Results of the IMO Video Meteor Network - August 2004
=====================================================
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 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
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EVAST Evans Moreton RF1 (1.2/12) 20 dg 4 mag 11 71.6 h 447
KACJA Kac Kostanjevec METKA (0.8/8) 42 dg 2 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
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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
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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
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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
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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 - -
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Sum 60 136 108 88 9 71 170 89 81 3 - 137 48 68 34 89
Sirko Molau, 2004/09/15