(meteorobs) IMO Shower Circ.: 2004 Perseids

Wed Aug 18 06:06:10 EDT 2004

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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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   The 2004 Perseids, 4th analysis

A total of 16536 Perseids is now comprised by 
1567 individual observing periods as used for
the analysis given below. A short-lived peak
of activity was observed at 20h56m UT +-4 min
on August 11, 2004. The precise moment was
derived from various samplings of the data
into averages, so it is not directly visible
in the activity table below.

The time predicted by Esko Lyytinen was 20h54m,
and it cannot be excluded that observers' pre-
judice has 'helped' match this forecast. The
study of meteor timings on video recordings
may clarify this. Any difference is most likely
below 10 minutes though.

If we assume a background activity of 80-90 during
the peak, we can derive the full width at half
maximum (FWHM) to be about 55 minutes (20h25m -
21h20m).

Enhanced Perseid ZHRs were observed during the
entire nights Aug 11/12 and 12/13. This is also
in line with Esko's comment that "because Jupiter
lowers the ecliptic crossing radii in general 
this year, there may be enhanced general activity
as well."

-------------------------------------------------------
Date (UT)   Time  Solarlong   nINT   nPER    ZHR
-------------------------------------------------------
Aug 9.2490  05:59   136.928      6     36     27  +-  4
Aug 11.054  01:18   138.659     20    228     34  +-  2
Aug 11.404  09:42   138.995     19    236     41  +-  3
Aug 11.726  17:25   139.304     26    193     68  +-  5
Aug 11.788  18:55   139.364     36    159     63  +-  5
Aug 11.824  19:47   139.398     45    240     85  +-  5
Aug 11.844  20:15   139.418     38    281    106  +-  6
Aug 11.852  20:27   139.425     34    274    161  +- 10
Aug 11.862  20:41   139.435     54    486    174  +-  8
Aug 11.865  20:46   139.438     51    412    176  +-  9
Aug 11.871  20:54   139.444     54    437    187  +-  9
Aug 11.877  21:03   139.449     72    665    185  +-  7
Aug 11.884  21:13   139.456     64    431    147  +-  7
Aug 11.891  21:23   139.463     66    490    134  +-  6
Aug 11.899  21:35   139.470     72    574    119  +-  5
Aug 11.909  21:49   139.480    104    581     94  +-  4
Aug 11.927  22:15   139.497     91    724     99  +-  4
Aug 11.949  22:47   139.518     87    640     82  +-  3
Aug 11.969  23:15   139.538     80    759     93  +-  3
Aug 11.991  23:47   139.559     59    690    105  +-  4
Aug 12.012  00:17   139.579     52    656    109  +-  4
Aug 12.032  00:46   139.598     59    763    125  +-  5
Aug 12.052  01:15   139.617     65    904    134  +-  4
Aug 12.073  01:45   139.637     46    671    127  +-  5
Aug 12.099  02:23   139.662     31    524    148  +-  6
Aug 12.163  03:55   139.724     37    465     98  +-  5
Aug 12.249  05:59   139.806     19    366     89  +-  5
Aug 12.319  07:39   139.874     29   1066    102  +-  3
Aug 12.390  09:22   139.942     14    562    118  +-  5
Aug 12.510  12:14   140.057     20    241    101  +-  6
Aug 12.726  17:25   140.264     21    294    110  +-  6
Aug 12.836  20:04   140.370     21    212     90  +-  6
Aug 12.876  21:01   140.408     20    344     84  +-  5
Aug 12.943  22:38   140.473     22    491     72  +-  3
Aug 13.120  02:53   140.643     15    230     47  +-  3
Aug 14.015  00:22   141.503     11    156     30  +-  2
Aug 15.417  10:00   142.850      7     55     10  +-  1
-------------------------------------------------------
r = 2.0; solar longitudes refer to J2000.0

If you have not yet submitted your observing report,
it is still worth doing so as a final analysis will
be done in early September.

If you have submitted preliminary data, please send 
your final report also very soon. Note that a break-
down into small observing periods (5-min around the
peak) is appreciated. Magnitude distributions of 
the Perseids should also be broken down into small 
periods, because short-lived features in the mass
distribution of Perseid particles may be detected.

The current activity profile is based on the data
by the following observers, to whom we are most
grateful:

Maxim Andreev (Russia)
Rainer Arlt (Germany)
Joseph D. Assmus (USA)
Morteza Azizi (Iran)
Roberto Bacci (Italy)
Lukas Bolz (Germany)
Michael Boschat (Canada)
Dustin Brown (USA)
Andreas Buchmann (Switzerland)
Jens Th. Carlsen (Denmark)
Gu Chan (China)
Danijela Cuic (Serbia)
Zolfaqar Daneshi (Iran)
Luigi D'Argliano (Italy)
Sietse Dijkstra (the Netherlands)
Dariusz Dorosz (Poland)
Audrius Dubietis (Lithuania)
Garry Dymond (Canada)
Shlomi Eini (Israel)
Frank Enzlein (Germany)
Li Feng (China)
Marek Fretala (Poland)
Martin Galea de Giovanni (Malta)
George W. Gliba (USA)
Roberto Gorelli (Italy)
Daniel Grun (Germany)
Laszlo Gyarmati (Hungary)
Amir Hasanzadeh (Iran)
Takema Hashimoto (Japan)
Jan Hattenbach (Germany)
Roberto Haver (Italy)
Davood Hemati (Iran)
Veli-Pekka Hentunen (Finland)
Zoltan Hevesi (Hungary)
Kamil Hornoch (Czech Republic)
Yandong Hu (China)
Kaca Jankovic (Serbia)
Carl Johannink (the Netherlands)
Wojciech Jonderko (Poland)
Paul Jones (USA)
Piotr Kedzierski (Poland)
Roy Keeris (the Netherlands)
Soheil Khoshbinfar (Iran)
Andre Knofel (Germany)
Lukasz Kowalski (Poland)
Dovile Kraulaidiene (Lithuania)
Ralf Kuschnik (Germany)
Dominika Lacheta (Poland)
Marco Langbroek (the Netherlands)
Anna Lemiecha (Poland)
Peter van Leuteren (the Netherlands)
Anna Levina (Israel)
Mike Linnolt (USA)
Shangfei Liu (China)
Robert Lunsford (USA)
Vladimir Lukic (USA)
Hartwig Luthen (Germany)
Christophe Marlot (France)
Pierre Martin (Canada)
Antonio Martinez (Venezuela)
Felix A. Martinez (USA)
Mikhail Maslov (Russia)
Bert G. Matous (USA)
Alastair McBeath (UK)
Bruce McCurdy (Canada)
Huan Meng (China)
Koen Miskotte (the Netherlands)
Sirko Molau (Germany)
Robert Morgan (USA)
Thom Morgan (USA)
Norman W. McLeod (USA)
Arash Nabizadeh Haghighi (Iran)
Sven Nather (Germany)
Arkadiusz Olech (Poland)
Daniel van Os (the Netherlands)
Anna Palasz (Poland)
Bruce Patterson (Canada)
Cedric Peinado (France)
Karolina Pyrek (Poland)
Hamid Rakooy (Iran)
Jose Afonso dos Reis Martins (Portugal)
Jurgen Rendtel (Germany)
Petra Rendtel (Germany)
Antonio Sasanski (Macedonia)
Branislav Savic (Serbia)
Maziar Seyed-Nezhad (Iran)
Andrzej Skoczewski (Poland)
Izabela Spaleniak (Poland)
David Stine (USA)
Enrico Stomeo (Italy)
Wesley Stone (USA)
Boris Stromar (Croatia)
Cristina Tinta-Vass (Romania)
Marko Toivonen (Finland)
Shigeo Uchiyama (Japan)
Michel Vandeputte (Belgium)
Wei Wang (China)
William W. Watson (USA)
Oliver Wusk (Germany)
Jiaqing Yang (China)
Joseph Zammit (Malta)
Ewa Zegler (Poland)
Xu Zhang (China)
Hao Zheng (China)
Wen Zhou (China)
Jurga Zieniute (Lithuania)
Vladimir Znojil (Czech Republic)

The input is still going on; it is possible that
your name will appear in a later phase of analysis.

Rainer Arlt, 2004 August 18, 10h UT
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