Hi,

After Yesterday's thunderstorm , the night sky miraculously cleared out and
crispy clear skies were enjoyed by the lucky observers at Ras Il Qammieh .
Unfortunately high humidity and a thin layer of haze made observations for
some hours impossible.

We managed to observe Linearids (possible ? ), N Taurids , S Taurids and
Leonids.

Observation report for 13 - 14 / 11 / 1999
Location : Ras Il Qammieh Malta Europe (Lat 35.59 N  Long 14.19 E )
Observers :
		 Martin Galea De Giovanni (GALMA)
		 Alexei Pace (PACAL)
		 Joseph Zammit (ZAMJO)

Please note that the Times are all in UT and of the night 13-14/ 11 / 1999


Observation Of GALMA (1)

Start time 00:20
End Time 01:21
Total Observing time = 61 minutes
Effective Time = 58 minutes
Obscuration 30 % for 10 minutes

SLM @ 00:20 (UT) = + 6.0
SLM @ 1:21 (UT) =   + 5.4

Totals
Total number of meteors = 11
Sporadic = 2
Leonids = 3
N Taurids = 6

Magnitude distribution

Sporadic

Magnitude 	 number of meteors
2 	 1
3 	 1


Leonids

Magnitude 	 number of meteors
1 		 1
2 	 1
4 	 1


Taurids N

Magnitude 	 number of meteors
-2 		 1
0 	 2
1 		 1
3 		 2


----------------------------------------------------------------------------
--------------
Observation Of GALMA (2)

Start time 03:00
End Time 04:00
Total Observing time = 60 minutes
Effective Time = 57 minutes
Obscuration 10 % for 10 minutes

SLM @ 03:25 (UT) = + 5.7

Totals
Total number of meteors = 18
Sporadic = 6
Leonids = 8
N Taurids = 2
Possible Linearids = 2

Magnitude distribution

Sporadic

Magnitude 	 number of meteors
1 	 2
3 	 2
4 	 1
5 	 1


Leonids

Magnitude 	 number of meteors
0 		 2
1 	 2
2 	 2
3 	 1
5 	 1


Taurids N

Magnitude 	 number of meteors
3 		 1
4 		 1

Possible Linearids

Magnitude 	 number of meteors
0 		 1
1 		 1

----------------------------------------------------------------------------
--------------
Observations for PACAL

Start time 00:30
End Time 01:30
Total Observing time = 60 minutes
Effective Time = 59 minutes

SLM  = + 6.2


Totals
Total number of meteors = 9
Sporadic = 2
N Taurids = 7

Magnitude distribution

Sporadic

Magnitude 	 number of meteors
2 	 1
4 	 1



Taurids N

Magnitude 	 number of meteors
0 		 1
1 		 3
2 		 2
3 		 1


----------------------------------------------------------------------------
--------------

Observations for ZAMJO

Start time 23:19
End Time 00:48
Total Observing time = 89 minutes
Effective Time = 68 minutes

SLM @ 23:19 (UT) = + 5.1
SLM @ 00:48 (UT) =   + 5.7

Totals
Total number of meteors = 23
Sporadic = 8
Linearids = 1
Leonids = 1
N Taurids = 13

Magnitude distribution

Sporadic

Magnitude 	 number of meteors
1 	 1
2 	 2
3 	 2
4 	 3


Leonids

Magnitude 	 number of meteors
1 		 1


Linearids (possible)

Magnitude 	 number of meteors
+4 		 1


Taurids N

Magnitude 	 number of meteors
-1 		 1
0 		 1
1 		 1
2 		 2
3 		 5
4 	 3

----------------------------------------------------------------------------
--------------


Clear Skies
Martin Galea De Giovanni



Visit the NEW page of the Astronomical Society Of Malta at
www.geocities.com/maltastro

HRO Today, Japan   Nov.16, 1999
///////////////////////////////////////////////////////
HRO (Forward-scattered Radio Meteor Observation using HAM) Data from Japan
by Kazuhiro Suzuki,  E-mail: kazuhiro@...
URL: http://www.tcp-ip.or.jp/~kaze/rmd.htm    "Radio Meteor Data, JAPAN"
///////////////////////////////////////////////////////
Observer:      Kazuhiro Suzuki
Location:      Toyokawa Meteor Observatory (137.32 deg E, 34.81 deg N)
Toyokawa-city, Aichi, 442-0845, JAPAN
Transmitter:   JA9YDB 53.7500 MHz, CW 50 W operated by Mr. Kimio Maegawa(Fukui
National College of Technology)
Receiver:      IC-575 (ICOM)  LSB  BW 2.5 kHz
Antenna:       Dipole (height 7 m, to zenith)
Transmitter location: Sabae (in Fukui pref.), about 150 km north north-west from
receiving station.
Method of echo sampling: After image procedure by PC with FFT software,
echoes(>10 dB(S/N)) were counted.

LT   00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23
UT   15 16 17 18 19 20 21 22 23 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14
---------------------------------------------------------------------
November,1999    (LT=UT+9h)
13/  18 35 36 37 26 23 22 32 29 29 32 25 Es Es@19 17 22 17 16 19 26@21 26@23
          1        1  1        1  1
14/  25 39 45 31 31 31 38 28 40@29 IF 26 25 IF IF 14 17 IF IF IF IF@25 24@27
             1  1     1           1
15/  30 32 38 40 49 32@38 35 38@34@24 32 30 28 28 21 17 16 17 19 23 21 15@14
       1     1              1           1
16/  27 33 36 35 34 31 29 IF IF@27 33 28 26 27@18 IF IF IF IF IF
                                 @3  3
------------------------------------------------------------------
@symbol means corrected hourly rate.  Es symbol means interruption by
Sporadic E layer.  IF symbol means interference by foreign broadcasting.
  up/middle/down : hourly rate of all echoes / hourly rate of long(> 20 sec.)
echoes/dead time rate(%) caused by persistent echoes

I began my 1999 Leonids campaign with a peaceful, lovely 3.9 hour
Teff observing session last night. Highlight of the night was my
first Leonid of the historic 1999 Leonids, at 6:15UT. A tiny mag
5 ziffer, but I was thrilled nonetheless. :)

Long Key State Park continues to be a dark, serene, natural place
to observe from, though I noted with alarm on the trip down that a
rapid growth of new high-end tourist hotels has sprung up just in
the last year... Perhaps very soon LKSP may cease to be dark? :(

The Florida Video Team of this year's NASA/Marshall Space FLight
Center Leonids Campaign seems to have all equipment well in hand,
and I believe they will be ready to begin data gathering tonight.


Here's my summary for the night: I'll try to make similar reports
as the week progresses, though between observing, transcribing and
sleep (in that order of importance), my time may get limited!

14/15 Nov 1999, Lew Gramer GRALE, Location: 24:49:01 N, 80:49:12 W
Per Start End  CFV    Teff LM   F    LEO  AMO  NTA  STA  Tau  Spor TOTAL
1   3:30  4:50 04h+15 1.01 7.46 1.00 0    0    3    1    2    14   20
2   4:51  6:05 04h+15 1.02 7.43 1.00 0    3    2    4    2    12   23
3   6:06  7:15 05h+15 1.02 7.46 1.00 2    2    4    3    2    19   32
4   7:16  8:10 05h+15 0.84 7.50 1.00 6    2    0    1    4    9    22
TOTALS                3.88 7.46 1.00 8    7    9    9    10   56   99
Average Magnitudes                   4.19 4.79 3.17 3.44 4.10 4.15 4.04


Take care all, and clear skies from the Florida Keys!
Lew Gramer

From the Canary Island of La Palma observers from the Dutch NVWS Meteor
Section do obtain visual observations as well as photographic and video
since November 11. Information about the visual results can be found at
www.astro.uu.nl/~bettonvl.

Best Regards,

Felix Bettonvil

HRO Today, Japan   Nov.15, 1999
///////////////////////////////////////////////////////
HRO (Forward-scattered Radio Meteor Observation using HAM) Data from Japan
by Kazuhiro Suzuki,  E-mail: kazuhiro@...
URL: http://www.tcp-ip.or.jp/~kaze/rmd.htm    "Radio Meteor Data, JAPAN"
///////////////////////////////////////////////////////
Observer:      Kazuhiro Suzuki
Location:      Toyokawa Meteor Observatory (137.32 deg E, 34.81 deg N)
Toyokawa-city, Aichi, 442-0845, JAPAN
Transmitter:   JA9YDB 53.7500 MHz, CW 50 W operated by Mr. Kimio Maegawa(Fukui
National College of Technology)
Receiver:      IC-575 (ICOM)  LSB  BW 2.5 kHz
Antenna:       Dipole (height 7 m, to zenith)
Transmitter location: Sabae (in Fukui pref.), about 150 km north north-west from
receiving station.
Method of echo sampling: After image procedure by PC with FFT software,
echoes(>10 dB(S/N)) were counted.

LT   00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23
UT   15 16 17 18 19 20 21 22 23 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14
---------------------------------------------------------------------
November,1999
11/  17 37 48 41 39 35 46 30 47 46 41 29@18 IF IF IF IF IF IF IF@19 IF IF@15
                1        2  1
12/  20 39 31 35 36 34 31 34 27 23 28 28 30 23 20 IF@15@16 IF IF@14 IF@18@17
                      1              1  1        1
13/  18 35 36 37 26 23 22 32 29 29 32 25 Es Es@19 17 22 17 16 19 26@21 26@23
          1        1  1        1  1
14/  25 39 45 31 31 31 38 28 40@29 IF 26 25 IF IF 14 17 IF IF IF IF@25 24@27
             1  1     1           1
15/  30 32 38 40 49 32@38 35 38@34@24 32 30 28 28 21 17 16
       1     1              1           1
------------------------------------------------------------------
@symbol means corrected hourly rate.  Es symbol means interruption by
Sporadic E layer.  IF symbol means interference by foreign broadcasting.
  up/middle/down : hourly rate of all echoes / hourly rate of long(> 20 sec.)
echoes/dead time rate(%) caused by persistent echoes

HRO Today, Japan   Nov.14, 1999
///////////////////////////////////////////////////////
HRO (Forward-scattered Radio Meteor Observation using HAM) Data from Japan
by Kazuhiro Suzuki,  E-mail: kazuhiro@...
URL: http://www.tcp-ip.or.jp/~kaze/rmd.htm    "Radio Meteor Data, JAPAN"
///////////////////////////////////////////////////////
Observer:      Kazuhiro Suzuki
Location:      Toyokawa Meteor Observatory (137.32 deg E, 34.81 deg N)
Toyokawa-city, Aichi, 442-0845, JAPAN
Transmitter:   JA9YDB 53.7500 MHz, CW 50 W operated by Mr. Kimio Maegawa(Fukui
National College of Technology)
Receiver:      IC-575 (ICOM)  LSB  BW 2.5 kHz
Antenna:       Dipole (height 7 m, to zenith)
Transmitter location: Sabae (in Fukui pref.), about 150 km north north-west from
receiving station.
Method of echo sampling: After image procedure by PC with FFT software,
echoes(>10 dB(S/N)) were counted.

LT   00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23
UT   15 16 17 18 19 20 21 22 23 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14
---------------------------------------------------------------------
November,1999
  9/  20 35 33 39 34 30 28@27@33 30 26 29 32 21 17 21 18 20@14 18 21 31 22@19
          1  1     2     2              1
10/  25 32 42 33 35 30 41 34 40 26 33 29 31 36 Es@18 21 17 15 21@18 25 26@23
          1                 1  2  1                             1
11/  17 37 48 41 39 35 46 30 47 46 41 29@18 IF IF IF IF IF IF IF@19 IF IF@15
                1        2  1
12/  20 39 31 35 36 34 31 34 27 23 28 28 30 23 20 IF@15@16 IF IF@14 IF@18@17
                      1              1  1        1
13/  18 35 36 37 26 23 22 32 29 29 32 25 Es Es@19 17 22 17 16 19 26@21 26@23
          1        1  1        1  1
14/  25 39 45 31 31 31 38 28 40@29 IF 26 25
             1  1     1           1
------------------------------------------------------------------
@symbol means corrected hourly rate.  Es symbol means interruption by
Sporadic E layer.  IF symbol means interference by foreign broadcasting.
  up/middle/down : hourly rate of all echoes / hourly rate of long(> 20 sec.)
echoes/dead time rate(%) caused by persistent echoes

Hello colleagues,

Throughout the upcoming week, the American Meteor Society (AMS) will be
maintaining a Leonids '99 Update page at the AMS web site, located at:

http://www.amsmeteors.org/leo99update.html

The purpose of this page is to provide a narrative description, along with
eyewitness accounts, of the 1999 Leonid meteor shower as compiled from
reports received by the AMS and our affiliate group, the North American
Meteor Network (NAMN).  We are designing this page to act as a compliment
to the reporting efforts and analysis of the International Meteor
Organization (IMO), Dutch Meteor Society (DMS), and other related groups.
Although observed hourly rates and shower characteristics will be given, we
do not intend to offer a detailed analysis or ZHR profile (leaving this to
the other groups).  Instead, we intend to compile a historical record of
selected anecdotal accounts and personal impressions of the 1999 Leonids.

Many of the accounts included on this page will undoubtedly come from the
MeteorObs mailing list, but we would *greatly* appreciate receiving reports
from all of the various professional and amateur Leonid expeditions
worldwide.  If you would like to send us a narrative account of your
personal Leonid experience, in addition to the scientific data collection
which you are doing, I can receive your reports at the below email address:

Jim Richardson <richardson@...>

Selected narratives will be posted on the AMS web site as quickly as
possible, in addition to commentary on the overall shower activity, with a
final edited collection of Leonid accounts to appear in the next issue of
the AMS journal, Meteor Trails.  This was done with good success last year,
and it is hoped that these historical narratives will prove to be a
enjoyable companion to the numerous scientific studies being performed.

Best regards,

      Jim


James Richardson
Department of Physics
Florida State University (FSU)

Operations Manager
American Meteor Society (AMS)
http://www.amsmeteors.org

-------------------------------------
             I M O   S h o w e r   C i r c u l a r
             -------------------------------------

         Possible Activity from Comet C/1999 J3 LINEAR


A slight chance of meteor shower activity caused by debris from Comet
C/1999 J3 (LINEAR) encouraged quite a few observers to check for
meteors from a radiant position near alpha=175deg, delta=+53deg as
predicted from the orbit of the Comet.

No activity outburst occurred. The below list of individual ZHR
values indicates weak activity all day on November 9, 1999, and
in the evening hours of November 11 near the passage of the node
of the comet's orbit. On several occasions the radiant elevation
was too low for a sensible ZHR value. Due to possible contamination
by sporadic background activity, the activity cannot be reliably
associated with particles from the Comet.

Radar records from Ondrejov, Czech Republic, indicate enhanced
activity between 21h and at least 3h UT on November 11/12 comared
with the day before (see http://sunkl.asu.cas.cz/~stork/linearids.html).
The activity is associated with faint meteors, possibly beyond the
visual range. No clear enhancement appears in the forward scatter data
by Kazuhiro Sizuki (see http://www.tcp-ip.or.jp/~kaze/data/htyk9911.htm).

-------------------------------------------------------------------------
Date    Period UT   LM LIN nonLIN hR ZHR  Observer
-------------------------------------------------------------------------
Nov 08  1335-1415  6.0   2    3    4   -  Qi Rui (China)
Nov 08  1441-1528  6.0   0    6        0  Qi Rui (China)
Nov 08  1620-1750  6.0   3   15   18   9  Qi Rui (China)
Nov 08  1830-2027  6.0   0   14        0  Qi Rui (China)
Nov 09  0330-0430  5.1   0    3        0  Peter Detterline (USA)
Nov 09  0746-0846  5.6   1    8   38   3  Peter Detterline (USA)
Nov 09  0846-0946  5.4   1    7   48   5  Peter Detterline (USA)
Nov 09  2220-2321  5.8   2   10   22   9  Alastair McBeath (UK)
Nov 09  2322-0022  5.8   2   10   26   8  Alastair McBeath (UK)
Nov 10  0022-0122  5.8   2   12   31   7  Alastair McBeath (UK)
Nov 10  0123-0228  5.8   0   18        0  Alastair McBeath (UK)
Nov 10  0655-0755  5.1   0    8        0  Mark Davis (USA)
Nov 10  0755-0855  5.2   0    8   32   0  Mark Davis (USA)
Nov 10  0855-0955  5.3   0    8        0  Mark Davis (USA)
Nov 10  1830-1900  4.0   0    3   17   0  C.L. Chan (Hong Kong)
Nov 10  2200-0000  6.0  (3)   8        -  Ulhas Deshpande et al. (India)
Nov 11  0001-0107  5.7   0   12   21   0  Joseph Zammit (Malta)
Nov 10  2323-0423  5.9   7   55   32   4  Martin Galea (Malta)
Nov 11  0257-0424  6.0   2   17   48   3  Joseph Zammit (Malta)
Nov 11  0356-0508  6.0   0    7   44   0  Alfredo Pereira (Portugal)
Nov 11  0330-0715  5.8   1    9   ~0   -  Mike Linnolt (USA)
Nov 11  0701-0801  5.3   0    7        0  Mark Davis (USA)
Nov 11  0801-0921  5.4   0   10        0  Mark Davis (USA)
Nov 11  1845-1913  5.8   0    2        0  Qi Rui (China)
Nov 11  1900-2000   -    0   19        0  Peter Zimnikoval et al. (Slovakia)
Nov 11  1910-2015  6.1   1    7   15   5  Jurgen Rendtel (Germany)
Nov 11  1913-2014  5.8   1   12   40   3  Qi Rui (China)
Nov 11  1900-2100  4.8   0    5    2   -  J. Marques, R. Afonso (Portugal)
Nov 11  1900-2115  5.9   0   14   15   0  Frank Enzlein (Germany)
Nov 11  1900-2130  5.8   0   15   15   0  Nikolai Wuensche (Germany)
Nov 11  2115-2130  5.8   1    5   55  10  Qi Rui (China)
Nov 11  2200-2300  6.0  (5)   8        -  Ulhas Deshpande et al. (India)
Nov 12  0022-0320  6.0   2   33   32   2  Umberto Mule Stagno (Malta)
Nov 12  0020-0324  5.8   2   41   33   2  Joseph Zammit (Malta)
Nov 12  0020-0340  5.9   3   39   34   3  Martin Galea (Malta)
-------------------------------------------------------------------------

I would like to thank all the above observers for their efforts
and swift reports, and I hope I did not overlook any message in
this busy time before the Leonids.

Rainer Arlt, 1999 November 13
-----------------------------

NOTE: The WWW server of the IMO is down, probably until Monday, for
unknown reasons. Its site is alarm secured and cannot be accessed
before Monday. Please apologize for the inconvenience.

IMO-news messages should be directly sent to the distributing
server at: imo-news@eGroups.com

1999 November 11, Period: 1900-2100 UT
Sky clear but with light pollution
Field centre: Polaris
Average Lm by star counts using IMO areas 7 and 14, yields Lm= 4.8

NO meteor was seen that could be considered a Linearid candidate.

Observed meteors:

1908    Tau    -1
2001    Tau      0
2022    Tau      0
2048    Tau      2
2056    Tau      2
Total: 5 meteors

Observers: José Marques and Ricardo Afonso (beginners observers)

Location: Belas, Portugal (38.7670N, 9.2670W)

Ricardo Afonso

Dear meteor observers,

I observed visually on Nov 11, between 19:10 and 20:15 UT. Among
the 8 meteors is 1 candidate for the "Linearids". Furthermore,
my automated video camera worked all night (16:45 UT - 05:00 UT),
but I have not yet checked the data. However, the number of
total meteors was not unusual. (Location: 52.5 deg N, 12.9 deg E,
expected radiant above the horizon all time)

Juergen Rendtel


--
************************************************************************
Juergen Rendtel                          Astrophysical Institute Potsdam
jrendtel@...                                      Telegrafenberg A 27
Phone: (+49) 331 - 288 2327 (office)              14473 Potsdam, Germany
Fax:   (+49) 331 - 288 2310
http://aipsoe.aip.de/~rend/rnl-p.html

				        International Meteor Organization
Phone: (+49) 33208 - 50753  (priv.)   Seestr.6, 14476 Marquardt, Germany
************************************************************************

--
Whilst sending my visual results I saw the mail with Ondrejov radar
results, and I still had time for a short additional watch using
14x100B's.  I had to spend time dark adapting again, and dawn was
approaching, so I could not achieve a longer watch period, still my
negative result shows that any substantial Linearid activity at this
moment must be of very faint telescopic meteors (below visual mag +9).

14x100 binoculars; field 3.5 degrees
Limiting magnitude about 12.1-12.5
Field: R.A.=13h 20m  Dec.=+86d 30' (J2000.0)
Interval: 0518-0603 UT.  Effective time: 30 minutes
Observed meteors: 1 probable TAU (mag 7) and 1 SPO (mag 9.5)

Observer PERAF = Alfredo Pereira
Cabo da Roca, Portugal (Lat. 38d 46' 52.1" N  Lon. 9d 28' 33.4" W  Alt. 235m)

Cheers,

Alfredo Pereira
apereira@...
http://correio.cc.fc.ul.pt/~apereira  [Comet Observers' Forum]
--

--
Further results of watch for meteors associated with C/1999 J3 (LINEAR):

1999 November 11-12, Period: 0225-0325 UT.  Effective watch time: 1h 00m
Sky clear.  F=1.0   Field centre: Azimuth 350 deg.  Altitude 75 deg.
Average Lm by star counts using IMO areas 17 and 20, yields Lm=6.05

NO meteor was seen that could be considered a Linearid candidate.

Magnitude distribution of observed meteors:

Mag.   0  +1  +2  +3  +4  +5   total
====================================
TAU    1   0   2   1   3   1     8
SPO    1   0   1   1   3   2     8
------------------------------------
total  2   0   3   2   6   3    16

Observer PERAF = Alfredo Pereira
Cabo da Roca, Portugal (Lat. 38d 46' 52.1" N  Lon. 9d 28' 33.4" W  Alt. 235m)

Cheers,

Alfredo Pereira
apereira@...
http://correio.cc.fc.ul.pt/~apereira  [Comet Observers' Forum]
--

Dear colleagues,
on http://sunkl.asu.cas.cz/~stork/linearids.html you can find first results
from Linearids observations by Ondrejov backscatter radar. Small activity
of faint, short meteors detected.

Petr Pridal
Rosta Stork

Hi all,

The Dutch Meteor Society is proud to announce to have setup a mirrorsite
for all US visitors of our DMS-website.

http://members.xoom.com/dmswebsite/index.html

We expect heavy traffic to our main DMS website which is why we ask our
visitors in the US to use the above URL rather then the main one located in
the Netherlands. You will enjoy faster access and there will be less chance
the website going down because of overloading.

Of course we will do our utmost best to maintain all three DMS-websites
simultaniously during the upcoming Leonids.

As most of you know in the next two weeks we will be on the way somewhere
in Europa in our never ending search for a clear view on the nightsky and
thus to the Leonids. All our DMS-teams are equipped with state-of-the-art
communication technology consisting of mobile power generators, laptops and
GSM mobile phones.
Don't be afraid: anytime and everywhere we will have the opportunity to
supply you with the lastest information concerning our observations of the
Leonids.

So please stay tuned with the Leonids '99 Expedition of the observing teams
of the Dutch Meteor Society. Thank you!

Main URL:  http://www.dmsweb.org

US mirror:  http://members.xoom.com/dmswebsite/index.html

Europe mirror: http://home.wanadoo.nl/dms/index.html

All members of Dutch Meteor Society whishes everybody fine observations and
lots of Leonids!

Casper.



Casper ter Kuile, Dutch Meteor Society (DMS)
Akker 145, NL-3732 XD, De Bilt, The Netherlands
Tel. +(31)-30-2203170, Fax. +(31)-30-2202695
GSM-BEN: +(31)-6-24242445, GSM-KPN: +(31)-6-53270844
E-mail_1: pegasoft@...
E-mail_2: dms-web@...
E-mail_3: webmaster@...
DMS website: http://www.dmsweb.org
Mirrorsite: http://home.wanadoo.nl/dms

I N T E R N A T I O N A L   M E T E O R   O R G A N I Z A T I O N

1999 Leonids: Rapid Information Dissemination
=============================================

Dear meteor observer,

From earlier communications, you have learned that the IMO is setting
up a communication network to obtain reliable information as soon as
possible after the event in the morning of November 18. We invite you
to contribute to this effort.

First of all, we want to point out you must DISTINGUISH between the
USUAL OBSERVATIONAL REPORTS, such as collected by the IMO's Visual
Commission, and which may be used for detailed, global analyses, and
the "EXPRESS REPORT" described below which serves as sole purpose the
compilation of a rough but reliable picture of the activity within
hours after the event.

The EXPRESS REPORT should have the following format:

Meteo R. Observer
Fireball City (45N 10E)

Time Interval (UT)    Lim. Magn.    Nr. of Leonids     Remarks (if any)
-----------------------------------------------------------------------
01:15-01:30           5.8           27                 None
01:30-01:45           5.9           56                 None
01:45-02:00           6.1           156                None
     .
     .
     .

To the extent possible, bin your observations for this "express report"
in time interval of 15 MINUTES.

(Again, the full report of your observations will be different from
this express report, as shorter intervals are required as well as
magnitude distributions and some additional data - see the earlier
posted article with visual observing hints - but the above data
suffice for the purpose indicated.)

If you wish to collaborate with the IMO in this respect, please send
your express report for the night of November 17/18 ONLY (or, of course,
for any unexpected activity you might happen to witness)
*** IMMEDIATELY AFTER THE OBSERVATION *** to the following email
addresses:

wgn@...
gyssens@...

The latter is a back-up address in case Web-site access to www.imo.net
would prove to slow down our computer too much. This back-up address
will be active only on November 17 and 18!

Thank you in advance for any collaboration we may receive!

Marc Gyssens
International Meteor Organization

--
Results of watch for meteors associated with C/1999 J3 (LINEAR):

1999 November 10-11, Period: 0356-0508 UT
Effective watch time: 1h 01m.  Sky clear.  F=1.0
Field centre: Azimuth 350 deg.  Altitude 75 deg.
Average Lm by star counts on three occasions during the watch,
using IMO areas 17 and 20, yields Lm=6.04

NO meteor was seen that could be considered a Linearid candidate.

Magnitude distribution of observed meteors:

Mag.  +1  +2  +3  +4  +5   total
================================
TAU    1   0   1   0   2      4
SPO    0   0   1   0   2      3
--------------------------------
total  1   0   2   0   4      7

Observer PERAF = Alfredo Pereira
Cabo da Roca, Portugal (Lat. 38d 46' 52.1" N  Lon. 9d 28' 33.4" W  Alt. 235m)

Cheers,

Alfredo Pereira
apereira@...
http://correio.cc.fc.ul.pt/~apereira  [Comet Observers' Forum]
--

Hello Craig,

>  Questions :  Which  lens would best for the showers?
> How large a field is optimal?

that depends mainly what you intend to do with your video observations.
Wide angle systems give usually the most 'impressive' video recordings
since you record on average brighter meteors. However, the spatial
resolution is not as good as for a normal or tele system. So, if you want
to obtain the radiant position or do double station observations, a
smaller field of view is preferable.
In this year we expect much more fainter meteors than in 1998, which is
another reason to give priority to a good limiting magnitude. This is why
I would suggest to use a normal or moderate tele lens, for example a fast
50 mm lens.
A field of view of 20 deg with limiting magnitudes of 8 to 9 mag for stars
should be ok.

> Where is the best place to aim the system?

You should neither look directly at the radiant (pointlike meteors are
hard to detect) nor too far away from it (long & fast meteor trails). A
fov some 30..40 deg west of the radiant is probably a good choice.

> It can and will be mounted on a driven scope.

For three reasons I will not do so with my own camera:
* the mounting need to be accurately aligned with the pole to prevent
drifting stars, which my meteor detection software would have
difficulties to cope with
* not to drive your camera means that you always look at the same volume
atmosphere under identical conditions (extinction, etc), which should make
it easier to derive flux rates from the counts
* you do automatically observe meteors in different positions around the
radiant, which gives a better radiant plot from single station data

Best regards,
Sirko Molau

----------------------------------------
Sirko Molau -- Video Commission Director
International Meteor Organization
e-mail: video@...
WWW   : http://www.imo.net/video
----------------------------------------

Dear members of the IMO,

The Aerospace Corporation is providing a website devoted to Leonid meteor
reporting during next week's event (www.leonidstorm.com). Our site will
display plots of activity for the various contributors from around the globe.
We currently have amateurs from the Middle East, UK, Europe, and the US, and
professionals from The Aerospace Corporation, NASA MSFC and NASA Ames. We're
getting a good geographic distribution so far, but would certainly like to
have IMO members on board. If you are interested in participating, you can
register directly at the website or you can email me the following
information and I will register you in the database:

Name:
Organization:
Location: (Nearest city, State/Province, Country, Region)
Approximate latitue/longitude:
Observation type:   (Raw Visual Counts, Raw Radar Counts, Zenith Hourly Rate,
Flux)
Email Address:

The website registration is located at:
http://www.leonidstorm.com/cgi-bin/regtool.cgi

Thanks in advance for your consideration,
Glenn Peterson

HRO Today in Japan   Nov.10, 1999
Radio Meteor Data from Japan
////////////////////////////////////////////////////
Kazuhiro Suzuki,  E-mail: kazuhiro@...
URL: http://www.tcp-ip.or.jp/~kaze/rmd.htm    "Radio Meteor Data, JAPAN"
////////////////////////////////////////////////////
Observer:      Kazuhiro Suzuki
                HRO (Forward-scattered Radio Meteor Observation using HAM)
Location:      Toyokawa Meteor Observatory (137.32 deg E, 34.81 deg N)
                Toyokawa-city, Aichi, 442-0845, JAPAN
Transmitter:   JA9YDB 53.7500 MHz, CW 50 W operated by K.Maegawa
Antenna:       Dipole (height 7 m, to zenith)
Receiver:      IC-575 (ICOM)  LSB  BW 2.5 kHz
Transmitter location: Sabae (in Fukui pref.), about 150 km
                north north-west from receiving station.
Method of echo sampling: After image procedure was done by PC with FFT
software, echoes(>10 dB(S/N)) were counted.

LT   00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22
23
UT   15 16 17 18 19 20 21 22 23/00 01 02 03 04 05 06 07 08 09 10 11 12 13
14
------------------------------------------------------------------------
November, 1999
  1/  21 32 25 25 32 24 31 33 31 25 23 15 18 13 17 15 15 16@16 Es Es Es Es
Es
                   1        1
  2/  23 19 23 30 29 20 20 26 23 22 25 21 17 13@18 13 14 14@14 11 17 17
16@17
                1        1                    1  1
  3/  26 42 34 28 46 47 39 23 29@29@22 Es Es Es@18 Es Es Es 13 15 20 22
20@17
             1  1        1        1
  4/  30 33 46 42 35 40 32 31 27 31 29 17 24 22 19 Es Es@14@16 --@19 21 25@19

                   1           1     1
  5/  23 34 49 57 39 48 39 36 40 33 31 29 26 13 19 Es Es Es 14 23 17@24
Es@18
          1  1           2                    1
  6/  33 34 46 34 36 30 34@31 27 30 29 25 27 Es@20@18 Es Es Es 18@18
Es@16@21
             1  2  2     1           1           2
  7/  17 34 34 31 42 34 30 42 24 28 29 21 18 18 16 15 16 IF 16 17 27 30
24@18
                   1  1  1
  8/  24 21 36 41 36 23 26 26 20 26 IF IF Es@24 20 16 IF IF IF@13 15 IF IF
IF
       1  1              2                       1
  9/  20 35 33 39 34 30 28@27@33 30 26 29 32 21 17 21 18 20@14 18 21 31
22@19
          1  1     2     2              1
10/  25 32 42 33 35 30 41 34 40 26 33 29 31 36 Es@18 21 17 15 21
          1                 1  2  1                             1
------------------------------------------------------
@symbol means corrected hourly rate.  Es symbol means interruption by
Sporadic E layer.  IF symbol means interference by foreign broadcasting.
  up/middle/down : hourly rate of all echoes / hourly rate of long(> 20 sec.)
echoes/dead time rate(%) caused by persistent echoes

Note to readers:  if you do not have access to reference [1], please skip
sections that are incomprehensible without it.  Things such as the Table 3
predictions should be clear by themselves.


                                                      Last modified 1999 Nov 9

LEONID DUST TRAILS AND METEOR STORMS:  UPDATE

R.H. McNaught and D.J. Asher

-----------------------------------------------------------------------------

In WGN 27, 85-102 (1999), details of the Earth's encounters with Leonid dust
trails were presented.  Moderately close encounters will lead to substantial
meteor outbursts during the 1999 and perhaps the 2000 Leonids, while even
closer encounters will produce storm level activity in 2001 and 2002.  Here
we summarise the predictions of the dust trail model for 1999 and the
following few years, for the last time before observations of the 1999
Leonids afford the first test of these predictions.  The updated analysis
here is a little more comprehensive than presented previously.

-----------------------------------------------------------------------------


1. Introduction

The highest ZHR Leonid storms of the 19th and 20th centuries, as well as many
other sharp outbursts, have occurred when the Earth encountered a young dust
trail within the Leonid stream.  Such a trail is generated every 33 years or
so when Comet 55P/Tempel-Tuttle returns to perihelion.  Each trail
progressively lengthens while remaining narrow and dense (density dilution
being due to lengthening alone, not broadening) until it is scattered into
the Leonid background after a few centuries.  Readers should refer to [1] for
further details.

The predictive power of the dust trail theory is demonstrated by the
following facts.

    Storms and outbursts over the past 200 years that correspond to the
    Earth's encounter with a given young dust trail have the calculated peak
    times (i.e., based on the centre of the Earth reaching the calculated
    nodal longitude of the trail) and the observed peak times matching to
    10 minutes or less [1], in cases where the observed peak is known to
    better than that accuracy.

    A topocentric correction improves the match even further [2].  Data from
    the past 200 years now indicate that close encounters are predictable with
    an uncertainty of 5 minutes.

    The peak time of the 1998 Draconid outburst [3] was predicted equally
    accurately by Reznikov [4] using the same form of dust trail
    calculations.

    Moreover, Leonid timings relating to what we term young trail encounters
    have been independently confirmed by the Russian group that includes
    Reznikov [5,6] and by Lyytinen [7].  See [6] for references by the same
    authors describing work on other streams.


2. Update

In [1], a desire to avoid excessive effort led us to make our calculations
comprehensive (covering the past 200 years) only for trails 6 or less
revolutions old; three encounters with slightly older trails were considered
as special cases.  Also an error in the calculations caused very small
inaccuracies (less than 0.0001 AU) in the determination of trails' nodal
distances.

Now we provide an updated list of encounters (covering the next few years
only, these being of greatest interest for meteor observers) for trails up to
9 revolutions old.  Changes to the ZHR fit due to the error are not
substantial but a new fit is done.

Table 1 shows the data for past trail encounters.  The only corrections to
the entries in Tables 2 and 3 of [1] are in r_E-r_D.  Reference [1] can be
consulted for more details, but in summary, the strength of an outburst is
affected by Delta a_0 (which effectively corresponds to the ejection
velocity, this in turn being related to the mass distribution),
r_E-r_D (the miss distance of the Earth from the trail node) and f_M
(which measures the change in density due to trail lengthening).  Table 2
is for encounters over the next few years (cf. Table 5 of [1]).  Roughly,
f_M is expected to be inversely related to the age of the trail, but for
example, the value for the part of the 9-rev trail that is encountered
in 2001 shows that gravitational perturbations can cause deviations from
this simplistic relationship, after a few revolutions.

Table 1 - Past trail encounters
                                                 Observed  Calculated
Year  Trail   Node   Delta a_0  r_E-r_D   f_M    ZHR/f_M   ZHR/f_M
              (J2000)    (AU)      (AU)
1966  2-rev  235.158   +0.168  -0.00013   0.52   170,000   100,000
1833  1-rev  233.184   +0.174  -0.00021   0.95    63,000    76,000
1866  4-rev  233.333   +0.059  -0.00029   0.37    22,000    22,000
1867  1-rev  233.420   +0.373  -0.00014   1.00     4,500     4,600
1869  3-rev  233.536   +0.320  -0.00047   0.44     2,300     2,200
1969  1-rev  235.272   +0.934  -0.00004   0.95         -         -

Table 2 - Future trail encounters

Year  Trail   Node   Delta a_0  r_E-r_D   f_M
              (J2000)    (AU)      (AU)
1999  3-rev  235.291   +0.138  -0.00066   0.38
2000  8-rev  236.103   +0.064  +0.00076   0.27
2000  4-rev  236.276   +0.114  +0.00077   0.13
2001  7-rev  236.114   +0.081  -0.00043  ~0.14
2001  9-rev  236.429   +0.041  +0.00015   0.43
2001  4-rev  236.463   +0.142  +0.00022   0.13
2002  7-rev  236.610   +0.113  -0.00015   0.13
2002  4-rev  236.888   +0.172  -0.00005   0.15
2006  2-rev  236.615   +0.961  -0.00009   0.53

A model in which ZHR/f_M (ZHR being the observed peak ZHR in past encounters)
is fitted as a function of Delta a_0 and r_E-r_D, as described in [1], is
done, and applied to the future years.  The five storm years in Table 1
(1969 excluded) are used in the fit, to interpolate ZHR estimates for
1999-2002.  It is inappropriate to apply exactly the same model to very
different values of Delta a_0 and so 1969 alone is used to predict 2006 alone.
The predictions are in Table 3 (cf. Table 6 of [1]).  Only the fit centred at
r_D (cf. Tables 4 and 9 of [1]) is given, the formal uncertainty in the fit
being 20%.  Whilst the overall fit is reasonable, there is now a
discrepancy between the calculated ZHR values for 1833 and 1966.  For 1966
the calculated ZHR is 53,000.  Despite the uncertainty in the observed ZHR in
1966, it is probably one of the more reliable data points used in the fit and
1833 the least reliable.  In 1999, the formal ZHR prediction is 500 and
this appears fairly robust, regardless of whether the 1833, 1966 or both are
used in the fit, but values 200 < ZHR < 2000 give a reasonable fit.

Table 3 - Predictions

Time (UT)           Trail  Estimated  Moon   Visible from
                               ZHR     age
1999 Nov 18, 02:08  3-rev      500     10  Africa, Europe
2000 Nov 18, 03:44  8-rev       30?    22  W. Africa, W. Europe, NE S. America
2000 Nov 18, 07:51  4-rev       20?    22  N. America, Central America &
                                               NW S. America
2001 Nov 18, 10:01  7-rev    1,500?     3  N. & Central America
2001 Nov 18, 17:31  9-rev   15,000      3  Australia, E. Asia
2001 Nov 18, 18:19  4-rev   15,000      3  W. Australia, E., SE & Central Asia
2002 Nov 19, 04:00  7-rev   15,000     15  W. Africa, W. Europe, N. Canada,
                                               NE S. America
2002 Nov 19, 10:36  4-rev   25,000     15  N. America
2006 Nov 19, 04:45  2-rev      100     28  W. Europe, W. Africa

Figures 1 and 2 are the visibility maps that are not in [8].  Note that in
these figures, the Moon's phase is displayed as seen from the southern
hemisphere.

Figure 1
    (See http://www.atnf.csiro.au/asa_www/images/2001csl.gif [15Kb])

Figure 2
    (See http://www.atnf.csiro.au/asa_www/images/2002bsl.gif [15Kb])


3. Discussion

Revised values of the nodal distance required a reassessment of the ZHR
predictions from the dust trail density model.  Overall, the rates have not
changed substantially, although the uncertainty in the fit has increased.
For 1999, the predicted ZHR for the 3-rev dust trail encounter is probably of
the order of 500.  This value requires some elaboration.  Activity from this
dust trail will be additional to background activity, which could itself
have a ZHR in the hundreds.  Thus, the observed ZHR at the time of the
peak will probably lie in the range 500-1000, if the dust trail contributes
a ZHR of 500.  This value is entirely consistent with past data,
given that there are uncertainties in the past peak ZHRs used in the
fit, and different fits can be done (cf. [1]) centred on slightly different
values of r_D.

Given that some older trails have been demonstrated to be capable of
delivering high rates (e.g. the 9-rev trail of high f_M in 2001), it will be
necessary to check that for the years of the storm data used in the ZHR fit,
no additional old dust trails were contaminating the ZHR.  In future
analyses, we shall also remove the background component from the peak ZHRs,
to more truly represent the contribution of the dust trails alone.

One interesting change to the ZHR fit, is that the predicted ZHR in 1801
from the 2-rev trail is now 300.  This is much smaller than our original
predictions that suggested a minor storm had occurred.  Thus, this potential
anomaly of an unobserved storm in the last 200 years over western Europe, is
no longer a problem.  A short lived peak ZHR of around 300 would probably not
have attracted much attention in those years.  However, we are aware of no
data that refute the possibility of a storm in that year.

There are no additional encounters with trails up to 19 revolutions old in
1999; therefore, unpredicted high activity is unlikely.  There appear to be
no other encounters of significance in the following years up to this age,
although in 2001, an encounter with a disrupted 10-rev trail of uncertain
density could produce a peak ZHR of around 1,000 on Nov 18, 18:01 UT.
Although the disrupted nature of this section of the 10-rev trail makes
this time unreliable (pending more detailed simulations), it appears to be
during the 48 minute gap between the stronger encounters.  These three
encounters in close succession, with no interference from the Moon, suggest
the highest observable rates will occur in 2001, although the ZHR in 2002 is
likely to be higher.

For the 3-rev trail encounter in 1999, the time of maximum is predicted to be
at Nov 18 02:08 UT in the Mediterranean region, with an uncertainty of around
5 minutes.  The time of maximum is dependent on location [2], with the peak
predicted at 01:58 in South Africa and 02:14 in northern Scandanavia.  The
dust trail model does not make any prediction about the time or intensity of
the background activity maximum, but in the past 200 years the highest
Leonid rates outside young dust trail encounters, can approach a ZHR of
500.

Further information is available in [9].


References

[1]  R.H. McNaught, D.J. Asher, `Leonid dust trails and meteor storms.'  WGN
      27, 1999, pp. 85-102.

[2]  R.H. McNaught, D.J. Asher, `Variation of Leonid maximum times with
      location of observer.'  Meteorit. Planet. Sci. 34, 1999, pp. 975-978.

[3]  R. Arlt, `Bulletin 13 of the International Leonid Watch: The 1998 Leonid
      meteor shower.'  WGN 26, 1998, pp. 239-248.

[4]  E.A. Reznikov, `The Giacobini-Zinner Comet and Giacobinid meteor
      stream.'  Trudy Kazan. Gor. Astron. Obs. 53, 1993, pp. 80-101 (in
      Russian).  See also IMO-News mailing list, 1998 Sept 9.

[5]  E.D. Kondrat'eva, E.A. Reznikov, `Comet Tempel-Tuttle and the Leonid
      meteor swarm.'  Sol. Syst. Res. 19, 1985, pp. 96-101.

[6]  E.D. Kondrat'eva, I.N. Murav'eva, E.A. Reznikov, `On the forthcoming
      return of the Leonid meteoric swarm.'  Sol. Syst. Res. 31, 1997,
      pp. 489-492.

[7]  E. Lyytinen, `Leonid predictions for the years 1999-2007 with the
      satellite model of comets.'  Meta Res. Bull. 8, 1999, pp. 33-40.

[8]  R.H. McNaught, `Visibility of Leonid showers in 1999-2006 and 2034.'
      WGN 27, 1999, pp. 164-171.

[9]  Armagh Observatory Leonid WWW pages are http://www.arm.ac.uk/leonid/
      and general notes for the public are at
      http://www.atnf.csiro.au/asa_www/leonids.html


Acknowledgments

DJA thanks Esko Lyytinen for extremely valuable discussions on this work.


Authors' addresses

Robert H. McNaught, Siding Spring Observatory, Coonabarabran,
NSW 2357, Australia (rmn@...)

David Asher, Armagh Observatory, College Hill,
Armagh, BT61 9DG, N. Ireland, UK (dja@...)

I would like some general advice on making a scientifically useful video of
the upcoming Leonids and other meteor showers.  We have an image
intensified video system that has two different wide angle lenses that we
can use with it.  One lens is a 135 with a field of view of ~10 degrees
that reaches a magnitude of deeper than 9.  The other lens is a variable
from 28 to 70.  The field of view is from around ~20 to ~40 degrees,
limiting magnitude to be yet determined.  We could image the Andromeda
galaxy in town here in Topeka last night with it set at 70.  We record in
either S-VHS or regular VHS using very high quality tape and have GPS time
insertion.
	 Questions :  Which  lens would best for the showers?  How large a field is
optimal?  Where is the best place to aim the system?  It can and will be
mounted on a driven scope.
	 I tried to email these before but ran into delivery problems.  I look
forward to your answers.

Craig McManus
Researcher
Instrument Specialist
Kansas Flint Hills Obs. Complex
Member IOTA, AAVSO
iota@...

Dear recipients,

I noticed a small but very unfortunate typo in the introductory text of
the mailing you received earlier today:

the Leonid peak is expected around 2h UT on November 18, 1999 (2h08m UT
to be more precise, according to the calculations of Asher and McNaught),
and not 3h UT as erroneously mentioned.

The information in the attachments is correct.

Please apologize me for this slip; Murphy is omnipresent, apparently!

Kind regards,

Marc Gyssens

Greetings,

  The Arab Union for Astronomy & Space Sciences, the Institute of
Astronomy & Space Sciences, and the Jordanian Astronomical Society, will
organize the 1999 Jordanian Leonid Meteors Conference on the period
12-21 November 1999.

  Kindly visit our Leonids '99  page to know the details of this
conference, as well as the expectations of some well-known scientists.
Also, u will find several links to other related sites.  Have a look at
that page, and we appreciate ur comments.

http://www.jas.org.jo/leo99.html


Clear Skies !!
Moh'd
--
**********************************************************************
Mohammad Shawkat Odeh.
Jordanian Astronomical Society (JAS).
Member of JAS Administrative Board.
P.O. Box 925916 Amman 11110 Jordan.
Fax:  (001)(707) 221-0918.
odeh@...
http://Beam.to/odeh      (Personal URL)
http://www.jas.org.jo/   (JAS URL)
**********************************************************************

I N T E R N A T I O N A L   M E T E O R   O R G A N I Z A T I O N


                           The 1999 Leonids
                           ================

Dear Meteor Friend,

There is no need for telling you that this year's Leonids may well
produce very high activity, most likely over European longitudes,
as the most probable peak time is around 3h UT on November 18, 1999.
For your information, we provide you in attachment with the following
documents:

1. Press Release;
2. Science Note;
3. Visual Observing Hints.

In case a meteor storm materializes, it is no longer possible to
record all observing data a visual observer usually records, and,
therefore, you must make priorities. Document 3 is all about choosing
these priorities in such a way that later analyses can get the most
out of your observations, so we strongly urge you to study this!
It is a reprint of an article that appeared in the October 1999 issue
of WGN.

Furthermore, it is not unlikely that your local press may ask you
for information about the upcoming Leonid event. For this purpose,
Documents 1 and 2 (a short press release and more expanded
elaboration) may be useful. Provided proper credit is given, you are
welcome to use these documents in any manner that suits you.

Finally, note that the International Meteor Organization is currently
making arrangements to ensure, weather permitting, that reliable first
results will be available within hours after the above time. A press
release based on these results will also be forwarded to you.

Kind regards,

Marc Gyssens
Council Member

email: wgn@...
phone: +32-477-64 05 48

I N T E R N A T I O N A L   M E T E O R   O R G A N I Z A T I O N

                            Press release

Night of November 17-18: strong activity of Leonid meteors expected
===================================================================

From most of Europe, the Mediterranean area, and northern Africa,
people may see a lot of meteors - "shooting stars" - between midnight
and dawn of the night of November 17 to 18, provided skies are clear.
These meteors belong to the so-called Leonid shower. The peak of this
shower is expected around 2 a.m. Greenwich Mean Time, which is 3
a.m. local time for most of continental western and central Europe and
mid-northern and west-central Africa, and 4 a.m. local time for
eastern Europe, Turkey, Israel, Jordan, and northeast Africa. At that
time, an observer will see at least 50 to 100 meteors per hour, but
there is a fair chance that a veritable meteor storm will materialize
with 1000 or more meteors per hour around the abovementioned time.
The International Meteor Organization, who collects meteor
observations world-wide for the purpose of analysis, wishes to point
the attention of the public to this spectacular natural phenomenon.

The Leonids are caused by a stream of predominantly very small
particles, less than 1 mm in size, which orbit the Sun with a period
of 33 years, together with their parent comet, Tempel-Tuttle. The
orbit of the Leonid particles happens to intersect the Earth's
orbit. Each year around November 17, when the Earth is at this
intersection, Leonid particles may enter the Earth's atmosphere and
cause meteors, popularly called "shooting stars." This year, around 2
a.m. Greenwich Mean Time, in the morning hours of the night of
November 17 to 18, the Earth will pass through the outer regions of a
dense dust trail of Leonid particles ejected by Comet Tempel-Tuttle
100 years ago. Comparison with similar events in the past results in
an expected activity of around 500 or 1000 meteors per hour around the
abovementioned time, but these numbers are only indicative: the real
frequency may be both higher or lower! However, even if the storm
would fail to materialize, a frequency of 50 to 100 meteors per hour
is guaranteed. Should Leonid meteor activity disappoint in 1999, it is
good to know that Leonid meteor storms are possible in 2000, 2001, and
2002, too!

Actually, Leonid meteors can be seen every year around November 17.
Along the larger part of Comet Tempel-Tuttle's orbit, however, Leonid
particles are scattered sparsely, so that, in most years, we see only
a few Leonid meteors per hour. Only in the vicinity of the Comet, the
density of Leonid particles is much higher. Therefore, we observe much
higher Leonid activity every 33 years during a couple of years, when
Comet Tempel-Tuttle revisits our region of the Solar System. In some
instances, we even see a real meteor storm!

Old chronicles contain references to past Leonid meteor storms back to
the 10th century A.D. The best-known Leonid meteor storms are those of
1833 and 1966, when tens of meteors per second darted across the
skies during the peak hour! The 1833 meteor storm was so spectacular
that it in fact launched meteor research as a branch of astronomy.
Since the 1966 meteor storm, Comet Tempel-Tuttle has completed another
revolution around the Sun. The passage of the Comet through its
closest point to the Sun on February 28, 1998 marked the beginning of
a five-year period (1998-2002) during which strongly increased Leonid
meteor activity is again possible.

In 1998, a meteor storm did not materialize around the expected peak
time. The night before, however, saw an unexpected shower of very
bright meteors and fireballs. Astronomers managed to figure out what
had happened, and new computations match past Leonid meteor storms so
closely that there is good hope that the most recent predictions for
the period 1999-2002 are reliable.

The expected activity of Leonid meteors can in principle be seen from
any place in the abovementioned part of the world. Of course, the sky
must be clear and the selected observing site should preferentially be
free of light pollution; the less light, the more meteors will be seen!
Leonid meteors cannot be seen before around midnight. Hence, there is no
point in starting an observation earlier. Die-hards who do
not want to miss anything of the show should then continue to watch
until dawn. People who cannot afford to stay up that long should focus
on the period between 1:30 a.m. and 3 a.m. Greenwich Mean Time.

Mind that it can be very cold in mid-November: warm clothing adapted
to the local climate is essential! For comfortable observing, use a
reclining chair, and install yourself in a suitable sleeping bag or
under several blankets. While observing, do not fix a particular star,
but look relaxedly and patiently to a wide area of sky and wait
for shooting stars to appear.

------------------------------------------------------------------------

More information on the Leonids can be found in the International
Meteor Organization's bimonthly journal WGN and on the internet, at
http://www.imo.net.

For questions, contact Marc Gyssens at wgn@... or +32-477-64 05 48.

Notice that the International Meteor Organization will send out a new
release with first results on the Leonids during the European early
morning hours of November 18, immediately after the event. All
recipients of the present release will automatically receive the new
release.

I N T E R N A T I O N A L   M E T E O R   O R G A N I Z A T I O N

                            Science Note

Night of November 17-18: strong activity of Leonid meteors expected
===================================================================

SUMMARY - From most of Europe, the Mediterranean area, and northern
and west-central Africa, people may see a lot of meteors - "shooting
stars" - between midnight and dawn of the night of November 17 to 18,
provided skies are clear.  These meteors belong to the so-called
Leonid shower. The peak of this shower is expected around 2
a.m. Greenwich Mean Time, which is 3 a.m. local time for most of
continental western and central Europe and mid-northern and
west-central Africa, and 4 a.m. local time for eastern Europe, Turkey,
Israel, Jordan, and northeast Africa. At that time, an observer will
see at least 50 to 100 meteors per hour, but their is a fair chance
that a veritable meteor storm will materialize with 1000 or more
meteors per hour around the abovementioned time.  The International
Meteor Organization, who collects meteor observations world-wide for
the purpose of analysis, whiches to point the attention of the public
to this spectacular natural phenomenon.

[Numbers between brackets refer to the glossary section.]

1. THE LEONIDS
    -----------
    The Leonids are caused by a stream of predominantly very small
    particles, less than 1 mm in size, which orbit the Sun with a
    period of 33 years, together with their parent comet (1),
    Tempel-Tuttle. The orbit of the Leonid particles happens to
    intersect the Earth's orbit. Each year around
    November 17, when the Earth is at this intersection, Leonid
    particles may enter the Earth's atmosphere and cause meteors (2).
    Along the larger part of Comet Tempel-Tuttle's orbit, Leonid
    particles are scattered sparsely, so that, in most years, we see
    only a few Leonid meteors per hour. Only in the vicinity of the
    Comet, the density of Leonid particles is much higher.
    Consequently, every 33 years, during the years that Comet
    Tempel-Tuttle revisits our region of the Solar System, much higher
    Leonid activity is recorded. In some instances, this Leonid meteor
    shower develops into a real meteor storm!

2. LEONIDS IN THE PAST
    -------------------
    Old chronicles from all over the world (European, Arab, Chinese,
    Korean, Japanese, American, ...) contain references to past Leonid
    meteor storms back to the 10th century A.D.

    Well-documented observations of Leonid meteor storms
    go back only to 1799, when the great German explorer and naturalist
    Alexander Von Humboldt, rather coincidentally, witnessed a Leonid
    meteor storm from Venezuela. The same spectacular phenomenon was
    also observed from Florida.

    However, the 1833 Leonid meteor storm had a far greater impact on
    the public and the scientists alike, mainly because it was visible
    in a much more densely populated area, namely New England.
    At its peak, tens of meteors crossed the sky each second! Pious
    Christians believed that Judgment Day had broken and many who
    witness this celestial fireworks compared it to a snow storm!
    Because of the interest it had sparked, this particular Leonid
    meteor storm turned out to be very instrumental for the development
    of meteor astronomy.

    A somewhat less spectacular Leonid meteor storm occurred in 1866;
    around 1899 and 1933, there was increased Leonid meteor activity,
    but no storm.

    In 1966, however, the Leonids returned in full splendor: observers
    at Kitt Peak in Arizona saw a Leonid meteor storm peaking with
    no less than approximately 40 meteors each second, which amounts
    to a frequency of 150 000 meteors per second!

3. LEONIDS TODAY
    -------------
    Since the 1966 meteor storm, Comet Tempel-Tuttle has completed
    another revolution around the Sun. The passage of the Comet through
    its closest point to the Sun on February 28, 1998 marked the
    beginning of a five-year period (1998-2002) during which strongly
    increased Leonid meteor activity is again possible. Whether or not
    a meteor storm actually materializes in any or all of these years
    depends on several circumstances, on which we will briefly
    elaborate.

4. WHEN DO STORMS MATERIALIZE?
    ---------------------------
    Meteor showers (3) are caused by small particles orbiting the Sun,
    in most cases released by comets. Each time a comet passes the Sun,
    it  releases "dust" particles (as well as gasses), in the case of
    Comet Tempel-Tuttle every 33 years. As a first approximation, we may
    compare this dust production to the condensation trail of a jet
    plane. Like a condensation trail, a dust filament released by a
    comet fades away over a period of a few centuries until it can no
    longer be distinguished from the dust around the comet that was
    released much longer ago. Only if the Earth passes through a dust
    particle filament released by the comet at most 7 or 8 revolutions
    ago, in the case of Comet Tempel-Tuttle less than about 250 years
    ago, will a veritable meteor storm occur.

    Every 33 years, when the Comet passes the Sun, there is a "window"
    of about 5 years in which the Earth may pass through one or more
    "young" dust particle filaments. When this happens, we see a storm
    of between about one thousand and more than one hundred thousand
    meteors per hour, lasting at most one hour. The actual peak of the
    activity is often of even shorter duration. The precise frequency
    depends on the age of the filament and whether the Earth goes
    straight through the core of this filament, or only through its
    outer regions. If the Earth misses all young dust particle
    filaments, the older dust particles around the comet will give rise
    to a more modest meteor shower producing 50 to 100 meteors per hour.

5. WHEN DO WE SEE LEONID METEORS?
    ------------------------------
    Around November 17, Leonid particles may enter the Earth's
    atmosphere from a direction - called the radiant (4) located in the
    head of the constellation of Leo, the Lion, from which the shower
    derives its name. Because Leo is below the horizon in most of the
    first half of the night, we can only see Leonids past midnight.
    From one particular location, a possible Leonid meteor storm is
    only visible if peak activity occurs between midnight and dawn.
    In addition, you need a clear sky, which is not for granted
    around mid-November ...

6. WHAT HAPPENED IN 1998?
    ----------------------
    During the first morning hours of November 17, 1998, early birds
    witnessed a veritable fireball (1) storm: during a typical hour,
    100 to 200 very bright meteors appeared. These meteors were even so
    bright, that the spectacular show could be followed well into dawn.
    During the night of November 17 to 18, when peak activity was
    supposed to occur, many casual observers around the world saw
    nothing at all ... a "miscalculation" of the astronomers, as some
    reported?

    The fireball storm in the morning of November 17 came as a complete
    surprise. Later calculations showed that large dust particles
    released by the Comet 6 to 7 centuries ago were responsible for
    this phenomenon. Normally, dust particle filaments that old have
    completely faded away and are incapable of producing significantly
    enhanced activity. In this case, astronomers have shown that the
    gravitational pull of the giant planet Jupiter managed to keep at
    least the larger dust particles together. Other forces cause the
    smaller dust particles to disperse much more easily than the larger
    ones - this explains why so many fireballs and so few weaker
    meteors were seen.

    The "actual" storm - if at all a storm were to materialize - was
    expected on November 17 around 8:30 p.m. Greenwich Mean Time. At
    that time, it was early afternoon in the Americas, while Europe and
    Africa were in the first half of their night of November 17 to 18.
    Hence, it was impossible for the people on these continents to see
    a Leonid meteor storm there, but this message failed to reach many
    of them, causing disappointment that could have been avoided.
    Central Asia, however, was in the second half of its night of
    November 17 to 18, and several observers have set up expeditions to
    China, Mongolia, and Siberia. Unfortunately, a meteor storm did not
    materialize. At their peak, the Leonids showed no more than 100 to
    150 meteors per hour. Later calculations revealed that the Earth
    had missed all young dust particle filaments.

7. WHAT MAY BE EXPECTED THIS YEAR?
    -------------------------------
    The calculations made after the 1998 Leonid event referred to in
    the previous paragraph and comparisons with observations of
    previous Leonid events have demonstrated that it is possible to
    accurately predict whether or not the Earth will pass through a
    young dust particle filament of Comet Tempel-Tuttle.

    The calculations for 1999 indicate that the Earth will pass through
    a dust filament of one hundred years old, released by the Comet
    three revolutions ago. This is expected to occur around 2 a.m.
    Greenwich Mean Time on November 18, i.e., from most of Europe, the
    Mediterranean area and northern and west-central Africa during the
    second half of the night of November 17 to 18! Unfortunately, the
    Earth will not pass through the core of the filament, but rather
    through its outer regions. Comparison with similar events in the
    past results in an expected activity of around 500 or 1000 meteors
    per hour around the abovementioned time, but these numbers are only
    indicative: the real frequency may be both higher or lower!
    However, even if the storm would fail to materialize, a frequency
    of 50 to 100 meteors per hour is guaranteed.

    A recurrence of a fireball storm the night before is highly
    unlikely.

8. WHERE AND WHEN TO LOOK
    ----------------------
    As explained above, a Leonid meteor storm this year, if it
    materializes, will only be visible from most of Europe, the
    Mediterranean area, and northern and west-central Africa. In this
    part of the world, 2 a.m. Greenwich Mean Time corresponds to 2 a.m.-4
    a.m. local time. To see any activity, people there must either stay
    up long on November 17 or raise early on November 18. At least
    50 to 100 meteors per hour will be visible; if a storm
    materializes, meteor counts can go up to 1000 or more per hour.

    However, much is going to depend on the weather that is unstable
    over all Europe and the Mediterranean area in that time of year.
    The deserts in the Middle East (Israel, Jordan, ...) may be a good
    choice, except if the peak occurs significantly later than
    expected. In western Europe, the French Provence and Southern Spain
    are among the best places. In Africa, the probability of clear
    skies increases dramatically the more you move away from
    Mediterranean influences, and the more you move toward Saharan
    influences. The Canary Islands also offer good perspectives,
    provided you climb to altitudes which are above the clouds and
    provided the peak does not occur significantly earlier than
    expected. Climate-wise, most of Mediterranean coast, including the
    North-African part, is to be avoided.

    However, climate is only what you expect, and weather is what you
    get! Therefore, the best strategy to avoid bad weather is closely
    following the weather charts and travel one day in advance to the
    location within your "action radius" that offers the most favorable
    prospects.

    Whether you choose to travel or stay at home, you will have to wait
    and see until the last moment if weather conditions will be
    favorable - a patch of clouds or a clearing at the right time can
    create a world of difference!

    Besides weather, light pollution is an important factor in choosing
    an observing sight. Despite last year's fireball storm, most
    Leonids are not that bright. The more light pollution, the fewer
    meteors you will see! So, choose a dark spot!

    As explained above, Leonid meteors cannot be seen before midnight.
    Hence, there is no point in starting an observation earlier.
    However, die-hards who do not want to miss anything of the show
    should then continue to watch until dawn. People who cannot afford
    to stay up that long should focus on the period between 1:30 a.m.
    and 3 a.m. Greenwich Mean Time.


9. HOW TO WATCH?
    -------------
    Mind that it can be very cold in mid-November: warm clothing
    adapted to the local climate is essential!

    Since you can never tell in advance at what precise time at which
    direction in the sky a meteor will appear, you should never fix a
    particular star, but rather patiently watch a wide area of sky in a
    relaxed way until a meteor appears. It is not necessary to look in
    the direction of the constellation of Leo: you will see meteors all
    over the sky, in all directions.

    For comfortable observing, use a reclining chair, and install
    yourself in a suitable sleeping bag or under several blankets.

10.LEONIDS AFTER 1999
    ------------------
    Leonid meteor storms may occur in 2000, 2001, and 2002 as
    well. According to the most recent predictions, a Leonid storm of
    roughly the same strength as expected this year may be visible from
    roughly the same area of the world in the morning hours of November
    18. The best prospect for the 1998-2002 Leonid "window" are for
    2001, however.  That year, a Leonid meteor storm in the order of
    magnitude of ten thousand meteors per hour may materialize over
    Australia, Japan, the western Pacific and eastern Asia. A similar
    event will occur over North America in 2002; unfortunately, this
    event will be partially spoiled by the light pollution of a Full Moon.

GLOSSARY AND ADDITIONAL EXPLANATIONS
------------------------------------

(1) COMETS - Comets are small celestial bodies (with a diameter
     varying from a few kilometers to at most a few tens of kilometers)
     that revolve around the Sun in long elliptical orbits.
     Comets consist mainly of ice and dust. When a comet approaches the
     Sun, part of the ice will evaporate and, because of the resulting
     pressure, the gas will find its way through cracks and fissures in
     the thin comet crest and be ejected under the form of "geysers."
     The evaporated ice of these geysers will feed the coma and the tail
     of the comet. Together with the evaporated ice, a lost of dust is
     released. This dust eventually spreads along the entire orbit of
     the comet, but remains densest in its immediate vicinity. Meteoroid
     streams (4) usually consist of cometary dust.

(2) METEORS - Dust particles orbiting the Sun and capable of
     "colliding" with the Earth are called meteoroids. Such a
     meteoroid has usually the size of a sand grain or a tiny stone.
     When it enters the atmosphere, with typical velocities of a few
     tens of kilometers per second - several then thousands of
     kilometers per hour! - not only the meteoroid but the surrounding
     air experience enormous friction. This friction causes the air
     surrounding the meteoroid to give light, in much the same way
     as an electric current causes the gas in a TL lamp to give light.
     Meteors typically light up at heights of 90 to 110 kilometers. The
     resulting light is called a meteor or a shooting star. Usually,
     the enormous friction causes a meteoroid to disintegrate into the
     molecules it is composed of: the meteoroid "evaporates"
     completely. Only the larger and stronger meteoroids may survive
	 traversing the atmosphere. The remainder of the meteoroid that
	 impacts on the Earth is called a meteorite. Leonids are too
	 fragile to produce meteorites, even if they are meter-sized.

     Occasionally, meteors are exceptionally bright, brighter that the
     brightest planets, and sometimes even brighter than to Moon. These
     meteors are called fireballs.

(3) METEOROID STREAMS AND METEOR SHOWERS - The collection of particles
     released by a comet (or comet-like asteroid) is called a meteoroid
     stream. The meteor display in the sky caused by a meteoroid stream
     is referred to as a meteor shower, or, in case of extremely high
     activity, a meteor storm.

     Meteoroid streams and their associated meteor showers are named
     either after the comet from the particles originate, or, as is the
     case for the Leonids, after the constellation in which its radiant
     (4) is located.

     The Leonids are not the only meteor shower we can see. In fact,
     their are dozens of other meteor showers, but most of them never
     produce more than a few meteors per hour. Two notable exceptions
     are the Perseids, active around August 12, and the Geminids,
     active around December 14. Every year, both showers produce
     several tens of meteors per hour at their respective peak times.

     Finally, we must mention that the Solar System contains a lot of
     dust particles that do not belong to any particular meteoroid
     stream. These particles cause so-called sporadic meteors, which
     may appear any time.

(4) RADIANT - Meteoroids of the same stream (3) orbit the Sun along a
     common orbit (roughly the orbit of the comet from which they
     originate). When the Earth crosses a meteoroid stream, our planet
     is "hit" by a "bombardment" of dust particles which all come
     from the same direction. The perspective, however, leaves us the
     impression that the meteor trajectories in the sky, when prolongated
     backward, originate from a single point, just like the tracks of a
     long, straight railroad. This point is called the radiant of the
     meteor shower. Most meteor streams and showers are named after the
     constellation in which this radiant is located. Even though the
     backward prolongations of all meteors of the same shower intersect
     the radiant, the meteors themselves can appear anywhere in the sky.
     Hence, there is no need to look in the direction of the radiant to
     observe a meteor shower.

     To understand better what happens during a meteor shower, picture
	 the stream orbit as a "race track" along which all meteoroids race
	 at the same speed. Picture the Earth, with yourself as an observer
	 on the Earth, as an "unexpected" obstacle on this race track with
	 which meteoroids may collide, producing meteors in the process.
	 If you look in the direction of the radiant, you will only see
	 short meteors, caused by meteoroids colliding with the Earth's
	 atmosphere while "running" almost straight toward you. If you look
	 at 90 degrees from the radiant, you will see long meteors, caused
	 by meteoroids colliding with the Earth's atmosphere just when they
	 were about to overtake you. If you watch even further away from
	 the radiant, you will again see shorter meteors, caused by
	 meteoroids colliding with the Earth's atmosphere after they had
	 passed you, and thus moving away from you.

------------------------------------------------------------------------

More information on the Leonids can be found in the International
Meteor Organization's bimonthly journal WGN and on the internet, at
http://www.imo.net.

For questions, contact Marc Gyssens at wgn@... or +32-477-64 05 48.

Notice that the International Meteor Organization will send out a new
release with first results on the Leonids during the European early
morning hours of November 18, immediately after the event. All
recipients of the present note will automatically receive the new
release.

I N T E R N A T I O N A L   M E T E O R   O R G A N I Z A T I O N

Hints for visual 1999 Leonid observations
=========================================

by Rainer Arlt

1. INTRODUCTION
    ------------
    Summarizing the predictions in short, we expect a strong, narrow
    outburst of Leonids in November 1999. Since the behavior of the
    1998 Leonids and that of many previous years and epochs can be
    reconstructed with particle models in impressive agreement with the
    observations, the prediction following from the same models are
    thought to be quite accurate, too (see, e.g., [1,2] for such
    models). According to [3], a to-the-minute prediction is possible
    for November 18, 2h08m Greenwich Mean Time. This is the time of
    passing the closest dust trail which was ejected by the parent
    Comet 55P/Tempel-Tuttle in 1899. Meteoroids from other epochs will
    add to this picture, but strongest activity is expected for this
    time with no larger deviation than one hour according to the fully
    independent study in [2]. The maximum ZHR is supposed to be of the
    order of 1000, but half or twice this value is easily possible,
    since the prediction of rates is most difficult. Maximum visible
    rates under a magnitude +6.5 sky will range from almost 15 meteors
    per minute as seen from the Near East to about 5 meteors per minute
    on the Canary Islands where the radiant is significantly lower.

2. THE OBSERVATION
    ---------------
    In case of very high rates, you will run into problems of noting
    shower and magnitude information for each meteor. First, drop the
    shower information from your log. The contamination by sporadic
    meteors will be negligible, whereas the magnitude information is
    most essential for understanding the Leonid meteoroid stream.
    Try to report magnitudes for each meteor as long as possible.
    Your notes, whether on tape or on paper, will just be a sequence
    of numbers - the magnitudes - plus regular time marks (see below).

    As it is highly probable that the main activity will be caused by
    particles recently ejected from the comet (1899 is only three
    revolutions ago), we expect a lot of faint meteors in the shower.
    An abundance of meteors might reduce the attention of the observer
    to the nicely bright meteors (which will be numerous, even though
    the population index may be high). Please keep up your
    vigilance even if the show suggests you to just "sit back."

    Limiting magnitude estimates will be difficult during an
    outburst. At least, you should obtain a limiting magnitude estimate
    shortly before and a limiting magnitude shortly after the
    outburst. If the conditions change during extraordinary activity,
    you may note relative measures like "Lm reduces by 0.1" simply
    according to your impression. Another possibility is a short break
    in your observation for limiting magnitude determination. This is
    certainly the more accurate way, though we will lose a minute or
    two in recording meteors, which is not considered to be a dramatic
    loss.

3. THE OBSERVING REPORT
    --------------------
    If a strong Leonid outburst materializes, we will experience
    very quick changes in the visible rate of meteors. The information
    of the activity profile should not be smeared out by choosing
    observing periods that are too long. Be sure to have enough time
    marks in your notes. If the rate reaches 3 meteors a minute or more,
    you can talk on your tape-recorder in real time, that is, without
    stopping the device. You are then free to make observing periods of
    down to a minute duration after your observation. Since the
    recording and replay speed may not be exactly the same, you should
    speak a few time marks (say every 10 minutes) onto your tape for
    calibration.

    A perfect observing report will list short periods with
    less than 10~meteors each. If the ZHR goes beyond 1000, it might
    be possible that you will report periods shorter than a minute.
    In a similar way, magnitude distributions should contain about
    20 meteors, seen in a period of possibly as short as two minutes
    (if you manage to speak magnitudes for all meteors on the tape).
    Remember that your individual count for such short periods may not
    look significant, but the combination of many of these periods
    reported by many observers at the same time, will yield precise
    values for the shower's population index and activity in high
    temporal resolution.

    Please, do not forget to give the main direction of your field of
    view, which is necessary to reduce meteor numbers to actual spatial
    number densities of meteoroids in the stream, or to flux
    densities. Field centers should not be chosen below 50 degrees
    elevation.

    Remember that the cloud cover factor refers to the field of view
    only, not to the entire sky, since we wish to correct only the
    individual observer's rate, not that of the entire sky. The typical
    field of view in which 98 percent of the meteors are seen has a
    diameter of roughly 100 degrees. If clouds appear behind you
    or near the horizon, not affecting your field, you should not give
    an obstruction correction in the observing report.

    We will be grateful if you send your reports to the
    IMO Visual Commission, c/o Rainer Arlt, Friedenstrasse 5,
    D-14109 Berlin, Germany, or by electronic mail to
    arlt@... (avoiding possible system overload at the
    IMO server).

REFERENCES
----------
[1] D. Asher, M.E. Bailey, V.V. Emel'yanenko, "Resonant meteoroids
     from Comet Tempel-Tuttle in 1333: the cause of the unexpected
     Leonid outburst in 1998," Mon. Not. R. Astr. Soc. 304, 1999,
     pp. L53-L56.

[2] P. Brown, Ph.D.~Thesis, Univ. of Western Ontario, London, 1999.

[3] R. McNaught, D. Asher, "Leonid Dust Trails and Meteor Storms", WGN
     27:2, April 1999, pp. 85-102.

------------------------------------------------------------------------

More information on the Leonids can be found in the International
Meteor Organization's bimonthly journal WGN and on the internet, at
http://www.imo.net.

The above article was taken from WGN 27:5, October 1999, pp. 235-236.

For questions, contact Marc Gyssens at wgn@... or +32-477-64 05 48.

Notice that the International Meteor Organization will send out a new
release with first results on the Leonids during the European early
morning hours of November 18, immediately after the event. All recipients
of the present article will automatically receive the new release.

The following are notes were started as preparation for a lecture.
However I felt that they might be of general interest, given that
many of the works cited below often go unmentioned, or are quoted
without analysis.  I am aware that I have not mentioned some works
(e.g. Kresak's 1993 study), but will include these at a later date.
As I'm leaving for overseas in several hours, my attempts to knock
this into better shape has come to an end.  Despite many
helpful comments by David Asher on a much earlier draft, about half
of what follows has not been submitted to anyone or comment.
It would thus be inappropriate to quote anything from what follows
as if it were from a refereed journal.  It is my intention to work
on this much more after my return from the Leonids trip and submit
it for publication.


A Review of Theories for Leonid Storm Prediction
R. H. McNaught,   last edited 99Nov09

Introduction
There has been little critical evaluation of the various Leonid storm
predictions, either in the professional literature or in the popular
astronomy media.  This has resulted in speculative methods with no
theoretical basis or historical validation, being presented side by side
with theoretically rigorous approaches that have been carefully validated
against the historical record.  I shall discuss some of these methods
here, so that a clearer assessment can be made about the various
prediction methods.


Studies using the comet node.

Yeomans (1981) demonstrated an obvious correlation between the timing of
storms and the time and position of the Earth in relation to the comet
node.  In terms of predictive power this model fails, with years
of high and low activity intermixed.  It is also only an approximation, as
the nodal distance of the comet is only of physical relevance when the
comet is actually at the node.  Differential perturbations between the
comet, and the ejected dust, lead to the dust having a different nodal
longitude and distance from the comet.  Also, should one choose the
osculating orbit at the time of the comet being at the node, or the time
of observation?  The value of the dust node need only be the same as the
comet at the time of ejection.  Beyond that, the orbits must be treated
independently.  Using the node of the comet gives an approximation of the
time of storms to a few hours for storms in the last 200 years, using
nodal values of either osculating orbit.  This is discussed more fully in
McNaught (1999).

That the storm years, do indeed cluster in one quadrant of the Yeoman's
plot indicates that it does have some predictive value, but there are
both false positives and flase negatives.  Although both axes of the plot
are qualitatively reasonable, only the time axis is also quantitative.
The effect of solar radiation pressure is to push particles into longer
period orbits, and therefore they return after the comet.  The density
of the dust with age since ejection but this is not accommodated in the
diagram.  The radial distance axis is problematic, as noted above.  David
Asher comments "as for the inside/outside distance being a factor, while
the idea is qualitatively correct (i.e. radiation pressure does tend to
cause particles to be on marginally bigger orbits in space) it's
qualitatively irrelevant, compared to the effect on the nodal distance
of gravitational perturbations, for visual meteor size particles."

Cooke (1997) looks at the Yeomans' diagram through a statistician's eye.
He tries to derive probabilities of storm conditions in various years.
To some extent this must be seen as a failure of this general approach
using the comet node.  No amount of math can compensate for not undertaking
a rigorous dynamical analysis of the ejected dust.  To understand Leonid
storms, or any physical phenomenon for that matter, one needs both maths
and a physical understanding of the phenomenon involved.

Ferrin (1999) uses a similar form of analysis as Yeomans, but gives the
Yeomans diagram an additional dimension of ZHR intensity at maximum.
Whilst one can argue about the values of ZHR used in the diagram (e.g.
the almost certainly spurious storm values for 1900 and 1901), and the
way individual values were selected from the available data (e.g. 1866
and 1867) the idea is initially reasonable, given the limitations noted
for the Yeomans (1981) paper above.  The intensity of the Leonid activity
of the last 200 years has isolines of shower intensity empirically fitted.
A "ridge" of uniform high intensity (ZHR = 150,000) is identified crossing
the diagram in a curve from the comet.

Given the small amount of data for high intensity storms (ZHR > 10,000),
it is notable that one of these lies significantly away from the ridge
and is too high by a factor of 10 over the fit.  Given that the fit is
completely empirical, this is a major problem for such sparse data.
Probably the most unusual thing about the fit is the assumption that the
ridge of high intensity is of uniform intensity.  This is clearly false
in the close vicinity of the comet.  The ZHR immediately beside the comet
would be enormous, such dust hardly having time to dissipate.  However
there is a big difference between the dust density near the comet and
that a year or so behind.  It is well known that solar radiation pressure
causes particles of the size that produce visual meteors, to orbit more
slowly.  Thus an initially uniform ejection of dust will, one revolution
later, result in a mass separation with most "visual meteoroids" being
concentrated away from the comet.  Thus, even with the probably spurious
storm level values for 1900 and 1901, these facts immediately suggests to
the eye a series of closed loops off-centered from the comet.  The
consequence of this would be that the rates during the current epoch
would be considerably lower than the values Ferrin suggests, from his
unjustified empirical fit.  Whilst a number of theoretical considerations
are made, there is no attempt to look at the actual spatial distribution
of dust through rigorous orbital integrations.

Brown (1999) has analysed the available historical observations of the
Leonids, deriving the time and ZHR of maximum and the width of Leonid
activity.  This represents a major achievement and all Leonid storm
prediction method should be demonstrated to be consistent with this
historical data.  Utilising this data Brown uses the same idea as
Ferrin, but allows a contour plotting program to contour the ZHR data.
For the limitations presented above, and the reasons given below, the use
of the comet node cannot succeed. The fundamental reason is that the dust
behaves independently of the comet and detailed dynamical studies of the
ejected dust must be used.


Dynamical studies of ejected dust

Wu and Williams (1996) present an analysis of the orbits of dust ejected
from comet 55P/Tempel-Tuttle.  They apply rigorous corrections for
planetary perturbations.  Part of their argument is that high ejections
velocities of several hundred metres/sec are necessary to produce the
orbits of observed Leonid meteors in 1965-66.  These orbits remain stable
over the past 100 years and do not converge to a common origin.  This is
in stark contrast to their later modelling where they assume the activity
in 1933, 1966, and predictions for 1998-99, can be based solely on dust
ejected from the comet on the previous two revolutions.

Using the high velocities of ejection derived from the meteor orbits,
they believe particles can be ejected into orbits as short as 17 years or
as long as 120 years. This provides pathways for particles to make one,
two or three revolutions in 66 years.  However, if Leonid activity is
dominated by recently ejected particles, then the meteor orbits should
converge to the comet orbit at either of the previous two returns.  That
they do not indicates that either
a) the orbits are too uncertain to be useful in this analysis and/or
b) the assumption that activity is dominated by the most recent returns
of the comet, is false.

If we assume for the moment that these high ejection velocities are
possible, it is reasonable to assume that the extreme orbits of both
shorter and longer period are likely to be significantly less populated
than those closer to the orbital period of the comet.  They specifically
make this point in section 4. This is most important when they come to
assess the number of test particles that pass close to the Earth.  They
take 20 test particles from one revolution of the comet earlier, with a 33
year period and 60 from 2 revolutions of the comet earlier, 20 each from
particle periods of 22, 33 and 66 years.  Simple summing of these 80
particles has no validity.  It is probable that there will be many more
particles with periods of 33 years than 22 or 66 years.

The orbits they integrate have starting orbital periods that make an integral
number of revolutions during the time taken for one or two comet orbits.
However, despite a claim that they did, there is no evidence in their work
that they have iterated these orbital periods to correct for changes due to
planetary perturbations resulting in the particles not arriving at the
node at the same time as the Earth.  The nodal distance is irrelevant
if the particle orbit cannot produce a close approach to the Earth.
Looking at their Fig 7, the last two bars for each year give the relative
number of particles within a nodal distance of 0.002 AU and within a
distance from the Earth of 0.005 AU.  If the correct orbital
period is chosen, then the closest approach will always be (slightly)
inside the nodal distance, so the bar giving passage within 0.005 AU
of the Earth must always be equal to, or greater than, the bar showing
particles within 0.002 AU nodal distance.  In two of the four cases they
are less, one substantially.  Thus most test particles do not in fact have
the correct period to have a close encounter with the Earth, and the
integrated particles are irrelevant in determining the approach distances
and relative numbers.    It was found by McNaught and Asher (1999)
(see below) that the density of dust trails can vary substantially on
scales of the order of an Earth diameter, so the bin sizes used are
substantially too coarse to be useful indicators of storm activity.  Any
conclusions based on Fig 7 are necessarily invalid.

Even assuming the Figure is valid, the comparison of these relative
numbers of particles for various years shows 1933 coming in at a little
under 10% of 1966, in the important quantities (number of particles with
nodal distance near Earth, and number with small distance of closest
approach to the Earth).  However, the ZHR in 1933 was around 3 orders of
magnitude smaller than in 1966 (Brown (1999)), so their statement that
these figures "roughly mirror the observations" really has little meaning.

Overall, the assumptions behind this work are reasonable, but in
restricting the calculations to only the previous two orbits, and not
choosing the precise orbital period to make a close encounter, the work
has no validity as a predictive tool.  Also they do not attempt to
derive the time of storms from the nodal longitudes of the dust orbits.
This is a necessary test of any theory, as it would have available some
of the best data for comparison.

Kondrat'eva and Reznikov (1985) were the first group to determine
meteoroid orbits that had the precise orbital period to arrive at their
descending node at the same time as the Earth.  Their work has been
largely overlooked.  The idea is extremely simple.  The only meteoroids
we can experience as meteors, are ones that have an orbital path from
the comet at or near perihelion, to the Earth in some specific November.
The application of rigorous planetary perturbations and the consideration
of solar radiation pressure, give a nominal orbital solution from which
the nodal longitude and distance is derived.  Meteoroids with any other
orbital period don't pass the node at the same time as the Earth and thus
could not become meteors.  It is the component of the ejection velocity
along the comet's velocity vector that causes the change in orbital
period.  The spread of the meteoroids about this nominal solution are a
result of other components of the ejection velocity that are orthogonal
to the comet's velocity vector and of solar radiation pressure.

Their work shows a great consistency with the historical data for the
years presented.  Their predicted time for 1966 is exact, to the
resolution of their prediction, which is 0.01 day.  In 1993, Reznikov
predicted the time of Giacobinid activity as 1998 Oct. 08.550 UT.
This was confirmed within observational error!  Clearly the group had
the ability to make predictions with high time resolution.

Kondrat'eva, Murav'eva and Reznikov (1997) update this work by extending
for dust ejected at earlier passages of 55P/Tempel-Tuttle through
perihelion and derive the nodal longitudes and distances for the dust
during the period 1760-2002.  Curiously, they only give the predictions
of the time of maximum activity to one decimal of a day (+/- 1.2 hours).
There is an exceptionally strong correlation between the close
approaches to dust "swarms" with moderate ejection velocities (<40 m/s),
and years with observed storms.  All their derived times for the storm
years agree with the observed times derived by Brown (1999) to within
+/- 1 hour.  This was clearly a major advance in Leonid storm prediction.

Asher (1999) was unaware of the Kondrat'eva et al. studies when he
basically replicated their early work with his own similar technique.
However, he did this with higher precision in nodal longitude than the
later Russian study. This led to the realisation that the derived times
from the "dust trail" nodal longitude were almost identical to the times
of Leonid storm maxima derived by Brown (1999).  This was initially
discussed by McNaught (1999).

McNaught and Asher (1999a) extended the Asher (1999) results by looking at
dust trails up to 6 revolutions old (plus some older trails identified
by Kondrat'eva et al. (1997)).  This indicated that the times of maxima
were consistent to within +/-10 minutes for all storms and short duration
outbursts that had well defined times of maximum (1866, 1867, 1869, 1966
and 1969.  Additionally, they derived a density model based on the
ejection velocity (change in semi-major axis) required to produce passage
close to the Earth and the nodal distance of the dust trail.  This
approach also took into account the mass distribution of the ejected
dust encountered in a specific year (which is correlated with ejection
velocity) and the dilution of the trail density with age.  It was
demonstrated from test integrations of dust ejected isotropically from
the comet, that the resulting trail width remains essentially constant
over several revolutions, dilution of the trail density being by
stretching alone.  Using this model of trail density, they were able
to show a remarkable consistency (+/- 20%) between the calculated
relative density and the observed ZHR for the storm data of 1833, 1866,
1867, 1869 and 1966.  Earlier storm years were not included due to poor
data quality and contamination from additional dust trails.  The fit to
the data was by a double Gaussian.  This will limit the predictive value,
as it is believed that the dust trails are not symmetrical in radial
distance mostly due to the action of solar radiation pressure.  Until a
theoretically derived dust trail profile in radial distance is developed,
the data is too sparse to suggest what improvement may be achieved.

McNaught and Asher (1999b) derived a topocentric correction for the
observer being offset from the center of the Earth which had been used
in the earlier calculations.  This indicated that the times calculated
from the dust trails could be improved from +/-10 minutes to +/-5 minutes
against the observed times calculated by Brown (1999).

Lyytinen (1999), unaware of the Kondrat'eva et al. and Asher and McNaught
studies, came up with the same results, but a very different starting
point.  Using van Flandern's satellite model of comets, he derived the
times of closest encounter with dust trails through to 2007.  Despite that
radically different initial assumption, the dynamical analysis was done
rigorously and the results of the time of maximum agreeing within minutes
with the results of the earlier studies.  Lyytinen himself did not do any
rigorous historical validation, but his results were clearly very
consistent with the historical data.

All three groups (Kondrat'eva et al., Asher and McNaught, and Lyytinen)
found a small number of dust trail encounters missed by others.  These
were mostly of older trails.  Calculations by other groups confirmed
these.

This "dust trail" approach to predicting Leonid storms is clearly very
powerful and has demonstrated a very close correspondence to the time
of storms (+/-5 minutes) and to their ZHR (20% error in the fit to 5
storm ZHRs).


Background activity.

Although one work of Brown (1999) was mentioned above, he and collegues
including Jones, have continued with their studies of the Leonid stream
as a whole.  The above dynamical studies only addressed the storm peak,
whereas Brown et al. are not considering storms in isolation.  As I have
not seen their latest work, I can only comment on what I believe is their
current approach.  By ejecting meteoroids (using an ejection model they
derived) over a period around perihelion and for many revolutions of the
comet into the past, they try to derive the overall activity of the Leonid
shower.  This requires substantial computing power, but is probably the
only way to approach the overall structure.  The limitation in this method
may be that it lacks adequate temporal and spatial resolution.  One could
liken this approach to a general geological survey of an area where
sampling at coarse intervals can miss narrow dense veins.  It may however
be the case that the resolution is adequate to identify the dust trails,
although the results presented by Brown el al. earlier this year do not
confirm many of the dust trail predictions for the coming years.  They do
however predict the same time of maximum as the dust trail theory in 1999,
although the nature of this prediction is unknown to me.


Conclusion.

Leonid storms are predictable from dust trail calculations based on the
orbit of the parent comet 55P/Tempel-Tuttle.  The ZHR predictions are
limited by the lack of storm ZHR data, but the dust trail density model
of McNaught and Asher (1999) is very consistent with data available.


Asher, D.J. (1999) "The Leonid meteor storms of 1833 and 1966.",
   MNRAS, 307, 919-924

Brown, P. (1999) "The Leonid meteor shower: historical visual observations.",
   Icarus, 138, 287-308

Cooke, W. (1997) "Estimation of Meteoroid Flux for the Upcoming Leonid
   Stroms.",  http://see.msfc.nasa.gov/see/mod/leonids.html

Ferrin, I. (1999) "Meteor storm forcasting: Leonids 1999-2001.",
   Astron. Astrophys., 348, 295-299

Kondrat'eva, E.D. & Reznikov, E.A. (1985), "Comet Tempel-Tuttle and the
   Leonid meteor swarm.", Solar System Research, 199, 96-100

Kondrat'eva, E.D., Murav'eva, I.N. and Reznikov, E.A. (1997) "On the
   forthcoming return of the Leonid meteoric swarm.",
   Solar System Research, 31, 489-492

Lyytinen, E. (1999) "Leonid Predictions for the Years 1999-2007 with the
   Satellite Model of Comets.", Meta Research Bulletin, 31, 489-492

McNaught, R.H. (1999) "On predicting the time of Leonid storms.",
   The Astronomer, 35, 279-283

McNaught, R.H. & Asher, D.J. (1999a) "Leonid dust trails and meteor storms.",
   WGN, 27, 85-102

McNaught, R.H. & Asher, D.J. (1999b) "Variation of Leonid maximum times
   with location of observer.", Meteorit. Planet. Sci. (in press)

Wu, Z. and Williams, I. P. (1996) "Leonid meteor storms",
   MNRAS, 280, 1210-1218

Yeomans, D.K. (1981) "Comet Tempel-Tuttle and the Leonid meteors",
   Icarus, 47, 492-499
~

If you are interested in Radio Meteor reception, check:

     http://sapp.telepac.pt/coaa/r_meteor.htm

The program implements the dopplergram method of radio meteor detection that
was described in the Feb 99 issue of WGN.  Apart from a comms receiver, no
external hardware is required for this method.  The receiver audio signal is
connected into the sound port of a PC and the signal analysed for
doppler-shifted scattered signals which are displayed on the screen.

If you are expecting cloud for the 17th, this may be your alternative to
watch the show!

Regards

Bev
                            Bev and Jan Ewen-Smith
COAA, sítio do Poio, Mexilhoeira Grande 8500-149, Portugal
    Tel 00 351 282 471180        Fax 00 351 282 471516
><>        coaa@...        www.ip.pt/coaa       ><>

Dear Sir,
Some beautiful pictures of 1998 Leonids took by Hong Kong amateurs are
posted at the web page of Hong Kong Space Museum :

http://www.usd.gov.hk/hkspm/e_index.html

Please have a look.

Mr. Chu-lok CHAN
Member of Hong Kong Asronomical Society

The November issue of NAMN Notes, the newsletter of the North American
Meteor Network, is now available online at the NAMN website:

    http://web.infoave.net/~meteorobs

Among the topics discussed are the upcoming Leonids, as well as other
showers active during the month.

Clear skies!

Mark Davis, MeteorObs@...
Mt. Pleasant, South Carolina, USA
Coordinator, North American Meteor Network

Mr. J.M Trigo Rodriguez, stop !!

You don't belong to any University Department!!
Don't lie to our friends
Thanks

______________________________________________________