2002) which did indeed break up.

More information:
Great Comet of 2013 (Kalmbach Publishing) ... 93451.html

= = = = = = =
Sky & Telescope and Celestron are sponsoring a Comet ISON photo contest. Amateurs can enter submissions until 11pm CST on 31 December. The finalists will be posted online on 8 January, and the public can vote on the finalists' entries until 22 January. The winners will be announced in the April 2014 issue of S&T.
First prize, Celestron 8" EdgeHD Telescope with Advanced VX Mount and Skyris 274M Camera
Second prize, Celestron Cometron 114AZ Telescope
Third prize, Celestron Cometron 12x70 Binocular

More information:

Re: C/2012 S1 (ISON)

Posted: November 19th, 2013, 12:26 am
by Christopher K.
At this time Comet ISON is about magnitude 5.1.

Below are the times at which ISON will reach five degrees altitude in the Baton Rouge sky, together with magnitude estimates.
19 November: 4:48am / az 108˚ / magnitude 5.1 [0˚55' SW of 86 Virginis]
20 November: 5:01am / az 110˚ / magnitude 4.8 [2˚50' NE of 85 Virginis]
21 November: 5:14am / az 111˚ / magnitude 4.5 [3˚19' SW of Lambda Virginis]

One can still probably use Spica to find ISON this morning. After 21 November it will be increasing difficult to see ISON due to extremely low altitudes and twilight.

More information:

Re: C/2012 S1 (ISON)

Posted: November 21st, 2013, 3:54 pm
by btoman
I posted previously on this subject, but it appears there was some sort of error as my post doesn't exist. I'll follow through more on this one.

I tried to spot ISON Wednesday morning. Got up just before 5AM and got my stuff ready. I looked and looked, but just wasn't able to see it. It's just not getting high enough from my location to see before the Sun gets too bright. I'm starting to doubt it exists, too :)

On the bright side, I spotted Lovejoy for the second time. This time I did one of my awful sketches and documented the time and all. One more night and I can add it to my Comet Hunters Club list. (Of course, it's supposed to be nasty weather for the next few days so that is not helping.)