Electronic Telegram No. 2064
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
M.S. 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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CBAT@CFA.HARVARD.EDU (science)
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LEONID METEORS 2009
     Editor's note:  this text replaces that on CBET 2046.
     P. Jenniskens, SETI Institute; and J. Vaubaillon, P. Atreya, and F.
Vachier, IMCCE, Paris, observing from the National Observatory of Nepal,
report that the Leonid shower (cf. CBET 2019) did show enhanced rates.  In
a 40-min clear-sky interval centered at Nov. 17d23h25m UT, the Leonid rate was
ZHR = 56 +/- 16 meteors.  G. Barentsen, International Meteor Organization,
analyzed 3756 visually observed Leonids by 107 observers; from 1670 Leonids
observed under sky limiting magnitudes in excess of 5.0, he found an average
population index of chi = 1.9 +/- 0.4.  Based on this, he calculated a peak
activity of ZHR = 101 +/- 8 at Nov. 17d20h19m +/- 8m UT, with a FWHM of 4 +/-
1 hr.  Alternatively, the reported rates can be interpreted as composed of a
1-day-wide filament component with peak ZHR = 25 +/- 5 meteors
(magnitude-distribution index chi = 1.9) at solar longitude 235.35 deg (Nov.
17d17h UT), and one or two narrow peaks centered on 235.50 +/- 0.01 deg and
235.67 +/- 0.03 deg (equinox 2000.0), with FWHM = 0.08 and 0.12 deg and peak
rates of ZHR = 60 and 20/hr.  Presumably, these were caused by the encounters
with the 1466 and 1533 dust trails of comet 55P/Tempel-Tuttle.


NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2009 CBAT
2009 December 2                  (CBET 2064)              Daniel W. E. Green