Results of the IMO Video Meteor Network - April 2008
====================================================
With nearly 1500 hours of effective observing time and more than 3000 meteors,
April 2008 could not keep up with the record-breaking April before. However,
there were major differences between the individual observing sites. Once
more, Carl Hergenrother was on top of the list - he missed only a single
night at his Arizona observing site. Observers in northern and western
Germany managed to collect twenty and more observing nights as well, but
farther south the weather was only mediocre.
"Highlight" of the month with respect to meteors were once more the Lyrids.
Their maximum, however, coincided with full moon, so that no spectacular
display was to be expected. This is also reflected by the meteor number, which
was only slightly higher on April 22 than on other nights. Overall, the
activity remained low with an average of two meteor records per hours.
If nothing happens in the sky, then it is time to put some effort into the
data analysis. Together with Pete Gural, I analyzed the sporadic meteors in
the IMO Video Meteor Database with its nearly 330,000 records. The results
were presented a few days ago at the "Meteoroid and Meteor Observations as a
Basis for Models" conference in Huntsville, Alabama. Here I would like to
present a few facts and figures from our presentation.
During the analysis, meteors were first assigned to the known meteor showers
(based on the IMO Working List). For the remaining meteors it was checked,
whether they belong to one of the six known sporadic sources (Helion,
Antihelion, N/S Apex , N/S Toroidal - the base data of which were taken from
the work of Margaret Campbell-Brown), or whether they were "true" sporadics.
In the end it turned out, that about one quarter of all meteors are shower
meteors (most of all Perseids, Orionids and Geminds). Another 15% could be
assigned to the sporadic sources, and more than half of all meteors (60%) are
true sporadics. Among the sporadic sources, about half of the meteors belong
to the Antihelion source, and about one quarter to the N Apex source. The
remaining meteors are S Apex and N Toroidal meteors in equal frequency
(Figure 1, left). The strength of the northern sporadic branches can be
explained easily when considering that 95% of all meteors in the database
were recorded in the northern hemisphere. When the meteor frequencies are
corrected for the observing geometry it turnes out, that the northern and
southern branch of the Apex and Toroidal source are about equaly strong.
Figure 1: Relative frequency of the individual sporadic sources in the
IMO Video Meteor Database (left – uncorrected; right – corrected for
observing geometry)
Looking at the annual distribution of meteors (normalized to the overall
number of sporadic meteors in that particular solar longitude interval) we
see some variation in the activity profile of the N Apex source. Once more,
if the observing geometry (i.e. the observability of a particular source in
the course of the year) is accounted for, all sources show at the first
approximation a roughly constant activity, and also the percentage of the
sporadic sources among all sporadics varies only little.
It is more tricky to get an estimate of the absolute sporadic activity in
the course of the year, as the particular observing conditions of each
observation (limiting magnitude, size of field of view) are unknown. The
effective observing time per night is also not part of the positional
database PosDat. So we normalized the number of sporadics with the overall
effective observing time per month (in the hope that the observing conditions
are about the same when averaged over many years) and obtained a roughly
sinusoidal activity graph with a minimum of more than two sporadics per
hour in mid-March and a maximum of more than four sporadics per hour in
mid-September (Figure 2).
Figure 2: Annual variation of the average number of sporadic meteors
per hour (red – original values; yellow – Sine fit)
1. Observers
============
Code Name Place Camera FOV LM Nights Time Meteors
--------------------------------------------------------------------------------
BENOR Benitez-S. Las Palmas TIMES4 (1.4/50) 20 dg 3 mag 6 11.0 h 23
TIMES5 (0.95/50) 10 dg 3 mag 7 7.3 h 21
BRIBE Brinkmann Herne HERMINE (0.8/6) 55 dg 3 mag 24 76.0 h 167
CASFL Castellani Monte Baldo BMH1 (0.8/6) 55 dg 3 mag 13 62.7 h 107
BMH2 (0.8/6) 55 dg 3 mag 9 39.6 h 49
CRIST Crivello Valbrevenna STG38 (0.8/3.8) 80 dg 3 mag 3 14.6 h 29
GONRU Goncalves Tomar TEMPLAR1(0.8/3.8) 80 dg 3 mag 8 64.7 h 95
HERCA Hergenroth. Tucson SALSA (1.2/4) 80 dg 3 mag 29 221.4 h 305
HINWO Hinz Brannenburg AKM2 (0.85/25) 32 dg 6 mag 12 66.4 h 140
KACJA Kac Kostanjevec METKA (0.8/8) 42 dg 4 mag 15 71.4 h 131
Kamnik REZIKA (0.8/6) 55 dg 3 mag 7 36.2 h 35
Ljubljana ORION1 (0.8/8) 42 dg 4 mag 19 72.6 h 99
KOSDE Koschny Noordwijkerh. ICC4 (0.85/25) 25 dg 5 mag 10 46.3 h 76
LUNRO Lunsford Chula Vista BOCAM (1.4/50) 60 dg 6 mag 15 92.4 h 251
MOLSI Molau Seysdorf AVIS2 (1.4/50) 60 dg 6 mag 8 44.2 h 375
MINCAM1 (0.8/6) 55 dg 3 mag 15 48.4 h 74
Ketzuer REMO1 (0.8/3.8) 80 dg 3 mag 20 72.7 h 160
REMO2 (0.8/3.8) 80 dg 3 mag 12 47.4 h 163
PRZDA Przewozny Berlin ARMEFA (0.8/6) 55 dg 3 mag 3 18.0 h 51
ROBBI Roberto Verona FIAMENE (0.8/3.8) 80 dg 3 mag 12 44.9 h 81
SLAST Slavec Ljubljana KAYAK1 (1.8/28) 50 dg 4 mag 13 49.8 h 77
STOEN Stomeo Scorze MIN38 (0.8/3.8) 80 dg 3 mag 10 58.9 h 120
STORO Stork Kunzak KUN1 (1.4/50) 55 dg 6 mag 1 8.3 h 25
Ondrejov OND1 (1.4/50) 55 dg 6 mag 3 9.8 h 51
STRJO Strunk Herford MINCAM2 (0.8/6) 55 dg 3 mag 23 39.8 h 80
MINCAM3 (0.8/8) 42 dg 4 mag 9 20.5 h 50
MINCAM5 (0.8/6) 55 dg 3 mag 9 29.3 h 67
YRJIL Yrjola Kuusankoski FINEXCAM (0.8/6) 55 dg 3 mag 21 96.0 h 158
--------------------------------------------------------------------------------
Sum 30 1470.6 h 3060
2. Observing Times (h)
======================
Apr 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15
--------------------------------------------------------------------------------
BENOR - - - - - - 2.0 2.7 3.4 - - - - - -
- - - - - - 3.2 0.3 3.8 - - - - - -
BRIBE 0.3 - - - - 7.0 4.5 1.7 3.7 2.0 5.1 1.8 0.3 2.0 3.3
CASFL 0.5 - 9.3 6.2 3.1 - 2.0 - - 1.0 - - - - -
3.4 6.3 6.9 4.2 5.1 - 6.5 - - - - - - - -
CRIST - - - - 5.8 - - - - - - - - - -
GONRU 9.7 9.6 9.6 9.5 - 1.5 - - - - 8.4 - - - -
HERCA 7.2 7.8 8.3 3.2 9.7 9.7 9.6 9.6 6.9 9.5 9.5 9.4 9.4 - -
HINWO - - - - - - 8.4 0.9 - 0.9 - 2.5 8.0 - 9.3
KACJA 1.3 4.6 - - 8.8 3.5 - - - - - - - - -
4.2 - 1.4 5.4 7.3 - - 6.0 - 6.0 - - - - -
2.8 - 5.1 7.1 6.1 - 1.8 - - - - - 0.6 8.2 2.8
KOSDE - 2.3 - - - - - 8.2 7.9 - 6.8 3.3 - - -
LUNRO 4.8 8.5 - - - - - - - 3.9 - 8.3 9.0 4.5 -
MOLSI - - - - - - 6.0 - - - - - 7.9 - -
- - - 0.2 0.3 - 9.0 - - 0.3 - - 8.6 - 0.7
1.0 - 0.9 2.3 - 6.2 1.6 5.5 - - - - 0.7 - -
0.5 - - - - - - - - - - - 1.5 - -
PRZDA - - - 6.7 - - - - - - - - - - -
ROBBI 2.5 5.2 7.5 - - - 5.0 3.1 - - 1.8 - - - -
SLAST 0.7 - - 7.2 3.4 - - - - - - - 1.4 6.0 5.0
STOEN 1.2 8.2 - - 9.0 - 7.0 - - - - - 5.5 - -
STORO - - - - - - 8.3 - - - - - - - -
- - - - - 0.8 7.7 1.3 - - - - - - -
STRJO 1.0 - - 1.5 2.7 1.0 0.5 - 0.5 - 2.0 1.0 - 1.7 1.5
- - - - - - - - - - - 1.0 - - -
- - - - - - - - - - - 4.0 - - -
YRJIL 7.5 6.6 6.3 7.1 - - - - 1.4 6.2 0.7 - - 5.7 1.0
--------------------------------------------------------------------------------
Sum 48.6 59.1 55.3 60.6 61.3 29.7 83.1 39.3 27.6 29.8 34.3 31.3 52.9 28.1 23.6
Apr 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
--------------------------------------------------------------------------------
BENOR - - - - - 2.5 - - - - - 0.2 0.2 - -
- - - - - - - - - - - - - - -
BRIBE 6.3 6.2 2.9 - 6.0 8.4 2.3 - 0.7 1.0 3.8 2.3 0.3 1.4 2.7
CASFL - - - 6.4 - - 8.1 4.1 8.0 6.3 1.9 5.8 - - -
- - - 0.7 0.5 - 6.0 - - - - - - - -
CRIST - - - 1.0 - - - - - 7.8 - - - - -
GONRU - - - - - - - - - - - - 8.3 - 8.1
HERCA 7.6 3.3 6.1 9.2 7.2 9.1 7.7 9.1 8.9 9.0 3.0 8.9 8.9 7.8 5.8
HINWO - 3.3 - 7.0 5.5 - - 2.3 - - 4.2 7.1 - 7.0 -
KACJA - 1.8 - 5.2 - 3.5 3.3 4.7 2.3 3.4 7.6 7.9 7.8 - 5.7
- - - - - - - - 5.9 - - - - - -
- - - 6.4 1.2 3.3 1.2 5.0 3.2 2.9 5.2 7.1 2.0 0.6 -
KOSDE - - - - - 2.6 - - 5.0 - 1.5 - - 2.3 6.4
LUNRO - 2.0 8.7 1.0 - - 5.9 - - 8.2 8.1 7.9 4.2 7.4 -
MOLSI - - - - 3.4 - - 5.9 2.3 - 7.0 4.9 - 6.8 -
- 2.4 - 3.2 5.2 - - 1.0 0.6 2.8 3.8 2.7 - 7.6 -
- - 2.6 2.1 4.0 5.5 7.4 7.4 2.8 7.3 7.1 4.1 1.0 0.4 2.8
- - - - 6.1 6.0 6.0 6.5 1.7 4.3 5.8 6.0 - 1.1 1.9
PRZDA - - - - - - - 6.9 4.4 - - - - - -
ROBBI - - - - - - 2.0 1.1 5.1 6.0 - 3.9 - - 1.7
SLAST - - - 2.1 - - - 4.7 3.1 3.2 5.1 6.5 - - 1.4
STOEN - - - 7.4 4.2 - - - 7.9 - 2.4 6.1 - - -
STORO - - - - - - - - - - - - - - -
- - - - - - - - - - - - - - -
STRJO 2.1 0.5 0.9 0.5 4.5 4.7 1.0 1.1 - 1.0 1.3 1.5 - 5.0 2.3
1.7 - 1.0 - 3.5 - 5.4 1.0 - - 2.3 1.0 - 3.6 -
4.7 - 1.7 - 4.8 - 2.5 1.0 - - 4.0 2.7 - 3.9 -
YRJIL 2.8 - 3.9 5.3 5.2 3.8 4.9 4.2 4.6 3.7 2.6 - - 3.8 8.7
--------------------------------------------------------------------------------
Sum 25.2 19.5 27.8 57.5 61.3 49.4 63.7 66.0 66.5 66.9 76.7 86.6 32.7 58.7 47.5
3. Results (Meteors)
====================
Apr 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15
--------------------------------------------------------------------------------
BENOR - - - - - - 4 5 6 - - - - - -
- - - - - - 10 2 9 - - - - - -
BRIBE 1 - - - - 11 10 2 8 5 14 3 1 7 5
CASFL 1 - 16 9 7 - 2 - - 2 - - - - -
3 7 12 3 4 - 7 - - - - - - - -
CRIST - - - - 11 - - - - - - - - - -
GONRU 17 11 13 12 - 1 - - - - 11 - - - -
HERCA 10 5 11 4 14 16 9 8 3 12 10 10 9 - 7
HINWO - - - - - - 19 2 - 7 - 5 26 - -
KACJA 1 13 - - 14 5 - - - - - - - - -
3 - 2 7 8 - - 5 - 5 - - - - -
2 - 6 11 6 - 2 - - - - - 1 12 5
KOSDE - 5 - - - - - 7 11 - 11 7 - - -
LUNRO 7 12 - - - - - - - 10 - 30 30 20 -
MOLSI - - - - - - 75 - - - - - 92 - -
- - - 1 1 - 9 - - 2 - - 13 - 2
2 - 2 3 - 7 6 4 - - - - 1 - -
1 - - - - - - - - - - - 2 - -
PRZDA - - - 12 - - - - - - - - - - -
ROBBI 4 9 16 - - - 6 3 - - 3 - - - -
SLAST 1 - - 15 5 - - - - - - - 1 8 5
STOEN 3 15 - - 17 - 8 - - - - - 7 - -
STORO - - - - - - 25 - - - - - - - -
- - - - - 2 46 3 - - - - - - -
STRJO 2 - - 3 5 2 1 - 1 - 4 2 - 2 4
- - - - - - - - - - - 2 - - -
- - - - - - - - - - - 10 - - -
YRJIL 11 4 5 7 - - - - 1 7 1 - - 7 2
-------------------------------------------------------------------------------
Sum 69 81 83 87 92 44 239 41 39 50 54 69 183 56 30
Apr 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
--------------------------------------------------------------------------------
BENOR - - - - - 6 - - - - - 1 1 - -
- - - - - - - - - - - - - - -
BRIBE 9 11 7 - 15 23 6 - 3 2 10 5 1 4 4
CASFL - - - 16 - - 16 4 12 12 3 7 - - -
- - - 1 1 - 11 - - - - - - - -
CRIST - - - 3 - - - - - 15 - - - - -
GONRU - - - - - - - - - - - - 15 - 15
HERCA 10 7 3 13 15 20 28 17 13 12 4 9 10 12 4
HINWO - 3 - 13 10 - - 6 - - 12 18 - 19 -
KACJA - 4 - 9 - 20 5 8 3 3 11 15 6 - 14
- - - - - - - - 5 - - - - - -
- - - 12 2 4 3 10 3 3 7 7 2 1 -
KOSDE - - - - - 7 - - 7 - 3 - - 6 12
LUNRO - 4 18 1 - - 19 - - 15 21 25 27 12 -
MOLSI - - - - 23 - - 45 14 - 50 27 - 49 -
- 4 - 4 10 - - 2 2 5 5 4 - 10 -
- - 6 6 22 30 26 15 4 9 9 3 1 1 3
- - - - 17 31 29 28 3 20 12 14 - 4 2
PRZDA - - - - - - - 24 15 - - - - - -
ROBBI - - - - - - 2 3 10 12 - 11 - - 2
SLAST - - - 4 - - - 7 4 6 6 14 - - 1
STOEN - - - 27 10 - - - 17 - 3 13 - - -
STORO - - - - - - - - - - - - - - -
- - - - - - - - - - - - - - -
STRJO 3 1 2 1 9 14 3 2 - 2 2 3 - 7 5
4 - 2 - 10 - 12 2 - - 5 2 - 11 -
10 - 4 - 9 - 6 2 - - 7 7 - 12 -
YRJIL 1 - 8 9 15 14 26 11 11 7 3 - - 6 2
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Sum 37 34 50 119 168 169 192 186 126 123 173 185 63 154 64
Sirko Molau, 2008/06/02