Comet 103P we have a rotation time

[NickH]

So, I was working on this at the weekend, and came up with a value of 19.75 hours (which I discussed at UCL with Dr Emaily Baldwin and Dr Paul Roche of Faulkes), but was not 100% confident of my calculations so erred between 16 and 20 hours (as people following my Facebook threads will have seen)

Toni Scarmato has now independently come up with a value of 19.59 hours, based on the Faulkes North data I and others have been gathering

Still not 100% sure, but it's close to the 16.6 hours which Hubble measured, and given that it's become more active with jets appearing, I hope, accurate

NASA saying it's now one of the most active comets they have seen

NASA Spacecraft Hurtles Toward Active Comet Hartley 2 - NASA Science

Nice pic...taken in fact with a 4" TMB and not a 2m behemoth

[Tim]

Excuse my ignorance, what does this mean Nick? The rotation bit? How long the thing takes to rotate on its own axis?

And is he likely to get bigger/brighter like the last one suddenly did?

[Tim]

Just running a few shots, its a lot brighter already than the last time I looked!

[NickH]

TJ

Yes, it's the time to rotate on its axis. Hubble had it pinned at 16.6 hours, so our value is close... and it's getting brighter, but vastly more diffuse

[QldLiz]

Is that fast for a comet Nick?

[NickH]

Not really, 73P had a rotation rate of 3-4 hours according to research on it, and Halley was 52 hours, so it seems pretty normal, but all of this is dependent of course on size, composition etc. What's interesting if the results we have deduced do pan out is the change from 16.6 hours measured by Hubble a few months back to this, now, a slowing down..

It's an interesting one to follow as obviously on Nov 4th, we're going to see this in superb close up, and get a lot more info

[QldLiz]

Thank you for that Nick, very exciting!!

[NickH]

CBAT from the IAU puts it at 17.6 hours...almost bang in the middle of my original posted (estimations of 16-20.. hours) and only 0.1 hours from the first calculation I posted on Oct 16th...(thank God for Facebook and evidence!)

chuffed!

>>>

The repeatability of the CN morphology is consistent with a

periodicity around 17.6 hours. Small differences in the morphology during

some cycles suggest that there may be a slight rotational excitation, probably

a low-excitation short-axis mode.

<<

[narrowbandpaul]

great work Nick!

very impressive stuff.

paul

[NickH]

Boring comet :-)

I think not...

Just working out if it went "pop" again a few days back...looks like it may have