(meteorobs) Ursids December 22

[stange34 at sbcglobal.net]

This will be an especially interesting opportunity for all of us.

YCSentinel


----- Original Message ----- 
From: "Jenniskens,Petrus M. (ARC-SST)[SETI INSTITUTE]" 
<petrus.m.jenniskens at nasa.gov>
To: <meteorobs at meteorobs.org>
Sent: 2007/12/19 18:38
Subject: (meteorobs) Ursids December 22


>
>
> URSIDS 2007
>
> We expect a significant shower on December 22, with a peak
> around 20 - 22.2 UT and a full-width at half peak intensity of
> about 2 - 8.5 hours (most likely around 5 hrs).
>
> It would be great if this prediction could be confirmed. The
> Moon is not favorable, but we hope that this does not discourage
> visual, video, and photographic observers. The outburst is best
> seen from Asia or Europe and by radio forward meteor scatter observations.
>
> Below is the CBET announcement with some of the same information.
>
> Peter Jenniskens
>
> (pjenniskens at seti.org)
>
> ---
>                                                 Electronic Telegram No. 
> 1159
> Central Bureau for Astronomical Telegrams
> INTERNATIONAL ASTRONOMICAL UNION
> M.S. 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, 
> U.S.A.
> IAUSUBS at CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
> CBAT at CFA.HARVARD.EDU (science)
> URL http://www.cfa.harvard.edu/iau/cbat.html
>
>
> URSID METEORS 2007
>     P. Jenniskens, SETI Institute, writes that he and his colleagues E.
> Lyytinen, M. Nissinen, I. Yrjola, and J. Vaubaillon (Jennniskens et al.
> 2007, JIMO 35, Dec. issue, in press) predict an outburst of Ursid meteors
> associated with the imminent return of comet 8P/Tuttle to perihelion.  The
> peak of the outburst is predicted at 20-22.2 hr UT on Dec. 22 (most likely
> 21h.4-22h.2), when the shower rate (ZHR) will be about 40-80 meteors/hr, 
> or
> 4-8 times the normal Ursid activity.  The outburst may last as short as 
> FWHM
> = 2 hr if dominated by dust trails that were ejected during AD 700-900, or
> as long as FWHM = 8.5 hr if older dust trails are involved.  Meteors 
> should
> radiate from a geocentric radiant of R.A. = 218.3 deg, Decl. = +75.5 deg
> (equinox 2000.0), with velocities of V_g = 33.52 km/s.  These results were
> derived by calculating the orbital evolution of meteoroids ejected by
> comet 8P in the period AD 300-1400; it was found that encounters with
> Jupiter at the ascending node of the comet orbit shortly after ejection
> move the meteoroids in mean-motion resonances that evolve the dust into
> earth-crossing orbits, creating a stream or filament that is elongated
> perpendicular to the earth's path.
>
>
> NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
>      superseded by text appearing later in the printed IAU Circulars.
>
>                         (C) Copyright 2007 CBAT
> 2007 December 10                 (CBET 1159)              Daniel W. E. 
> Green
>
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