[IAUC] CBET 2862: 20111016 : DRACONID METEORS 2011

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                                                  Electronic Telegram No. 2862
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
CBAT Director:  Daniel W. E. Green; Hoffman Lab 209; Harvard University;
 20 Oxford St.; Cambridge, MA  02138; U.S.A.
e-mail:  cbatiau en eps.harvard.edu (alternate cbat en iau.org)
URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network


DRACONID METEORS 2011
     P. Jenniskens, SETI Institute, reports that the predicted Draconid
outburst of October 8 (cf. CBET 2819) unfolded much as predicted.  From visual
observations of 2164 Draconids collected by the International Meteor
Organization, G. Barentsen calculated a peak Zenith Hourly Rate (ZHR) of 300
+/- 30 Draconids per hour at Oct. 8d20h03m +/- 10m UT with a shower full-width-
at-half-maximum (FWHM) of 100 minutes.  The shower was rich in faint meteors,
with a population index of chi = 2.80 +/- 0.05.  I. Yrjola (Kuusankoski,
Finland) reports a forward-meteor scatter peak centered at 20h10m UT with FWHM
= 75 min.  The predicted peak time and rate was 20h01m UT and 600/hr,
respectively.
     This outburst resulted from the crossing of the 1900 dust ejecta of comet
21P/Giacobini-Zinner.  Multi-station video observations using the CAMS data
system in northern Germany in support of the Draconid Airborne Observing
Campaign (http://draconids.seti.org; led by J. Vaubaillon, IMCCE; and P. Koten,
Ondrejov Observatory) were reported by Jenniskens together with M. Gerding
(Institute of Atmospheric Physics, Kuehlungsborn) and C. Johannink and M.
Langbroek (Dutch Meteor Society); they note that outburst Draconid meteors
radiated from a geocentric radiant at R.A. = 262.8 +/- 0.7 deg and Decl. =
55.5 +/- 1.1 deg (equinox 2000.0 presumed), with geocentric velocity V_g =
20.9 +/- 1.0 km/s (error margins are 1-sigma dispersions of trajectory
solutions from 28 Draconids, but includes instrument uncertainty).  The
predicted radiant position for the 1900 dust ejecta was at R.A. = 263.2 deg,
Decl. = +55.8 deg, with V_g = 20.9 km/s.  This outburst was detected by
SkyMet radar systems in Andoya (R. Latteck, IAP Kuehlungsborn) and in Canada
(P. Brown, University of Western Ontario).
     The SkyMet meteor radars did not detect the Draconid shower around 17h UT,
when the earth was to cross dust ejected by comet 21P prior to 1900 AD.
However, P. van Leuteren and S. Dijkstra (Dutch Meteor Society, observing from
northern Germany) report 15 relatively bright (magnitude -1 to +2) Draconids
between 17h45m and 18h15m UT, and J. Toth (Modra Observatory, observing from
Kiruna) reports detecting 14 potential bright Draconids with an all-sky camera
while on the tarmac at 16.5-18h UT, according to airborne Campaign participant
J. P. Mc Auliffe of the European Space Agency/ESAC.  Also, a low-background
level of Draconid activity was detected on Oct. 8d10h00m-12h30m UT by K.
Mameta (Kobe, Hyogo-ken, Japan), according to S. Nakano (Sumoto, Japan).

    Kamil Hornoch, Astronomical Institute, Ondrejov, reports results of his
visual observation of Draconids near Barengo, Italy, between Oct. 8.753 and
8.972 UT under clear moonlit skies with an average naked-eye limiting
magnitude of 5.6.  During the interval, 121 Draconids were recorded, including
the brightest one reaching magnitude about -2.5.  He saw a peak ZHR of 550
meteors/hr (using a presumed magnitude-distribution index of 2.6) in an 8-min
interval around Oct. 8.8326 UT.


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

                         (C) Copyright 2011 CBAT
2011 October 16                  (CBET 2862)              Daniel W. E. Green