Comet ISON News and Links - 2013

Comet ISON News and Links - 2013

Postby william-kowalczyk » Wed Jul 24, 2013 8:30 pm


June 13th: Spitzer Eyes Comet ISON
July 25th: Hubble Images ISON
July 29th: How to Contribute to Science: ISON Images
Aug 2nd: ..waiting for ison.. blog update
Aug 2nd: Comet ISON workshop videos posted

ISON comes out from behind the sun:

Aug 13th: CIOC Announcement of ISON Recovery Sky&Telescope blog
Aug 14th: An Amateur Star Geezer’s Account of His Comet ISON Recovery Imaging
Aug 16th: ISON's Oct 1st Mars Close Approach - MRO and Curiosity
Aug 17th: ...waiting on ison...Aug 17th update
Aug 19th: It's Alive!
Aug 28th: ...waiting on ison...Aug 28th update
Sept 2nd: Ready, Set, Observe! How to See Comet ISON In The Early Morning Sky
Sept 17th: ...waiting on ison...Sep 17th update

Took some time off for new arrival in the family and the government shutdown. Go government credit card :-)

Oct 9th: Comet ISON is doing just fine!
Oct 11th: ISON’s Chances for Survival 50/50
Oct 12th: ...waiting on ison...Oct 12th update
Oct 24th: Why does ISON look green?

Nov 1st/2nd prime weekend: HAS Darksite - Saturday morning viewing was very good and Sunday morning had many club members getting out of their cars to brave the cool air just before dawn to get thier first look at ISON. Great time to be a star gazer.

Nov 5th: What might happen to Comet ISON from here on out?

Any further updates will be added as new replies to this thread...

Below are some good links to get up to speed:

Perihelion & Distance: Continuously Updated
The Sky Live - ISON Tracker
Comet ISON Ephemeris
Comet ISON News
Comet ISON Atlas

ISON Updates from the NASA CIOC (Includes a science blog)
Sungrazer Comets Twitter Feed
Path of ISON- Video
Timeline of Comet ISON
NASA Comet News
HubbleSite - ISONblog
Comet ISON Toolkit
Skyhound Comet Chasing
The Comet ISON wiki
. . WAITING FOR ISON . . (Terrific blogger...huge segment on photographing comets)

Free interactive tools:

NASA JPL - Eyes On the Solar System
Solar System Dynamics: JPL Small-Body Database Browser: C/2012 S1 (ISON) Java required for applet to run orbital diagram and animations.
Great way to animate sungrazing comets with images from Stereo and SOHO satellites: JHelioviewer

Cool Videos:

An animation depicting the trajectory of comet C/2012 S1 (ISON)

ISON's Track:

[High Res 1920x1080]


[High Res 1920x1080]

Projected path of ISON from SOHO LASCO C3. Click image for the latest image:




Additional Sites:
IAU MPC Elements and Ephemeris for C/2012 S1 (ISON)
Heavens Above Comet C/2012 S1 (ISON)
NASA Solar System News
Comet ISON 2013
NightSkyInfo - C/2012 S1 (ISON)
ISON Infographic
Anticipated STEREO observations of Comet ISON
Havard Cometary Science Archive
Video: ScienceCasts: Comet of the Century
Video: ScienceCasts: Comet ISON Meteor Shower - Jan 12 2014
The BRRISON Mission

Please help keep this one going. It would be amazing if we can capture what HAS experiences as this high potential comet approaches the sun.
Last edited by william-kowalczyk on Wed Nov 27, 2013 4:34 pm, edited 64 times in total.
Bill Kowalczyk
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Re: Comet ISON News and Links - 2013

Postby william-kowalczyk » Sat Jul 27, 2013 9:12 am

Hubble press release:

July 25, 2013: In this Hubble Space Telescope composite image taken in April 2013, the sun-approaching Comet ISON floats against a seemingly infinite backdrop of numerous galaxies and a handful of foreground stars. The icy visitor, with its long gossamer tail, appears to be swimming like a tadpole through a deep pond of celestial wonders.

This photo is one of the original images featured on ISONblog, a new online source offering unique analysis of Comet ISON by Hubble Space Telescope astronomers and staff at the Space Telescope Science Institute in Baltimore, Md. For more on ISONblog, visit:

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Re: Comet ISON News and Links - 2013

Postby william-kowalczyk » Mon Jul 29, 2013 5:46 pm

I thought this was an interesting assesment by J. Bortle ( in Bortle scale):

In looking at the most recent photometric data, it would appear that
C/ISON's absolute magnitude (assuming a change in heliocentric brightness in
step with the typical 8.3 log r) is close to magnitude 7.5 currently.
Under normal circumstances this would make ISON similar to many modestly
bright (i.e. "average") comets seen in the past. However, with this comet's
exceedingly small perihelion distance the ultimate situation is less clear.

Comet Ikeya-Seki of 1965, with an absolute magnitude of 6.5 , appears to
represent the faintest major sungrazer/sun-skirting comet to have survived
perihelion essentially intact. The non-surviving sungrazing comets of 1880
and 1887 were "thought" to have absolute magnitudes of around 7.0-7.5 ,
although this might be open to question. Then there is Lovejoy's recent comet
that violated all the rules and was intrinsically quite faint, ultimately
classified as a member of the non-survival group. So...where will C/ISON fall?
This is really difficult to predict at the moment. However, I would like
to offer the following tentative prognostication.

Comet ISON will develop more slowly in the autumn morning sky than had been
initially hoped for. It will not actually attain naked eye brightness
until just a week, or two, before perihelion passage. By then it will already
be descending into the morning twilight. On perihelion day the comet may
attain -6 very briefly (hours) and be visually detected near the Sun using
great caution, then immediately begin to fade rapidly.

As the comet retreats from the Sun its head will be brighter than
magnitude +2 or +3 for just a few days, but it will be beginning to unfurl an
extraordinary long straight tail of considerable surface brightness, at least
initially. This tail could reach 30 or perhaps even 45 degrees in length a
week post-T, but its visibility with the naked eye will rapidly wane. The
tail's impressive visual show will last perhaps no more than a week to ten
days in total. Thereafter, like C/Lovejoy, ISON's photographic tail will
continue to lengthen and fade for some time. Concurrent to this the comet's
head will likely dissipate more-or-less in the same manner as did Lovejoy's,
with Comet ISON becoming a "Headless Wonder" by mid December, or very soon

I would anticipate that any further critical predictions of this comet's
future behavior will have to wait until at least early September.

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Re: Comet ISON News and Links - 2013

Postby william-kowalczyk » Mon Jul 29, 2013 6:30 pm

ISON's future as seen by the folks at the COIC:

As we gaze into our crystal ball...

This is the part everyone is most interested in; the part where we tell you that the comet will light up our bedrooms at night, and make the full moon blush with shame! Except we're not saying that, because that really won’t happen. But don’t lose heart because the reality, albeit uncertain, does still look very promising!

We’ve already said that comets are unpredictable, and this one will be no exception. The closer it gets to us, and the longer we observe it, the better the handle we’ll have on how it will behave. The question we’ve probably received the most is: “When will we know how bright ISON will be?”. Our answer: by August or September we should be able to paint a good picture of its expected behavior, so anything we say between now and then is uncertain, unknown and based on educated guesses. So, that disclaimer aside, let’s take a look at the possible outcomes for Comet ISON and consider three cases that are representative of the spectrum of reasonable outcomes for the comet.

Case #1: Epic Fail

First case is the worst case: Comet ISON is an “epic fail”, to use the popular vernacular. By this we mean that the comet enters into the inner solar system and simply fizzles out, perhaps by way of disruption or fragmentation. Why would it do this? Well, ISON is likely a very “fresh” comet on its first visit to the inner solar system. All of its volatile elements may be fully intact, and it may never have felt the intensity of the Sun’s radiation or gravitational stresses. If true, this could explain why ISON is already so relatively active while still so distant from us. Why is that bad news? Like a light bulb that shines a little too brightly, it may be releasing its ice, dust and gases at a rate that it can not sustain and could lead to it becoming structurally unstable, or simply vaporizing away. The ridiculously over-hyped Comet Elenin did just that, and that is just one recent example of which we have several. If ISON does fizzle, it could happen at any time later this year, whether it be months, weeks, or days from its perihelion, and under this circumstance would be unlikely to reach a brightness that would allow it to attain naked-eye visibility.

Case #2: Sizzle and Burn

Second possible case: we get a nice bright comet, that completely disrupts and vaporizes near the Sun. This is a middle-of-the-road outcome, and one that sees comet ISON brighten up through October and November, coming to perihelion in late-November as a bright comet, quite possibly creeping into negative magnitudes in mid-to-late November. Observers will be able to see it with telescopes, particularly in early-October, before it begins to get lost in the Sun’s glare later in October. In mid-November it will appear in our telescopes on the NASA STEREO and ESA/NASA SOHO satellites, likely saturating our detectors (which struggle with objects brighter than about magnitude zero). The comet peaks in brightness in the hours surrounding its perihelion passage but this tough little newcomer to the solar system begins to struggle as the intense solar radiation, and tidal gravitational stresses begin to take their toll, and in the hours following perihelion, the comet begins to dissipate. It may “outburst”, creating a large dusty plume (a la Comet Holmes), but lose its central nucleus. It may become visible as a diffuse object in the night sky, perhaps visible to the naked eye, but fading fairly quickly over the following weeks, and largely gone from all but the most powerful telescopes by early 2014.

Case #3: History in the Making

Third case: “the Comet of the Century”. We're almost hesitant to even describe this outcome because folks will jump all over this. Nonetheless, the possibility does indeed exist that Comet ISON becomes one of the more spectacular comets in living memory. In this circumstance, the comet will brighten steadily and quickly through September, becoming easily visible with binoculars and perhaps even naked eye in some locations by early-to-mid October, particularly for Northern Hemisphere observers. It is gradually lost in the Sun’s glare in late October, but remains bright enough that skilled observers can follow it with their telescopes until a week or so preceding perihelion. In late November, it enters our spacecraft imagers, overwhelming the detectors and pushing us to the limits of our shortest exposure times to avoid saturation. In the day-or-so before perihelion, it brightens by orders of magnitude as the sunlight illuminates its long dusty tail. It may briefly peak near magnitude -8 or -10, not brighter than a full moon (and certainly NOT bigger than the full moon!), but is visible in broad daylight to careful observers who block the sunlight with their hand or the edge of a building. After perihelion, it emerges from the Sun’s glare as a large, bright comet, maybe still magnitude -3 or -4. At this time it should be sporting a very long dusty tail that stretches far across the night sky, quite likely reminiscent of that of its (alleged) analog, C/1680 V1, or the great Kreutz Sungrazer Ikeya-Seki . Northern hemisphere observers will have the best view, but even those in the Southern Hemisphere will get to enjoy the spectacle for several weeks, into 2014, as the comet slowly recedes away.

In conclusion...

We hate to belabor a point but these are theorized outcomes that represent parts of an entire spectrum of possible outcomes. The actual behavior of Comet ISON could fall anywhere within this regime, and have one or more facets of the above. That is, fragmentation/vaporization could happen at any point or not at all, and would be completely irrespective of its brightness at the time. Comets are notoriously unpredictable, and this one is one of the least predictable in a very long time. But regardless of the outcome, the build-up, anticipation and excitement already makes it more than worthwhile!
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Re: Comet ISON News and Links - 2013

Postby william-kowalczyk » Thu Aug 01, 2013 10:57 am

Live stream of the workshop today and tomorrow:

Livestream URL:

Here is the agenda

...and if you are like most folks that have a day job, the different discussions are being posted for replay.
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Re: Comet ISON News and Links - 2013

Postby william-kowalczyk » Thu Aug 01, 2013 12:31 pm

Here is a listing of planned ISON observation times using various solar observation assets:

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Re: Comet ISON News and Links - 2013

Postby william-kowalczyk » Mon Aug 05, 2013 10:05 am

Comet ISON Observing Campaign (COIC) workshop videos are now available.

Very high quality and beyond informative.

Day 1

Day 2
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Re: Comet ISON News and Links - 2013

Postby william-kowalczyk » Fri Aug 16, 2013 9:54 am

Bill Kowalczyk
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Re: Comet ISON News and Links - 2013

Postby Guest » Fri Aug 16, 2013 1:57 pm

I cant wait for this comet to get here. All this nova hunting is great practice. Thanks for all the great info!

Re: Comet ISON News and Links - 2013

Postby rene-gedaly » Sun Sep 01, 2013 4:30 pm

Thank you, thank you, Bill, for this great info. I'm only now starting to seriously map out a plan to follow ISON and this is a treasure. You're pretty busy these days getting ready for the baby boy--you are going to let us know when it happens, right?--so thanks for the foresight and sharing it all with us.
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