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Date: Mon, 16 Nov 2009 23:33:43 +0100 (CET)
From: Lucia
To: sky@titan.physx.u-szeged.hu
Subject: CBET 2019: 20091116 : LEONID METEORS 2009


                                                   Electronic Telegram No. 2019
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
M.S. 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
CBAT@CFA.HARVARD.EDU (science)
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LEONID METEORS 2009
      P. Jenniskens, SETI Institute, reports that the earth is predicted to
encounter the 1466 and 1533 dust ejecta of comet 55P/Tempel-Tuttle on 2009
Nov. 17d 21h43m-50m UT.  This may result in a brief (about 1 hr) duration
outburst of Leonid meteors with peak Zenith Hourly Rate, ZHR, > 100 meteors
per hour.  The best viewing will be from sites in mid-Asia, including China,
Indochina, India, Nepal, Mongolia, and Indonesia.  Initial peak-rate
predictions of ZHR = 5000 meteors per hour (Jenniskens 2006, *Meteor Showers
and Their Parent Comets*, Cambridge Univ. Press, p. 631) have since been
adjusted downward to reflect the results from more-recent observations of
55P´s older dust trail encounters.  However, peak rates critically depend on
the exact position of the 1533 dust trail, which is uncertain because of the
unknown orbit of the comet in 1533 and because the trail now moves rapidly
by the earth at the time of the predicted Leonid meteor outburst.
      The forecast by (1) J. Vaubaillon and P. Atreya (I.M.C.C.E., Paris),
Jenniskens, and J. Watanabe and M. Sato (National Astronomical Observatory
of Japan) is summarized below and compared to results by (2) M. Maslov,
Novosibirsk, Russia (two predicted peaks for each of the two trails); (3)
by D. Moser and B. Cooke, NASA Meteoroid Enivronment Office; by (4) E.
Lyytinen and M. Nissinen, Helsinki, Finland (2009, WGN 37, 122-124);
and by (5) D. Asher, Armagh Observatory (also two predicted peaks for the
1466 trail).  The miss distance is positive if the dust trail is outside
the earth´s orbit, and negative if inside the earth´s orbit.

1533 trail (14 revolutions old, center just outside of the earth´s orbit):

Source:               (1)          (2)           (3)        (4)        (5)
Peak times Nov. 17d  21h50m    21h55m, 21h16m    22h30m    21h44m     21h15m
Solar long., deg    235.550     235.550,        235.577   235.545    235.525
                                   235.522
miss dist., AU       +0.00053    +0.00044,        --         --       +0.0005
                                    +0.00039
ZHR, meteors/hr      80          65, 10          80         60          --
Duration, hr          1            --           < 1          4          --
R.A., deg           154.31      154.3             --         --         --
Decl., deg          +22.93      +22.9             --         --         --

+++

1466 trail (16 revolutions old, center just inside of the earth´s orbit):

Source:               (1)          (2)           (3)        (4)        (5)
Peak time Nov. 17d   21h43m      20h53m,          21h31m     20h53m   21h20m,
                                   21h39m                               22h00m
Solar long., deg    235.545     235.506,        235.536    235.51     235.528,
                                   235.538                               235.556
miss dist., AU       -0.00045    -0.00076         --         --        -0.0011,
                                                                         +0.0009
ZHR, meteors/hr     115          39             200         60           --
Duration, hr          1             --            2          8           --
R.A., deg           153.92          --            --         --          --
Decl., deg          +22.09          --            --         --          --

According to Vaubaillon, weaker activity may occur from the 1567 trail (Nov.
17d07h27m UT) at ZHR around 25 meteors/hr and from the 1102 trail (Nov.
18d03h29m UT) at ZHR = 10-50 meteors/hr.  Maslov predicts the peak of the
filament around Nov. 17d09h UT, with peak rates of ZHR = 25-30 meteors/hr.
To calculate the expected rate from a specific location, go to website URL
http://leonid.arc.nasa.gov/estimator.html.
      Online web sources are given below.
(1) J. Vaubaillon et al.:
http://www.imcce.fr/en/ephemerides/phenomenes/meteor/DATABASE/Leonids/2009/
(2) M. Maslov:
http://feraj.narod.ru/Radiants/Predictions/Leonids2009eng.html
(3) D. Moser and B. Cooke:
http://www.nasa.gov/pdf/372657main_2009LeoVisibility_Public2.pdf
(4) E. Lyytinen and M. Nissinen:
http://lists.meteorobs.org/pipermail/meteorobs/2008-December/009634.html
(5) D. Asher:  http://www.arm.ac.uk/leonid/


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

                          (C) Copyright 2009 CBAT
2009 November 16                 (CBET 2019)              Daniel W. E. Green