Aktivität - Activity
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Graph of the Leonid ZHR drwan according to the immediate
data submitted by observers (Marc Gyssens, IMO). Leoniden-ZHR aus den unmittelbar während der Beobachtungen eingehenden Daten, erstellt von Marc Gyssens (IMO). |
L e o n i d e n 1 9 9 9 |
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Contents: Summary of first results Report from one of the AKM Leonid expeditions Photos of our observing site |
Inhalt: Erste Ergebnisse Bericht von einer der ALEX 99 Fotos vom Beobachtungsplatz |
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Graph of the Leonid ZHR drwan according to the immediate
data submitted by observers (Marc Gyssens, IMO). Leoniden-ZHR aus den unmittelbar während der Beobachtungen eingehenden Daten, erstellt von Marc Gyssens (IMO). |
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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 1999
====================
UPDATE
====================
New ZHR calculations have been made. On the one hand, newly
received observations have been included, and, on the other hand,
data based on estimated counts have been replaced by data based
on actual counts.
Visual observations of the 1999 Leonids revealed a distinctive
peak with a ZHR of about 5000 on November 18, 2h04m +/-5m UT
(solar longitude 235.286 +/- 0.004, eq. 2000.0). Ten minutes
earlier, at 1h53m +/- 5m UT (solar longitude 235.278 +/- 0.004,
eq. 2000.0), the ZHR profile shows a secondary peak with of ZHR of
about 3500. This secondary peak does not only occur in the combined
ZHR profile below, but also in the ZHR profile of several
individual observers, and is therefore probably real.
Apart from this secondary peak, the ZHR profile looks remarkably
smooth, even at the level of 5-minute intervals.
ZHR levels were above 1000 from roughly 1h20m UT to 2h45m UT
corresponding to 235.26 to 235.31 degrees in solar longitude.
All observers who were able to view the peak under good sky
conditions reported an abundance of faint meteors and a relative
absence of fireballs. Some observers noticed a drop in the
population index (i.e., a larger fraction of brighter meteors)
after the peak.
Reports from Mohammad Odeh (Jordanian Astronomical Society),
Casper ter Kuile (Dutch Meteor Society, observing near
Valencia, Spain), and Ilan Manulis (Israel) are very consistent
with the picture sketched above.
In addition, radio data from K. Maegawa (Toyokawa Meteor Observatory,
Aichi, Japan) reported by Kazuhiro Suzuki and the backscatter
radar data from Ondrejov Observatory (Czech Republic) reported by
Petr Pridal and Rosta Stork yield a peak time between 2h00m UT
and 2h10m UT.
It seems that the peak time of 2h08m UT predicted by Asher/McNaught
is confirmed within a margin of at most a few minutes, although the
observed activity is significantly higher. It is reasonable to
conclude that the peak activity has been caused by the 3-revolutions
old dust trail of 55P/Tempel-Tuttle.
The following observers (with their observing sites, not their
nationality or country of residence) have contributed data immediately
after the event, from which the ZHR profile given below
has been derived:
Rainer Arlt (Spain), Felix Betonvil (Canary Islands), C.L. Chan
(China), Mark Davis (USA), Asdai Diaz (Cuba), Yuwei Fan (China),
Fei Gao (China), Lew Gramer (USA), Rafael Haag (Brazil),
Dave Hostetter (USA), Andre Knoefel (Spain), Detlef Koschny (Spain),
Wen Kou (China), Alastair McBeath (UK), Alfredo Pereira (Portugal),
Josep Ma. Trigo-Rodriguez (Spain), Helena Valero-Rodriguez (Spain),
Renke Song (China), Wanfang Song (China), Jan Verbert (France),
Catarina Vitorino (Portugal), Jean-Marc Wislez (France), Mariusz
Wisniewski (Poland), Dan Xia (China), Dongyan Zha (China),
Jinghui Zhang (China), Yan Zhang (China), Jin Zhu (China).
(For groups of observers, only the name of the contributing
observers have been mentioned.)
Date Period (UT) Time (UT) Sol. Long. ZHR +/-
-----------------------------------------------------------
Nov 17 0600-1000 0800 234.527 16 2
Nov 17 1600-2010 1805 234.951 30 5
Nov 17 1900-2200 2030 235.052 53 14
Nov 17 2300-2400 2330 235.178 82 6
Nov 18 0000-0050 0026 235.217 210 60
Nov 18 0030-0100 0048 235.233 370 80
Nov 18 0050-0130 0110 235.248 560 90
Nov 18 0115-0145 0132 235.263 1160 180
Nov 18 0139-0155 0148 235.275 2360 600
Nov 18 0145-0200 0153 235.278 3430 750
Nov 18 0154-0205 0158 235.282 2820 550
Nov 18 0159-0209 0204 235.286 5400 880
Nov 18 0200-0215 0209 235.289 3540 580
Nov 18 0212-0233 0222 235.298 2110 580
Nov 18 0223-0247 0238 235.310 1140 280
Nov 18 0244-0320 0257 235.323 690 150
Nov 18 0315-0400 0340 235.353 240 60
Nov 18 0347-0505 0423 235.383 153 59
Nov 18 0512-0712 0557 235.449 61 12
Nov 18 0700-1100 0905 235.581 44 5
ZHRs are computed with a population index of 2.0, zenithal
exponent of 1.0.
---
Marc Gyssens, 1999 November 18, 7h UT.
wgn@imo.net
---
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Vor dem Abflug nach Spanien am 17. November auf dem Flughafen
Berlin-Tegel: Bob, Pierre, Manuela, Cathy, Sirko. Before boarding to Spain at Berlin-Tegel airport - midday Nov. 17. |
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Für 2 Nächte war dieses Gebäude unser Quartier
in Südspanien. This casa was our observational base for 2 nights in southern Spain. |
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Windschutz war gefragt, denn zum Meteorsturm gab es auch
einen heftigen Wind. Cathy nutzte eines der Mietautos. Wind protection was necessary - the meteor storm was accompanied by gusty winds. |
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