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(meteorobs) Excerpts from "CCNet 122/2001 - 20 November 2001: LEONIDS FALL WELL BELOW EXPECTATIONS"
------- Forwarded Message
From: Peiser Benny <B.J.Peiser@livjm.acdot uk>
To: cambridge-conference <cambridge-conference@livjm.acdot uk>
Subject: CCNet 122/2001 - 20 November 2001
Date: Tue, 20 Nov 2001 10:56:11 -0000
CCNet 122/2001 - 20 November 2001: LEONIDS FALL WELL BELOW EXPECTATIONS
=======================================================================
"This year's Leonids were marked from excellent lunar conditions.
The weather was also very friendly to most of the observers around the
world. The strongest peak observed is around 18h20min UT which was
suitably situated for the observers in East Asia and Australia. The
rates during this peak reached more then 2800 meteors per hour. This is well
below the theoretically predicted peak levels which were around 5000
according to Lyytinen/Nissinen/van Flaudern or 8000 in Asher/McNaught's
model."
--Vladimir Krumov, International Meteor Organisation, 20 Nov 2001
"There was a very similar event [sonic boom] on Friday 16 November
around 10:15 a.m., according to reports from Peterlee to Gateshead in
north-east England. That source was tracked down quickly, largely
because Police Force HQ at Durham had been shaken by the blast, and
contrary to the RAF's quoted denial re the November 13-14 event, it was
indeed determined to have been a military jet going supersonic a short way
out over the North Sea, where a large flight of aircraft were on
exercises. With military air exercises across northern England/southern
Scotland in recent weeks persisting through till at least 23h UT on
some nights, I would not be surprised to discover the November 13-14 event
was down to a military source, possibly somebody exceeding the sound
barrier when they shouldn't have, hence the RAF's negating comment.
I've had no reports of a bright fireball that night so far certainly,
though skies in NE England were at least partly clear up to midnight then
from my own records."
--Alastair McBeath, Society for Popular Astronomy, 20 Nov 2001
(1) 2001 LEONIDS FALL WELL BELOW EXPECTATIONS
Vladimir Krumov <vkru@yahoo.com>
(2) LEONIDS: WILD STORM OF SHOOTING STARS SEEN SUNDAY MORNING
Space.com, 18 November 2001
[...]
(9) SONIC BOOM OVER SCOTTLAND, NOVEMBER 13-14
Alastair McBeath <vice_president@imodot net>
[...]
===============
(1) 2001 LEONIDS FALL WELL BELOW EXPECTATIONS
>From Vladimir Krumov <vkru@yahoo.com>
- -----------------------------------------------------------
International Meteor Organization
Meteor Shower Circular
2 0 0 1 L E O N I D S
- -----------------------------------------------------------
This year's Leonids were marked from excellent lunar conditions. The weather
was also very friendly to most of the observers around the world.
The strongest peak observed is around 18h20min UT which was suitably
situated for the observers in East Asia and Australia. The rates during this
peak reached more then 2800 meteors per hour. This is well below the
theoretically predicted peak levels which were around 5000 according to
Lyytinen/Nissinen/van Flaudern or 8000 in Asher/McNaught's model.
As far as the first peak, observed from America, is concerned rates were
between 1000 and 1500 meteors per hour. However there is still not enough
data reported from it especially about the time after 11 UT.
The first activity profile is derived from the observations of 38 observers.
It is aimed to give a general view of the observed shower and no conclusions
can be made on this stage. The following detail analysis will tell us more
about the shower and the dust trail models.
Data of the following observers is included in the preliminary profile. The
countries in brackets show the place where observations were carried out,
not necessarily his home land :
Albert Kong (USA), Andreas Buchman (Germany), Andrzej Skoczewski (Poland),
Antonio Martinez (Venezuela), Brian Shulist (Canada), Camila Bacher (USA),
Carles Pineda Ferre (Spain), Detlef Koschny(Australia), Francisco A.
Rodriguez Ramirez (Spain), Gaurav Rathod (India), Ina Rendtel (Germany),
James Bedient (USA), Jaydeep Belapure (India), Joe Zemder (Australia), Josep
M. Trigo-Rodriguez (Spain), Joseph Zammit (Malta), Kamil Hornoch (Pland),
Ken Hodonsky (USA), Kim Youmans (USA), Marion Rudolph (Germany),Mark Davis
(USA), Martin Galea De Giovanni (Malta), Mayuresh Girish Prabhune (India),
Michael Doyle (USA), Miguel A. Serra (Spain), Mike Linnolt (USA), Rafael
Haag (Brazil), Rainer Arlt (Korea), Robert Lunsford (USA), Shigeo Uchiyama
Japan), Sirko Molau (Korea), Tom Roelandts (China), Tomislav Jurkic
(Croatia), Umberto Mul? Stagno (Tunis), Valentin Velkov (Bulgaria), Werner
Hamelinck (China), Xiaorong Wang (China), Zhou Xingming (China)
_____________________________________
Date Time Sollong Nint Nobs ZHR +/-
- --------------------------------------
18 0100 235.732 23 8 52 4
18 0300 235.816 22 9 80 3
18 0500 235.900 21 8 95 5
18 0630 235.963 11 5 160 10
18 0730 236.005 15 7 200 10
18 0815 236.036 13 5 150 10
18 0845 236.057 15 5 270 15
18 0915 236.078 18 6 430 20
18 0945 236.099 12 6 570 20
18 1015 236.121 17 6 790 25
18 1045 236.142 20 5 1000 25
18 1130 236.173 8 2 400 40
18 1300 236.236 12 2 370 25
18 1430 236.299 9 1 320 20
18 1530 236.341 16 3 490 30
18 1630 236.383 16 3 780 40
18 1700 236.404 16 4 1100 50
18 1730 236.425 18 4 1550 50
18 1800 236.446 20 5 2320 60
18 1820 236.460 28 7 2850 60
18 1840 236.474 32 7 2430 50
18 1900 236.488 21 6 1580 50
18 1920 236.509 18 5 1160 40
18 1940 236.516 17 5 1020 40
18 2000 236.530 17 7 800 30
18 2030 236.551 13 5 470 20
18 2120 236.587 16 5 150 10
18 2220 236.629 7 4 130 10
______________________________________
Calculations are made for population index r=2.0. Nint is the number of
intervals observing intervals in a certain period. Nobs is the number of
different observers in it.
Many thanks to all the observers that have contributed their data. Also to
the favorable weather conditions whish are not so typical for this part of
the year.
Clear Skies,
Vladimir Krumov
==============
(2) LEONIDS: WILD STORM OF SHOOTING STARS SEEN SUNDAY MORNING
>From Space.com, 18 November 2001
http://www.space.com/scienceastronomy/astronomy/leonids_wrap_011118.html
By Robert Roy Britt
Senior Science Writer
Vivid streaks of light, sometimes several at a time, zipped across the early
Sunday morning sky as the 2001 Leonid meteor shower reached a stunning
crescendo. A few of the meteors exploded into dazzling fireballs as
skywatchers in North America and elsewhere witnessed ancient space dust
plunging into Earth's atmosphere and vaporizing.
The event was well documented by scientists, and it will live forever in the
memories of thousands of amateur astronomers and first-time viewers who
braved sometimes chilly weather and fought off sleep.
"It was a fabulous show," said Jim Graham of New York City, who traveled
about 100 miles north to view the Leonids under darker skies. "At one point
we saw six at once, in about a second. Some seemed to have a punctuation
mark at the end, with a little trail that blows up. We saw one that lit up a
big piece of the sky and just exploded at the end."
"It was unbelievable," said Robin Lloyd, who works at the American Museum of
Natural History in New York and watched with Graham and his son. "It was the
most beautiful thing."
It's too soon to say for sure whether the 2001 Leonid meteor shower, which
peaked before dawn, will qualify as a storm as scientists had predicted. But
early indications point to a storm designation. A meteor storm is defined as
a shower that exceeds an hourly rate of 1,000 meteors.
Either way, it was unlike anything seen on Earth since 1966, professionals
and casual observers agreed. And astronomers say it won't be repeated for
nearly a century.
Reports from many locations
Early risers from California to Ohio to Virginia and elsewhere described
similar experiences -- an occasionally wild show with peaks and lull, all
lasting from shortly after midnight until dawn.
Some witnesses described fast-moving meteors, zooming across all parts of
the sky and sometimes leaving smoky trails.
In rural Maryland under fairly dark skies, this reporter counted four
meteors per minute during a five-minute stretch at 4 a.m., but by 5 a.m.
that count grew to more than eight per minute. That equates to an hourly
rate of 480. But many meteors went unseen on a foggy horizon.
A group of scientists reported an hourly rate of 800 shooting stars above
New Mexico. A Texas observer counted dozens in a few seconds -- and did so
several times. Other groups observing in the Southwest reported preliminary
estimates in the neighborhood of 2,000 meteors per hour for a short stretch
of time.
A stronger display was expected in Australia and parts of eastern Asia. One
preliminary report from a group of NASA scientists claimed an hourly rate of
1,250 meteors in Hawaii. One early and rough report from China indicates
rates may have reached 2,000 or more.
Behind the show
The display was the result of space dust vaporizing in Earth's atmosphere.
Most of the shooting stars were created by stuff no larger than sand grains.
The debris is the exhaust of comet Tempel-Tuttle, which orbits the Sun every
33 years. Earth passed through several separate trails of this debris over
the weekend. Some of the trails had been laid down centuries ago.
Four different research groups had predicted when and where various peaks of
activity would occur, and how many meteors per hour would be visible at the
peak time. But meteor shower forecasting is in its infancy. Serious Leonids
forecasts go back to just 1998.
The predictions for North American ranged from 800 meteors per hour to
4,200. In parts of Asia and Australia, a peak hourly rate of 8,000 or more
was expected. The hourly rates were expected to be achieved during short
bursts that would last 30 minutes or less.
The show is not entirely over. Though the peak is past, the Leonids will
wind down through Nov. 21. Each morning until then offers an opportunity to
see some shooting stars, both those associated with the Leonids as well as
others.
This time of year is a busy one for shooting stars in general.
Monday morning observers with dark skies can expect to see up to 35 total
meteors per hour in the Northern Hemisphere and 20 in the Southern
Hemisphere, according to Robert Lunsford of the American Meteor Society.
Unpredictable bursts of Leonid activity could send the rates higher for
short stretches. Similar activity was spotted early Friday and Saturday.
While the Leonids are also visible in Europe and elsewhere, the strong
bursts of activity were confined to a few regions of the globe.
Next year's Leonids are expected to equal or exceed this year's count, but
the show will be largely drowned out by a full Moon.
Satellite threat
Satellite operators have been watching the Leonids with wary eyes. A
fast-moving Leonid meteor can damage or disable a satellite. NASA scientist
and meteor forecaster Bill Cooke said before the shower that there would be
between 1-in-10,000 and 1-in-1,000 chance of at least one satellite being
significantly damaged during the full duration of the shower.
So far, there have been no reports of satellite damage.
Defense officials have said military satellites are more robust than most
and are capable of withstanding an impact. Measures were taken to protect
spy satellites and other spacecraft critical to military operations, but
officials would not say what those precautions were.
Copyright 2001, Space.com
============================
* LETTERS TO THE MODERATOR *
============================
(9) SONIC BOOM OVER SCOTTLAND, NOVEMBER 13-14
>From Alastair McBeath <vice_president@imodot net>
Dear Benny,
I've just scanned the press reports on this sonic boom in CCNet 120/2001.
There was a very similar event on Friday 16 November around 10:15 a.m.,
according to reports from Peterlee to Gateshead in north-east England. That
source was tracked down quickly, largely because Police Force HQ at Durham
had been shaken by the blast, and contrary to the RAF's quoted denial re the
November 13-14 event, it was indeed determined to have been a military jet
going supersonic a short way out over the North Sea, where a large flight of
aircraft were on exercises. With military air exercises across northern
England/southern Scotland in recent weeks persisting through till at least
23h UT on some nights, I would not be surprised to discover the November
13-14 event was down to a military source, possibly somebody exceeding the
sound barrier when they shouldn't have, hence the RAF's negating comment.
I've had no reports of a bright fireball that night so far certainly, though
skies in NE England were at least partly clear up to midnight then from my
own records.
Best wishes,
Alastair McBeath,
Society for Popular Astronomy: Meteor Director
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