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Perseids 2004
Results of the IMO Video Meteor Network - August 2004
by Sirko Molau (Internationa Meteor Organisation)


Since what we have seen so far in 2004 was not so impressive, it's no wonder that August outbeated the previous months by far. Firstly, the number of observers and operated video cameras increased (the summer break of Ilkka Yrjola is over and we also received Perseid observations from Ondrejov observatory again). Secondly, nights were getting longer again, and finally the average number of meteors per hour increased by a factor of three compared to the first half of the year. Last but not least, there has been a new and very effective camera named AVIS2 in operation.

After the image intensifer of my old camera AVIS reach the end of lifetime earlier this year (after all, the second hand tube yielded about 5,000 hours of observing time in his "second life" and secured more than 26,000 meteors), I was looking for an replacement tube. At EBAY, there are regularly offers of identical tubes at reasonable rates, but most of them are sold in the US and cannot be exported. After some time I got a used Philips XX1332 for about Euro 200 from an UK dealer (www.abex.com). That's a second generation tube with a large photo cathode of 50 mm diameter. After I adapted my camera, AVIS2 saw first light during the Perseid campaign. At first I noticed, that contrary to other MCPs this tube shows some vignetting, which was not caused by the small format camera lens. Then I realized, that using the same objective lens the size of the fov had doubled, whereas the gain was at least as good as that of the old tube. In result, I achieved a 95 degree field of view with a remarkable limiting magnitude of 6 mag with my 35 mm f/2.0 lens. It came as no surprise, that the number of meteor records was correspondingly great. In fact, it was for the first time that my camera recorded in the same time interval more meteors than me!

All in all, I can only recommend this tube. Of course, image-intensified cameras are more expensive, less robust and have a shorter life time. However, their efficiency is still unbeated, especially away from larger showers.

Beside the surprising results of AVIS2 there was also some misfortune in August: When I was at the AKM Perseid camp in Ketzuer, MINCAM1 was operated automatically at my home. However, Murphy was active and let the camera fail for unknown reason just in the days around the Perseid maximum.

What about the observing results? Esko Lyytinen, who became well-known by his precise Leonid predictions, had forcasted enhanced Perseid activity for August 11, around 23 UT, caused by the one-revolution dust trail. Thus, the observers were especially alerted and fortunately the weather was cooperative at many sites. Visual observations in Europe yielded high Perseid activity in the first hours of the night, which reduced later somewhat but increased again towards the morning. Taking the low radiant at observation start into consideration it was immediately clear, that the activity early in the night was higher than usual. This was clearly confirmed by first analyses of visual observations. Some video observers, however, reported no enhanced activity at first. Later it became clear, that they had simply forgotten to correct for the low radiant altitude.

I created a graph (http://www.molau.de/temp/per04.gif) of all video observations available to me, which were not affected by clouds (except for AVIS2, where at some time a small cloud correction was applied), and which covered the early maximum. In addition to the data of the IMO network, I included an observation by Enrico Stomeo of Italy, who had inspected his video observation manually. Meteor counts were binned in 5 min intervals and corrected for the radiant altitude. Since the individual data sets are statistically independent of each other, all graphs were finally added. The resulting activity curve made of more than 500 Perseids shows fewer random fluctuations and a clear maximum.

The more meteors each camera recorded, the better the early peak becomes visible. In the overall activity graph maximum activity occurs in the 21:05-21:10 UT interval. It stands clearly out of the background, i.e. (almost) all cameras recorded more meteors in that time interval than before or after. Interestingly, there is a difference of almost 10 minutes to the visual observations, whose activity graph made of 30 times more meteors peaked at 20:56 UT.

1. Observers
============

Code    Name        Place           Camera         FOV    LM Nights Time Meteors
--------------------------------------------------------------------------------
EVAST Evans       Moreton       RF1 (1.2/12)      20 dg  4 mag  11   71.6 h  447
KACJA Kac         Kostanjevec   METKA (0.8/8)     55 dg  4 mag  16   95.6 h  426
KOSDE Koschny     Noordwijkerh. ICC3 (0.85/25)    25 dg  6 mag   6   33.3 h  359
                                ICC2 (0.85/25)    25 dg  6 mag   1    3.0 h   44
MOLSI Molau       Seysdorf      AKM1 (0.85/25)    32 dg  6 mag  11   53.4 h  238
                                MINCAM1 (1.4/12)  35 dg  4 mag  22  121.1 h  266
                  Ketzuer       AVIS2 (2.0/35)    95 dg  6 mag   9   39.4 h  927
SLAST Slavec      Ljubljana     KAYAK1 (1.8/28)   50 dg  4 mag  16   81.9 h  487
STORO Stork       Ondrejov      OND1 (2.4/35)     70 dg  3 mag   3   18.4 h  123
STRJO Strunk      Leopoldshoehe MINCAM2 (0.8/8)   42 dg  4 mag  24   98.5 h  498
                                MINCAM3 (0.8/6)   55 dg  3 mag  12   70.3 h  443
UEBST Ueberschaer Aachen        MIMO (0.95/25)    13 dg  4 mag   6   29.7 h   84
YRJIL Yrjola      Kuusankoski   FINEXCAM (0.8/6)  50 dg  3 mag  13   51.9 h  404
--------------------------------------------------------------------------------
Sum                                                             30  768.1 h 4746



2. Observing Times (h)
======================

Aug    01   02   03   04   05   06   07   08   09   10   11   12   13   14   15
--------------------------------------------------------------------------------
EVAST  5.0   -    -   5.4   -   5.9  5.8   -    -    -    -   6.0   -   6.4   -
KACJA   -    -    -   6.1  6.1   -    -    -   6.3  7.1  7.5  3.0  0.6  4.1  7.3
KOSDE   -   5.0   -   5.6   -    -    -   5.0  4.3   -   7.6   -    -    -    - 
        -    -    -    -    -    -    -    -    -    -   3.0   -    -    -    -
MOLSI   -    -   4.6  4.5  6.6  4.4  5.2  6.7   -    -    -    -    -    -    - 
       2.2   -   7.4  6.5  7.4  3.5  7.5  7.6   -   3.7   -    -    -    -   8.0
        -    -    -    -    -    -    -    -   3.0  5.0  6.0  1.1   -   6.3  6.3
SLAST   -    -    -    -    -    -    -    -    -   3.5  6.8   -    -   3.5  4.6
STORO   -    -    -    -    -    -    -    -   5.8  6.2  6.4   -    -    -    -
STRJO  5.5  5.9  3.2  3.9  5.9  6.0  6.1  4.7  6.2   -   6.4  0.5  3.6  2.3  4.1
       5.4  5.5  5.8   -   5.9  6.5  5.9   -   6.0   -   6.1   -    -    -    -
UEBST   -    -    -    -   7.4   -    -    -   6.7  0.5  8.6  5.5   -    -    -
YRJIL   -    -    -    -    -    -    -    -    -   3.3  4.0  3.3  2.6  3.1  2.6
--------------------------------------------------------------------------------
Sum   18.1 16.4 21.0 32.0 39.3 26.3 30.5 24.0 38.3 29.3 62.4 19.4  6.8 25.7
32.9     

Aug    16   17   18   19   20   21   22   23   24   25   26   27   28   29  
30   31
-------------------------------------------------------------------------------------
EVAST   -    -    -   6.8   -    -    -    -    -    -    -   7.6   -   7.0 
7.9  7.8
KACJA  7.1  7.6  7.8   -    -    -    -   4.7   -    -    -   7.8  8.5  4.0  
-    -
KOSDE   -    -    -    -    -    -   5.8   -    -    -    -    -    -    -   
-    - 
        -    -    -    -    -    -    -    -    -    -    -    -    -    -   
-    -
MOLSI   -    -    -    -   0.4   -   6.0   -   5.3   -    -   7.6  2.1   -   
-    - 
       7.1  8.1  8.2   -   1.3  1.4  6.4  6.2  8.6  0.6   -   8.8  4.3  3.9  
-   2.4
        -   6.3  3.4  2.0   -         -    -    -    -    -    -    -    -   
-    -
SLAST  6.7  7.1  7.0  6.8   -    -   5.3  7.7  5.1  0.7   -   4.5  4.6  6.0 
2.0   -
STORO   -    -    -    -    -    -    -    -    -    -    -    -    -    -   
-    -
STRJO  0.7  0.5  0.7  6.9  1.0  7.0  7.0  3.5  0.5   -    -    -    -    -   
-   6.4
        -    -    -    -    -   6.1  7.2  3.1   -    -    -    -    -    -   
-   6.8
UEBST   -    -    -    -    -    -    -    -    -    -    -    -    -    -  
1.0   -
YRJIL   -   3.7  4.7   -    -   3.3  4.7  5.3  5.5   -    -    -    -   5.8  
-    -
-------------------------------------------------------------------------------------
Sum   21.6 33.3 31.8 22.5  2.7 17.8 42.4 30.5 25.0  1.3   -  36.3 19.5 26.7 10.9
23.4          



3. Results (Meteors)
====================

Aug    01   02   03   04   05   06   07   08   09   10   11   12   13   14   15
--------------------------------------------------------------------------------
EVAST  31    -    -   18    -   40   55    -    -    -    -  102    -   37    -
KACJA   -    -    -    8   15    -    -    -   42   41  155   11    2   18   24
KOSDE   -   44    -   37    -    -    -   51   58    -  139    -    -    -    -
        -    -    -    -    -    -    -    -    -    -   44    -    -    -    -
MOLSI   -    -    7   31   22   18   38   35    -    -    -    -    -    -    -
        5    -    5   22   23   12   18   30    -    6    -    -    -    -   19
        -    -    -    -    -    -    -    -   83  131  363   17    -  173   78
SLAST   -    -    -    -    -    -    -    -    -   27  131    -    -    7   43
STORO   -    -    -    -    -    -    -    -   36   25   62    -    -    -    -
STRJO  22   23   13   12   25   20   34   28   43    -  142    2   10    7   11
       14   24   15    -   33   26   27    -   45    -  181    -    -    -    -
UEBST   -    -    -    -    8    -    -    -   13    1   53    7    -    -    -
YRJIL   -    -    -    -    -    -    -    -    -   38  150   33   11   31   14
--------------------------------------------------------------------------------
Sum    72   91   40  128  126  116  172  144  320  269 1420  172   23  273 
189     

Aug    16   17   18   19   20   21   22   23   24   25   26   27   28   29  
30   31
-------------------------------------------------------------------------------------
EVAST   -    -    -   25    -    -    -    -    -    -    -   46    -   17  
29   47
KACJA  15   30   21    -    -    -    -   10    -    -    -   10   17    7   
-    -
KOSDE   -    -    -    -    -    -   30    -    -    -    -    -    -    -   
-    -
        -    -    -    -    -    -    -    -    -    -    -    -    -    -   
-    -
MOLSI   -    -    -    -    3    -   25    -   22    -    -   33    4    -   
-    -
       10   12   18    -    1    1    9   13   19    1    -   19    8   10   
-    5
        -   49   16   17    -    -    -    -    -    -    -    -    -    -   
-    -
SLAST  32   33   32   27    -    -   40   30   16    2    -   29   19   16   
3    -
STORO   -    -    -    -    -    -    -    -    -    -    -    -    -    -   
-    -
STRJO   3    2    3   19    5   25   20    9    2    -    -    -    -    -   
-   18
        -    -    -    -    -   28   25    6    -    -    -    -    -    -   
-   19
UEBST   -    -    -    -    -    -    -    -    -    -    -    -    -    -   
2    -
YRJIL   -   10   18    -    -   17   21   21   22    -    -    -    -   18   
-    -
-------------------------------------------------------------------------------------
Sum    60  136  108   88    9   71  170   89   81    3    -  137   48   68  
34   89    

************************************************************ 
*   Sirko Molau                 *                          *
*   Abenstalstr. 13b            *              __          *
*   D-84072 Seysdorf            *       " 2B v 2B "        *
*   Germany                     *                          * 
*   phone: +49-8752-869438      *             Shakespeare  *
*   email: sirko@molau.de       *                          *
*   www  : www.molau.de         *                          *
************************************************************

Grafico realizzato da Sirco Molau con tutte le osservazioni disponibili, considerate le correzioni per le altezze del radiante, e una curva sommatoria di piu' di 500 Perseidi, dalla quale appare evidente che il picco video di attivitą č avvenuto alle 2105-2110 UT, cioe' quasi 10 minuti dopo di quello registrato visualmente (cortesia Sirco Molau; il commento č di Enrico Stomeo, esponsabile UAI-sm).
Con una punta di giusto orgoglio, Stomeo fa notare che questa analisi di dati video raccoglie per la prima volta anche le osservazioni di alcuni osservatori italiani.


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Pagina caricata in rete: 24 settembre 2004; ultimo aggiornamento: 24 settembre 2004