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Comet ISON update!

JB80

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allcart

allcart

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I agree. It does seem somewhat dimmer now. I'm not feeling optimistic.

i haven't had a chance to see it in the sky yet and it will be a week or more before I can get it from my location, but it looks like it will be a bit on the faint side by then.

Still keeping my fingers crossed though.

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gkec

gkec

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You have to be careful with interpreting images.  jpeg compression on images can and often does introduce artifacts. fits files for C2 and C3 are available for image analysis.  

Also the nucleus is a lot smaller than the white blob that is perceived  as the comets head.  This is know as the coma and is the stuff coming off which will become part of the tail in due course.

The brightness of the comet is also affected by the phase angle. This is the angle between the Sun and the Earth as seen from the comet.  This diagram shows what is happening in 3D.

http://www.mattastro.com/ison/interactive.html

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Special K

Special K

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I came off the beach with a good Idea of what I am doing if YKW carries on out in one clump over the next few days, and looked

at Lasco to see it is still hanging in there (just) and still within the feild of view.

This is time well spent as it will make it easier for the next session. I needed to know where on the horizon the sun is actually rising and though I didn't see that due to cloud I've got a good handle now. Horizon at the new site is a good flat one but with a few short distinctive landmarks that come in handy. Hope you get a good look in.

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mjpfc

mjpfc

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Just looing a a sequence of the lasco C3 images , Ison dimmed significantly as it left the area of the sun yesterday but it's dimming through

this morning has been a bit of a shocker.  The worst thing is it's dimming- in comparison to its own outflows which (to me, looking at the pics)

have not dimmed anywhere near as much as the coma has.

Oiz'll be out on the beach tomorrow morning but I am not expecting to see anything until it is up in darker skies at least may be after around the 7th?

Still, stranger things have happened, especially with Comets, and pretty regularly with this one.

Hoping it gets to 20 degrees up and does a "Holmes" before it goes,     Mick

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The Beast

The Beast

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On a more positive note I really enjoyed following ISON's ride around the Sun on the internet. All these great spacecraft images. This forum was fab. Internet astronomy - great! Instead of clouds the only problem is unresponsible servers / latency.

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Andy_E

Andy_E

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On a more positive note I really enjoyed following ISON's ride around the Sun on the internet. All these great spacecraft images. This forum was fab. Internet astronomy - great! Instead of clouds the only problem is unresponsible servers / latency.

I feel exactly the same. It's been a great ride despite the fact we probably wont get to see the end result.

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mjpfc

mjpfc

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Just looked at the 15:42 Lasco C3 image, the poor thing looks to be in bits before it made it out of the FOV.

I have'nt maginfied it yet but it looks to be spread about the place now with no core left.

.

So long and thanks for the ride Ison

Now what's LJ Up to........Mick.

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AndyPandy

AndyPandy

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It does look like a diffuse smear.

However there could be a lot of debris there and while it may not and probably won't be an active comet in the next week or two there could still be some interesting phenomena to view, whether in binoculars or a scope if there is forward scattering from the debris.

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JB80

JB80

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http://www.mpg.de/7621979/winged-comet

"The dust tail of the comet is now divided into two parts," explains Hermann Böhnhardt from the Max Planck Institute for Solar System Research. According to Böhnhardt, the part of the tail that is pointing towards the sun consists of dust particles, which were released significantly before the comet's Perihelion passage – i.e. prior to reaching the closest point to the sun.

The other part, however, appears to contain more recent material: It was released when ISON passed the sun and suggests that at least part of the nucleus still existed and was active at that time.

The Max Planck researchers base their assessment on computer simulations in which they model the shape of the dust tail. "If we assume in our calculations that the comet has emitted dust at Perihelion, we can reproduce the current images quite well," says Böhnhardt.

Only the LASCO images from tomorrow, Saturday, will allow an analysis of whether a nucleus exists. The dust that ISON may release today needs a few hours to make its way into the visible tail region, where it can be detected. Whether the comet nucleus was still intact at Perihelion or continued its flight as a small fragment or as collection of chunks is not yet clear.

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