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(meteorobs) IMO Shower Circular - Geminids 1999
Doh! Still behind getting my meteor data in for the year... :(
Lew Gramer (the missing GRALE)
------- Forwarded Message
Date: Mon, 20 Dec 1999 05:54:43 -0500
From: Mark Davis <MeteorObs@charlestondot net>
Subject: IMO Shower Circular - Geminids 1999
To: [NAMN list]
-------------------------------------
I M O S h o w e r C i r c u l a r
-------------------------------------
GEMINID Activity 1999
=====================
Only 4 weeks after the fascinating Leonid meteor storm many observers
worldwide used the opportunity to record the maximum of the Geminids.
This shower is known for high rates lasting for several hours. Below
is a first overview of ZHRs calculated from reports received by the
IMO's Visual Commission until December 17, 1999. The rates are based
on reports of the following observers:
Jure Atanackov, Slovenia Mike Linnolt, USA
Juan A. Aveledo, Cuba Vladimir Lukic, USA
Neil Bone, UK Robert Lunsford, USA
Amol N. Chitale, India Francisco Munhoz, Cuba
Ian W. Cooper, New Zealand Sven Nather, Germany
Tim Cooper, South Africa Prakash Nitsure, India
Asdai Diaz Rodriguez, Cuba Alexei Pace, Malta
Frank Enzlein, Germany Arvind Paranjpye, India
Yuwei Fan, P.R. China Trevor Pendleton, UK
Sandy Ferguson, Canada Tushar Purohit, India
Mildred Formosa, Malta Rui Qi, P.R. China
Kai Gaarder, Norway Jurgen Rendtel, Germany
Martin Galea, Malta Mileny Roche Lamas, Cuba
Petros Georgopoulos, Greece Francisco A. Rodriguez, Spain
George Gliba, USA Wade A. Selvig, Canada
Roberto Gorelli, Italy Miguel A. Serra, Spain
Michal Haltruf, Czech Rep. Umberto Mule Stagno, Malta
Sun Hao, P.R. China Mike Stephens, Canada
Takema Hashimoto, Japan Chensheng Sun, P.R. China
Roberto Haver, Italy Tony Tanti, Malta
Kamil Hornoch, Czech Rep. Gabriela Triglav, Slovenia
Richard Huziak, Canada Mihaela Triglav, Slovenia
Rahul Jani, India Di Wang, P.R. China
He Jingyang, P.R. China Xiandong Yin, P.R. China
Albert Kong, UK Kim Youmans, USA
Wen Kou, P.R. China Ilkka Yrjola, Finland
Andrew Krochko, Canada Joseph Zammit, Malta
Robert Leyland, USA
Adrian Leylen, Cuba
Dong Li, P.R. China
All ZHRs were calculated with a constant population index of r=2.6
and a zenith coefficient of gamma=1.0. We find the known activity
"plateau" between December 14, 01h UT until about 18h UT with ZHRs
of the order of 100 or above. The highest ZHRs occurred between
13 and 18h UT (at 262.20 deg solar longitude).
Previous analyses of magnitude data yielded a value of r<2.6
(approximately 2.2) especially towards the end of the mentioned
plateau. Hence some of the ZHRs, derived from observations under
poor skies will be overestimated in this preliminary summary.
This also contributes to the large scatter of the averages.
The list gives averages of all available intervals and the standard
deviation. Time and solar longitude refer to the middle of the
averaged intervals, #Int is the number of intervals averaged.
Date Time Sol # ZHR +-
1999 UT (2000.0) Int
Dec 13 00.0h 260.542 2 27 5
02.0 .608 4 45 10
04.5 .714 7 37 8
11.5 261.011 2 39 12
14.5 .138 3 48 11
17.5 .265 5 65 16
21.0 .434 10 78 25
23.0 .520 17 72 20
Dec 14 00.5 .562 11 86 27
01.5 .604 11 106 23
02.5 .646 8 95 22
03.5 .689 8 95 24
04.5 .731 8 90 25
05.5 .774 10 90 24
06.5 .816 10 110 30
07.5 .859 9 105 40
08.5 .901 7 100 30
09.5 .943 8 105 35
10.5 .985 6 95 15
12.0 262.049 4 98 6
14.0 .134 8 135 20
16.0 .219 15 133 30
18.0 .304 24 120 40
20.5 .409 19 100 25
23.0 .515 5 69 34
Dec 15 01.0 .600 5 60 9
03.0 .685 3 60 15
05.0 .769 2 44 5
07.0 .854 2 24 7
We thank all observers who submitted their data promptly.
A detailed analysis will be prepared for a future issue of the
IMO Journal WGN. Of course, we are grateful for all further reports.
Juergen Rendtel
IMO President
December 19, 1999
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