[X] My Assistant

[Mongo]

Dr. RawheaD @RawheaD 7h

@CometISONnews Has anyone calculated the magnitude of ISON at this point?

Comet ISON @CometISONnews 6h

@RawheaD The last estimate I saw was around mag 1 @ 11/29 @ 0:23 UT

[craigmcg]

NASA website is still saying that ISON fizzled out as of 8:00am EST.

The combination of US holiday and "erratic" ISON behavior are making for some entertaining media.

Oh, and most of the ISON sites seem to be overloaded...

[Gerald]

Quick, someone smarter than me please do the math and see how elongated it became from traveling that fast.

For 0.125% of the speed of light I get 1-sqrt(1-(0.00125)²) = 781 p.p.b. or 7.81e-7as relativistic length contraction. (That's 0.781 mm per kilometer.)
The relativistic mass increase is 0.781 grams per metric ton.
Time dilation (only the part imposed by speed) is about 26.7 seconds per year; ok, ISON wouldn't survive that year as a comet.

[ElkGroveDan]

Thanks Gerald. Miniscule, but fascinating nonetheless.

[Paolo]

a minuscule effect, but an atomic clock traveling on ISON yesterday would still clearly be out of synch with one "at rest"

[Mongo]

Newest C3 image:

Attached thumbnail(s)

 

[scalbers]

This YouTube video shows a continuing apparent brightening trend since perihelion from C3. I wonder though if vignetting (and if there is any radially dependent image processing) might alter this interpretation.

The C3 image shown below (taken at 15:24UTC) saturates over a fairly large area. Thus it could have a relatively high total brightness even without producing any bleed lines.



Here is 14:55UTC view (top of image) from STEREO Behind COR2. This vantage point looks to be more in the plane of the comet's orbit.

[Mongo]

ISON on SDO (AIA 193):

Attached thumbnail(s)

 

[MahFL]

It's interesting how the tail does not point away from the Sun, like the convention images show. Is that because it's moving so fast at that point ?

[Mongo]

It's interesting how the tail does not point away from the Sun, like the convention images show. Is that because it's moving so fast at that point ?

I recall the same thing happened with comet Lovejoy when it was at perihelion. These comets are moving FAST at that time, and the tail has not yet had time to be blown very far away from the Sun.

[Mongo]

A very nice animated GIF of ISON. This is compiled from the "beacon" images, the full-resolution images should be down within a few days. The rotation of ISON's nucleus, as implied by its jets, is very evident after perihelion.

To me, this looks like very solid evidence that some portion of the nucleus has survived.

[ElkGroveDan]

ISON on AIA 193:

Damn that is an amazing image! I hope there's a high-res version somewhere.

[Paolo]

It's interesting how the tail does not point away from the Sun, like the convention images show. Is that because it's moving so fast at that point ?

dust tails have lot of inertia, so they usually don't point exactly away from the Sun. gas and ion tails on the other hand always do

[Mongo]

My best guess as to why ISON is so odd-looking right now. It looks to me like ISON is currently spewing out debris at a ferocious rate, with very high velocities compared to a "regular" comet. Considering how close ISON got to the Sun, with temperatures on parts of the nucleus soaring well above those needed to vaporize rock, this is not a huge surprise to me. So instead of the released dust staying relatively near the nucleus, forming a fairly symmetrical coma and gradually being blown outwards from the Sun to form a typical tail, we are seeing several huge jets of debris acting like an out of control firehose, spraying away from the nucleus at much higher speeds than normal and forming a very extended cloud.

I look forward to seeing what ISON looks like in the coming days and weeks.

[elakdawalla]

I've been having trouble figuring out when the higher-resolution images will be coming down from the STEREO spacecraft to replace the lower-resolution ones. Does anybody know, or can point to some kind of schedule?