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(meteorobs) IMO-NEWS: Leonid video outburst over Hawaii, 1997 November
Forwarded without Alastair's permission. If you wish to reply, please
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-Lew Gramer
------- Forwarded Message
Date: Fri, 02 Jul 1999 14:12:59 +0100
From: Alastair McBeath <mcbal.gwyvre@virgindot net>
To: imo-news@imodot net
Subject: Leonid video outburst over Hawaii, 1997 November
Leonid video outburst over Hawaii, 1997 November
From: Alastair McBeath, IMO Vice-President; e-mail:
vice_president@imodot net
Some of you may recall reading about this unusual event in late 1997 or
early 1998. I recently received a copy paper on it from Masao Kinoshita,
one of the observers and authors, and because of its potential
importance particularly to video meteor observers and analysts, those
people involved in Leonid stream modelling, and those who take an
interest in unusual meteoric phenomena, I draw your attention to it
here.
The paper is: "Preliminary activity of Leonid meteor storm observed with
a video camera in 1997", by Masao Kinoshita, Takuya Maruyama & Toru
Sagayama, Geophysical Research Letters volume 26:1, pages 41-44 (1999
January 1). The abstract reads as follows:
"Optical meteor observations were carried out in Mauna Kea, Hawaii, in
November 1997, in order to investigate the activity of Leonid shower
under strong moon shine. We report a spectacular event of a meteor
burst, with 100-150 meteors in only two seconds, observed at the time of
descending node of the comet at 13:31 UT on November 17, 1997. From a
preliminary analysis, the spread of the meteors in the orbit are
estimated to be approximately 100 km along the trajectory and 50 km in
the lateral direction. This observed meteor rate is comparable to the
maximum hourly rate reported in 1966. The video camera observation shown
here can be very useful for observations during the forthcoming strong
Leonid meteor storm."
I must note here that the outburst was observed only by video camera,
however. Photographic cameras active simultaneously recorded only a
couple of meteors, while the visual observer reported seeing just one
meteor (a magnitude -2 event, the brightest detected). This means that a
direct comparison with the visually-estimated ZHRs of the 1966 Leonid
storm cannot be made, as video and visual meteor rates are not the same,
partly because of the video system's more objective viewing techniques,
but also because video cameras are typically far more sensitive to
infra-red radiation than the human eye.
In addition, this video Leonid meteor outburst was not typical of even
previously detected short-lived meteor outbursts from other sources,
such as the Draconids of 1985 or 1998 or the Alpha Monocerotids of 1995,
as it lasted not some minutes or tens of minutes, but 1.57 seconds! It
is more likely that a very small fragment of Comet Tempel-Tuttle which
remained reasonably coherent until quite close to the Earth, or a larger
friable meteoroid in the Leonid stream which broke apart on the outer
fringes of the Earth's atmosphere (as also suggested in the paper by
Kinoshita et al.) was responsible for the small spatial distribution of
the meteoroids in the observed event.
The paper is definitely recommended reading.
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