Comet ISON : Realtime Image and Info 2013

Hi-res images from Dec 1st are up: stereo-ssc.nascom.nasa.gov...

ISON's remnant is very dim, and getting dimmer.

reply to post by wildespace

Here's a taste of what is to come. It's the Beacon data of course, but it shows the progressive loss of cohesion and brightness.

reply to post by ngchunter


Thanks mate. Looks like ISON's remnant disappears almost totally from the view? What does "BEACON" mean?

~~~

As an update to the thread, here's the latest hi-res image, from Dec 02:

And my time-lapse:

Latest hi-res image from STEREO-A (Dec 03) and the updated timelapse. ISON's remnant is barely visible.



By the way, I looked at the "fits" images from secchi.nrl.navy.mil... using FITS Liberator for CS2, but I can't see any trace of ISON in them (or the CMEs, for that matter). Am I doing something wrong?

(Dec 01 00:07:00)


A slight hint of ISON shows if I stretch contrast madly:


Could any astrophotography buffs here please post better images from "fits", where you can see ISON and CMEs?

Comet ISON was a really small one, around 1 km in diameter, perhaps even less. No wonder it broke up! Here's the assesment of some scientists using the Mars Reconnaissance Orbiter's images of ISON as it passed by Mars (emphasis mine):

COMET C/2012 S1 (ISON)
W. A. Delamere, Delamere Space Sciences; A. S. McEwen, Rod Heyd, and Sarah Mattson, University of Arizona; J.-Y. Li, Planetary Science Institute; and C. M. Lisse, Applied Physics Laboratory, Johns Hopkins University, report detection of comet C/2012 S1 using the Mars Reconnaissance Orbiter's High Resolution Imaging Science Experiment (HiRISE) on Sept. 29-Oct. 2 UT. The comet was detected in all five orbits (ten pointings) of MRO, with the signal-to-noise ratio increasing as the comet approached Mars and the phase angle of the observations rose from 47 to 89 deg. The authors find total V-band magnitudes of 16.2, 16.5, 16.7, and 16.5 in the 0".2 aperture at phase angles of 47, 47, 51, and 51 degrees for the first four observations. At closest approach, the HiRISE pixel scale at the comet was 13 km. Assuming all the observed flux to be due to scattered sunlight from the surface (noting that dust from the inner coma dominates the higher-phase-angle observations) and assuming a nucleus surface with an albedo of 0.03 with an adopted nucleus phase law of 10**(-0.016*phase angle), the authors find upper limits for the nucleus diameter of 1.25, 1.12, 1.05 and 1.12 km for the first four observations, with phase angles of 47 and 51 degrees for the broadband red filter. Similarly for the narrower blue-green filter, the upper limits are 1.25, 1.15, 0.95 and 1.12 km.

Note that those are upper limits to ISON's size, so in fact it could have been something like 900 meters in diameter.

This assesment corresponds to one amateur astronomer's calculations, presented below (column "Rcomet (m)" represents radius of ISON's nucleus in meters):


So next time some crank Youtube video tries to tell you that a comet is gigantic, keep in mind that there are real experts out there doing real science, measurements and calculations.

To round my post up, here's the latest hi-res STEREO-A HI1 image of ISON, from Dec 04: stereo-ssc.nascom.nasa.gov...

ISON's remnant is hardly brighter than the nebulosity around the Pleiades, according to amateur astronomer Ian Musgrave. By the time earth telescopes can see it it will be fainter still.
(The comet visible at the bottom of the image is Encke. It might be just image processing artifact, but to me it looks like it's got fainter and is perhaps losing its life too)

wildespace
By the way, I looked at the "fits" images from secchi.nrl.navy.mil... using FITS Liberator for CS2, but I can't see any trace of ISON in them (or the CMEs, for that matter). Am I doing something wrong?

(Dec 01 00:07:00)

A slight hint of ISON shows if I stretch contrast madly:

Could any astrophotography buffs here please post better images from "fits", where you can see ISON and CMEs?

You need to subtract the solar glare to have any hope of seeing ISON's faint remnants at all. It's interesting to note that such processing isn't even necessary at all to see ISON in the pre-perihelion images - just gives you an idea of how much dimmer the remnants are than the original comet. Anyway, I usually do one of two things; either I stack images from a previous day using a median combine setting to create a calibration frame that I subtract from each of the current frames, or I use PixInsight's dynamic background subtraction tool to create a pseudo-flat field image to flatten the background. The latter works for any image and any situation, so it's more flexible and useful for cases where the spacecraft rolls to some new attitude to perform an observation and appropriate frames from a previous day are not available. The disadvantage is that it generally doesn't get all of the solar glare removed, so CME's and comets near the sunward side are harder to see. The former works well most of the time though. Here are some examples using the beacon images and the first method (previous day median combine calibration).
Pre-perihelion:

Post-perihelion:

Hi all! And Mr Ngc..how you all feel about Ison..very great journey? Very mysteryous journey? Epic? Yes it is i think!
I am very sad when Nasa say Ison dead, but i was not sure about that, then ta da he alive! And give us much more question abut this great comet..

Anyway very much tq from me, tq for everything you all my beloved friend and mentor..adviser and my pal..i love you all

reply to post by cheesy


Thanks a lot for your Ison threads. I was watchin like a hawk. Maybe we will get another chance to admire another comet soon. I was waiting for Ison since it was announce last year. I'm sad but the show must go on.
Did you hear about the expected meteor shower on May of next year?

cheesy
Hi all! And Mr Ngc..how you all feel about Ison..very great journey? Very mysteryous journey? Epic? Yes it is i think!

I am very sad when Nasa say Ison dead, but i was not sure about that, then ta da he alive! And give us much more question abut this great comet..

Anyway very much tq from me, tq for everything you all my beloved friend and mentor..adviser and my pal..i love you all

I feel that ISON is a massive disappointment on the scale of Kohoutek and shows us once again why the media shouldn't hype up these comets long before they ever reach perihelion. ISON is as dead as a dead comet can be. It appears that all that remained after periehelion was a cloud of dust and debris which gave false hope to many and has generated multiple headaches for me.
spaceweathergallery.com...
spaceweathergallery.com...
Now it continues to serve as a distraction from a comet that's actually quite nice, comet Lovejoy, which has been outshining ISON for most of the last month or so with a brief exception near ISON's end. I was actually told the other day, "who cares about Lovejoy?" I can make almost any video I want about ISON and by default it will generate far more hits than if I made a video about Lovejoy, even though Lovejoy is turning out to be a much more consistent performer as a comet.

reply to post by wildespace
whats that white smudge in the bottom corner of your last image?

ngchunter

cheesy
Hi all! And Mr Ngc..how you all feel about Ison..very great journey? Very mysteryous journey? Epic? Yes it is i think!

I am very sad when Nasa say Ison dead, but i was not sure about that, then ta da he alive! And give us much more question abut this great comet..

Anyway very much tq from me, tq for everything you all my beloved friend and mentor..adviser and my pal..i love you all

I feel that ISON is a massive disappointment on the scale of Kohoutek and shows us once again why the media shouldn't hype up these comets long before they ever reach perihelion. ISON is as dead as a dead comet can be. It appears that all that remained after periehelion was a cloud of dust and debris which gave false hope to many and has generated multiple headaches for me.
spaceweathergallery.com...
spaceweathergallery.com...
Now it continues to serve as a distraction from a comet that's actually quite nice, comet Lovejoy, which has been outshining ISON for most of the last month or so with a brief exception near ISON's end. I was actually told the other day, "who cares about Lovejoy?" I can make almost any video I want about ISON and by default it will generate far more hits than if I made a video about Lovejoy, even though Lovejoy is turning out to be a much more consistent performer as a comet.

i feel it too sir, very sad..but TQ so much to you sir for your Great2 Image from your own telescope, i am very counting on you that time, very greatful for you..