From: Marc Gyssens, International Meteor Organization 
Date: Sat, 18 Nov 2000 12:38:39 +0000 (WET)

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

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               LEONID Activity 2000
               --  final update  --
    Update on Nov 17/18 (American observations)
         Preliminary results of Nov 18/19
               --------------------

A word of thanks
----------------
First, I want to emphasize that this is the last update you
receive in connection with the IMO's 2000 Leonids Rapid
Communication Network. I wish to thank all observers who
made this endeavor possible. Most of them are acknowledged
below, but some may have been forgotten in the heat of the
battle against time to get these releases out as soon as
possible. Other observers sent their first reports too late
to be included, but also their efforts are appreciated. Now
that the general picture of the profile of the 2000 Leonid
Meteor Shower has been exhibited, the goal of this Network
has been achieved. Expect to see a more comprehensive first
analysis of the 2000 Leonid Meteor Shower in the December
issue of WGN, the Bimonthly Journal of the International
Meteor Organization. For that purpose, please send your full
observing reports as soon as possible to the IMO's Visual
Commission Director, Rainer Arlt. As this is the last release,
there is no need anymore to send "quick reports" to me!

Update
------
Since the last release, a few American observations
pertaining to Nov 17/18 have been added, as well as the
(few) observations we received pertaining to Nov 18/19.  The
former do not change the picture sketched in our previous
release; the latter show the activity slowly fading away,
without any obvious unusual features.

With regard to the Nov 17/18 observations, the additional
data tend to lower some ZHRs slightly (the value for the Nov
18, 7h15m +/- 15m peak being lowered from about 450 to about
420, for example), but do not at all change the general
picture.

With regard to the scarce Nov 18/19 observations available
yet, neither Japanese, nor European, nor American data
indicate anything unusual. By Nov 18, 10h UT, Leonid ZHRs
reached the level before the rise to the Nov 18, 3h45m peak
again. Since then, they continued to drop to a level of 10
+/- 5 by Nov 19, 9h UT. It must be noted that not too much
importance should be attached at this point to the plateau
in the activity profile suggested by the table below between
Nov 18, 11h UT and Nov 19, 2h UT. As they are computed from
data from few different observers, the perception of an
individual observer can greatly influence the final result.

Despite a large scatter among individual observers' ZHR
values - not only because of differences in perception, but
also because of the disturbing Last Quarter Moon, the
influence of which on observations goes beyond what can be
taken into account by a reduction based on the stellar
limiting magnitude - the totality of the observations
exhibit a clear pattern explained in this and previous
releases. Because of the larger scatter, however, great care
remains necessary in further interpreting the observations!

The following observers have contributed data immediately
after the event, from which the ZHR profile given below
has been derived:

Birger Andresen, Rainer Arlt, Adrian Arquiola, Joseph
Assmus, Jure Atanackov, Felix Bettonvil, Neha Bhandari,
Lukasz Bielun, Lukas Bolz, Neil Bone, Michael Boschat,
Andreas Buchmann, Bill Burton, Christian Castillo, Asdai
Diaz, Susan Delaney, Marc de Lignie, Michael Doyle, Frank
Enzlein, Yuwei Fan, Magdalena Gawla, Petros Georgopoulos,
Roberto Gorelli, Lew Gramer, Robin Gray, Rosely Gregio,
Valentin Grigore, Rafael Haag, Wayne Hally, Roberto Haver,
Zoltan Hevesi, Ken Hodonsky,Ken Hodonsky, David Holman,
Tamas Hubay, Brigitte Humphries, Emmanuel Jehin, Kevin
Jones, Tomsilav Jurkic, Javor Kac, Primoz Kajdic, Akos
Kereszturi, Albert Kong, Wen Kou, John Krempasky, Vineet
Kulkarni, Zsolt Lantos, Ken Legal, Harry J. Lehto, Robert
Leyland, Mike Linnolt, Jerry Lodriguss, Hartwig Luethen,
Robert Lunsford, Pierre Martin, Jose A.R. Martins,
S. Maticic, Alastair McBeath, Norman W. McLeod III, Frank
J. Melillo, Huan Meng, H. Mikuz, Sirko Molau, Kiyohide
Nakamura, Piotr Nawalkowski, Michael Nezel, Eran Offek,
Dragana Okolic, Arkadiusz Olech, Kazuhiro Osada, Alexei
Pace, Arvid Parnajpye, Natasa Petelin, Ulhas Pradhan,
Szaniszlo Prohaszka, Mayuresh Prabhune, Nilesh
V. Puntambekar, Tushar Purohit, Janne Pyykkoe, Guo-ming Qin,
Francisco A. Rodriguez Ramirez, Gaurav Rathode, Gilberto
Klar Renner, Kulkarni Rhishikesh, Elaina Runge, Karl Runge,
Manuel S. Ruiz, Victor R. Ruiz, Carlos Saraiva, Hideko Sato,
Mikiya Sato, Tomoko Sato, Miguel A. Serra, Eini Shlomi,
Brian Shulist, Yuying Song, Bjoern Soerheim, Konrad Szaruga,
Richard Taibi, Kazumi Terakubo, Sanjay Thorat, Mihaela
Triglav, Josep Trigo, Arnold Tukkers, Varada Vaidya, Erwin
van Ballegoij, Vishnu Vardhan, George Varros, Cis Verbeeck,
Jean-Marc Wislez, Anna Witas, Jonderko Wojciech, Oliver
Wusk, Dan Xia, Karen Young, Ju Zhao, Jing Zhong, Jin Zhu,
Xiaojin Zhu, Kamil Zloczewski.

Mark Davis was instrumental in forwarding observations sent
to the Meteorobs mailing list.

Date   Time (UT)  Sol. long. Intervals Leonids   ZHR   +-
                  (2000.0)
---------------------------------------------------------
Nov 15  22h05m     243.848       2         11     13    4

Nov 16  03h33m     234.067       1          7      8    3
Nov 16  21h16m     234.820       6         44     20    3

Nov 17   3h02m     235.062       9         50     33    4
Nov 17   4h53m     235.141      10         74     47    5
Nov 17   6h00m     235.187       3         30    108   20
Nov 17   6h16m     235.198       3         16     66   17
Nov 17   6h36m     235.212       4         22     57   12
Nov 17   7h59m     235.270      10        117    104   10
Nov 17   9h25m     235.330      10         64     44    5
Nov 17  15h00m     235.565       7         74     50    6
Nov 17  19h22m     235.750      14        237     69    5
Nov 17  23h01m     235.903       9        164    102    8

Nov 18  00h27m     235.963       7         62    101   13
Nov 18  01h14m     235.995      15        170    161   12
Nov 18  01h47m     236.018      13        264    219   14
Nov 18  02h17m     236.040      25        496    211   10
Nov 18  02h45m     236.059      24        518    232   10
Nov 18  03h17m     236.082      31        668    236    9
Nov 18  03h46m     236.101      45        809    296   10
Nov 18  04h14m     236.121      41        827    247    9
Nov 18  04h45m     236.143      21        274    218   13
Nov 18  05h13m     236.163      17        454    225   11
Nov 18  05h44m     236.184      13        418    301   15
Nov 18  06h23m     236.212      17        401    286   14
Nov 18  07h12m     236.246      11        573    424   20
Nov 18  07h46m     236.270      20        500    354   16
Nov 18  08h16m     236.290      24        689    237    9
Nov 18  08h43m     236.310      17        229    148   10
Nov 18  09h18m     236.335      17        322     84    3
Nov 18  11h08m     236.411      13        169     41    3
Nov 18  18h06m     236.704      15        165     40    3

Nov 19  02h11m     237.044      11         52     36    5
Nov 19  08h37m     237.314       3          6     12    5
---------------------------------------------------------

ZHRs are computed with a population index of 2.0, zenithal
exponent of 1.0.