29P early hours of 23rd November
Peter Tickner
(23 Nov 2020 01:08 UTC)
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Re: [BAA Comets] 29P early hours of 23rd November
Nick James
(23 Nov 2020 07:14 UTC)
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29P 22nd November hints of coma features
Peter Carson
(23 Nov 2020 16:53 UTC)
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Re: [BAA Comets] 29P early hours of 23rd November
Richard Miles
(23 Nov 2020 17:55 UTC)
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Re: [BAA Comets] 29P early hours of 23rd November Nick James (23 Nov 2020 18:12 UTC)
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Re: [BAA Comets] 29P early hours of 23rd November
Richard Miles
(23 Nov 2020 19:00 UTC)
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Re: [BAA Comets] 29P early hours of 23rd November
Janice McClean 1
(24 Nov 2020 09:33 UTC)
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Re: [BAA Comets] 29P early hours of 23rd November
Richard Miles
(23 Nov 2020 17:51 UTC)
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Re: [BAA Comets] 29P early hours of 23rd November Nick James 23 Nov 2020 18:12 UTC
Richard, Thanks. Could you explain a bit more about the characteristic Pacman shape that we are seeing? Presumably the eruption is effectively an impulse and the material then expands almost symmetrically in a hemisphere above the surface. The coma expansion rate is 200 m/s or so which is an order of magnitude or more times the escape velocity so I would expect most of the material to travel away in straight lines so we would see an expanding hemisphere from some external angle. I don't see how that causes the shape we actually see. I know I can probably go and read your Icarus paper but a short summary would help! Nick On 23/11/2020 17:55, Richard Miles - rmiles.btee at btinternet.com (via baa-comet list) wrote: > Nick - Great image showing the discontinuity between the star-like > pseudonucleus and the ever-expanding visible coma. > > No joy with 2.0-m images due to bad weather. > However, provided you build the SNR as you have with a longish > time-series, your images can provide data almost as good given suitable > seeing and focus. This becomes increasingly the case as the coma expands > because amateurs have the luxury of sitting on a target for a long time > whereas access to the 2.0-m is only for a limited few minutes. At least > we got a good result with the FT South just 19 hours after the outburst > started - that's where the 2.0-m really scores well.