Results of the IMO Video Meteor Network - October 2008
======================================================
Once more, the previous month set new standards. The astronomical conditions
were not perfect, since the waning moon hindered Orionid observations
significantly, but the weather was cooperative at many sites. Carl Hergenrother
was again on top of the list. He missed only a single night and managed for
the first time to obtain more than 300 hours of effective observing time. Carl
wrote that because of the drought in Arizona he would even welcome a few more
clouds with rain. ;-) Also our second American observer Bob Lunsford, Rui
Goncalves from Portugal, and my two cameras near Berlin managed to get 25 and
more observing nights. All in all there were 10 cameras with 20 and more
nights.
The analysis of visual observation revealed, that the Orionid activity did
not reach the same level as in 2007, but was still significantly above the
long-term value of the years before 2006.On October 19/20 and 20/21 alone,
more than 4,000 meteors could be recorded. In total we got over 2,750
observing hours, which is a plus of 300 hours compared to the best month
February 2008. With more than 17,000 meteors, also the previously best count
of October 2006 was outbid by 2,000 meteors.
By the end of October, the number of meteors in the IMO Video Meteor Database
had grown to 400,000, just one year after we reached 300,000 in October 2007.
It shows that the video network and the database linked to it continues to
grow. However, sometimes there is also sad news, as a few days ago when he
learnt that our oldest video observer submitted his last observation in
October. We mourn for Milos Weber, who died on November 12 at the age of 88.
Not only because of the long nights and the enhanced meteor activity October
is an intersting month - there is hardly another month with so many known
meteor showers and further ones waiting for their detection. The Leo-Minorids
were included in the IMO Working List during the last revision. With the
October-Camelopardalids and the eta Ursa Majorids, two new showers could be
identified in the last fews year, and in 2007 another meteor shower candidate
was found (iota Cancrids). The more data we have, the better even minor
showers with ZHRs of one stand out from the sporadic background and can
subsequently be detected by statistical means. In the following, however,
I will concentrate on the major showers of October.
According to the latest edition of the IMO handbook, the Orionids are active
between October 2 and November 7. In that time, the radiant moves from
northern Orion towards Gemini. In the 2008 meteor shower analyses, the
Orionids could be tracked with 14,000 shower members over a much longer time
interval, namely September 3 till November 21. However, the radiant position
in the first and last few days is quite uncertain and it cannot be said at
exactly when the shower raises for the first time above the sporadic
background. The radiant is well-defined between September 28 and November 10
(figure 1). In that interval, its position and drift agrees well with the
values from the IMO handbook. The velocity of the Orionids computed from the
video data fits also to the value found in the literature (66 km/s).
Figure 1: Radiant position of the Orionids from data of the IMO Video Meteor
Database.
According to the IMO handbook, the maximum of the Orionids is on October 21.
The peak ZHR has been roughly 20 until 2005. In the last two years, however,
the Orionid activity was much stronger over a period of several days with
peak ZHRs of 50 (2006) and 70 (2007). The reason was found to be meteoroids
trapped in a 1:6 resonance with Jupiter. The 2008 live ZHR profile of IMO
revealed, that also this year the rates where higher, even though the peak
ZHR was only of the order of 40.
Data from 2006 till 2008 were used for the activity analysis presented here.
The ratio of the number of Orionids and sporadic meteors per night was taken
as a measure of activity. Only those cameras from the time interval October
17/18 to 26/27 were used, which were active all night long with only minor
interruptions. Since the observing conditions (moon) and the cameras (with
and without image intensifier) were highly variable from one night to the
next, there is significant scatter in the data. On the other hand, the data
set (2006: 3258 ORI / 2433 SPO; 2007: 2390 ORI / 1076 SPO;
2008: 4113 ORI / 2486 SPO) was large enough to smooth out the activity
profile statistically.
Figure 2 presents the resulting activity profile from the three years 2006
till 2008. It is confirmed, that the Orionid peak was highest in 2007,
even though the descending branch could not be observed last year due to
poor weather. The maximum rates vary only little between 2006 and 2008.
However, it should be noted that according to visual observations the
Orionids peaked already on October 21, 2008, whereas the video data show
a second, slightly higher peak 36 hours later.
Figure 2: Comparison of the activity profiles (only maximum times) of the
Orionids in the years 2006 till 2008.
When comparing the long-term activity profiles from visual and video data
(figure 3) one should note, that the visual profile is based only on data
from the "normal" years until 2005, whereas most of the video data were
obtained in 2006 and 2007. Until October 18, both profiles agree well.
Thereafter the activity from the peak years 2006 and 2007 is dominating.
It's interesting to see, that the surplus in activity holds not only for
the Orionid maximum, but for the whole descending activity branch until the
end of the visual observing period.
Figure 3: Long-term activity profile of the Orionids. The blue dots
correspond to the ZHR profile from the current edition of the IMO handbook
(without the years 2006 and 2007).
Whereas in the old IMO handbook a number of ecliptical sources where listed
as individual meteor showers, they were combined to the Antihelion source
in the last revision of the meteor shower list. The only exception are the
northern and southern Taurids between September 25 and November 25, which
are still listed as independent showers. In our video data, the northern
Taurids are clearly identified between October 20 and November 29, i.e. the
radiant position shows only little scatter in that time interval and fits
well to the position given in the IMO handbook. In total, the radiant could
be traced with 4,500 shower members between October 1 and December 11, but
there is significant scatter in the individual positions of the first and
last few days (figure 4).
Figure 4: Radiant position of the northern and southern Taurids from data
of the IMO Video Meteor Database.
The activity interval of the southern Taurids starts a little earlier. In
our video data, they are identified with a total of 6,800 shower members
between September 8 and November 30. The radiant is well-defined between
September 18 and November 26, where it lies constantly about one or two
degrees south of the position given in the IMO handbook.
According to the IMO handbook, the activity of the northern and the southern
branch varies, whereby activity of the southern Taurids ends a week earlier.
The activity profile obtained in the 2008 analysis of the video meteor
database (figure 5) draws a more accurate picture. Both showers have a clear
activity profile of their own. At first, the southern Taurids (blue) dominate.
They reach their maximum around October 12 and loose strength thereafter,
whereas the activity of the northern Taurids (red) is increasing in parallel.
In early November, both branches are of about the same strength, and then
the northern Taurids with their maximum around November 11 dominate. The
breakdown in activity near solar longitude 236 is not real but an artefact
from the Leonids.
Figure 5: Activity profile of the northern (red) and southern (blue) Taurids.
The green line is the resulting total activity from both branches.
In the last few days there have been hints, that the fraction of bright
Taurids and fireballs early November 2008 was higher than usual. A preliminary
analysis of visual data, however, revealed the same population index as in
the years before. Here I tried for the first time to analyse the brightness
data of video meteors. The average brightness of all Taurids and sporadic
meteors from one night was computed and subtracted from each other. Figure 6
shows the development of the brightness difference for the years 2006 till
2008, averaged in a sliding 3-day interval. On average, the Taurids were
0.2 mag fainter than the sporadic meteors. That value shows some scatter
from one night to the next, but there is no indication that the 2008 Taurids
were brighter than in previous years. Only towards the end of the month
such a deviation may be suggested. In remains to see whether this trend
continues in November.
Figure 6: Mean brightness difference between the Taurids and sporadic
meteors in the years 2006 till 2008.
Lets have a brief look at the Leo-Minorids in the end. As mentioned before,
this shower has been included in the IMO working list in the last revision,
after among others also our video data confirmed their existence. The
handbook lists an activity interval from October 19 till 27 with a maximum
at October 24. This shower has been detected in the 2008 analysis of the
video meteor database, too. Over 700 meteors recorded between October 17
to 27 confirm both the position and the drift of the radiant (figure 7).
The velocity of the Leo-Minorids was determined to 61 km/s in the video data,
which is a little less than the value from the meteor shower list (62 km/s).
Figure 7: Radiant position of the Leo-Minorids from data of the IMO Video
Meteor Database.
The activity profile of the shower (figure 8) is well-shaped. The maximum
occurs on October 23/24. The peak activity is comparable to the northern
Taurids and should therefor be of the order of ZHR=4 and not ZHR=2 as
presented in the IMO handbook.
Figure 8: Activity profile of the Leo-Minorids.
1. Observers
============
Code Name Place Camera FOV LM Nights Time Meteors
--------------------------------------------------------------------------------
BENOR Benitez-S. Las-Palmas TIMES5 (0.95/50) 10 dg 3 mag 3 13.5 h 34
BRIBE Brinkmann Herne HERMINE (0.8/6) 55 dg 3 mag 20 115.1 h 748
CASFL Castellani Monte Baldo BMH2 (0.8/6) 55 dg 3 mag 16 69.9 h 220
CRIST Crivello Valbrevenna STG38 (0.8/3.8) 80 dg 3 mag 2 19.1 h 76
Genova C3P8 (0.8/3.8) 80 dg 3 mag 14 96.5 h 484
ELTMA Eltri Venezia MET38 (0.8/3.8) 80 dg 3 mag 6 43.8 h 281
GONRU Goncalves Tomar TEMPLAR1 (0.8/6) 55 dg 3 mag 25 192.6 h 1516
HERCA Hergenroth. Tucson SALSA (1.2/4) 80 dg 3 mag 30 304.0 h 1071
HINWO Hinz Brannenburg AKM2 (0.85/25) 32 dg 6 mag 16 103.9 h 697
KACJA Kac Kostanjevec METKA (0.8/8) 42 dg 4 mag 21 166.6 h 642
Kamnik REZIKA (0.8/6) 55 dg 3 mag 13 108.1 h 1144
Ljubljana ORION1 (0.8/8) 42 dg 4 mag 23 83.6 h 215
KOSDE Koschny Noordwijkerh. TEC1 (1.4/12) 30 dg 4 mag 12 57.3 h 89
LUNRO Lunsford Chula Vista BOCAM (1.4/50) 60 dg 6 mag 26 222.7 h 2070
MOLSI Molau Seysdorf AVIS2 (1.4/50) 60 dg 6 mag 13 87.2 h 1584
MINCAM1 (0.8/6) 55 dg 3 mag 24 97.0 h 456
Ketzuer REMO1 (0.8/3.8) 80 dg 3 mag 25 173,4 h 827
REMO2 (0.8/3.8) 80 dg 3 mag 26 150.6 h 625
PRZDA Przewozny Berlin ARMEFA (0.8/6) 55 dg 3 mag 13 94.2 h 418
SLAST Slavec Ljubljana KAYAK1 (1.8/28) 50 dg 4 mag 18 71.0 h 157
STOEN Stomeo Scorze MIN38 (0.8/3.8) 80 dg 3 mag 14 107.2 h 496
STORO Stork Kunzak KUN1 (1.4/50) 55 dg 6 mag 2 11.6 h 565
Ondrejov OND1 (1.4/50) 55 dg 6 mag 3 12.8 h 577
STRJO Strunk Herford MINCAM2 (0.8/6) 55 dg 3 mag 24 85.1 h 414
MINCAM3 (0.8/8) 42 dg 4 mag 15 82.6 h 400
MINCAM5 (0.8/6) 55 dg 3 mag 15 90.7 h 772
WEBMI Weber Chouzava TOMIL (1.4/50) 50 dg 6 mag 1 2.4 h 93
YRJIL Yrjola Kuusankoski FINEXCAM (0.8/6) 55 dg 3 mag 16 98.6 h 367
--------------------------------------------------------------------------------
Overall 31 2761.1 h 17038
2. Observing Times (h)
======================
Oct 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15
--------------------------------------------------------------------------------
BENOR - - - - - - - - - - - - - - -
BRIBE 4.3 4.6 0.9 0.8 - - 0.3 1.6 8.7 7.6 4.0 9.7 0.3 - -
CASFL 0.6 - - 2.0 1.7 - - - - 6.6 11.1 7.1 4.8 5.4 2.5
CRIST - - - 10.1 - - - - - - - - - - -
- - 9.0 3.8 2.1 - - 7.6 9.6 9.5 10.3 10.2 3.5 8.7 -
ELTMA - - - - 7.1 - - - - - 9.0 - - - -
GONRU 10.2 9.9 10.7 10.8 10.5 4.8 0.6 9.9 9.7 - 2.2 10.0 6.9 2.4 4.2
HERCA 10.6 10.6 8.0 5.5 - 10.0 9.4 10.8 10.4 10.8 9.8 5.1 10.9 6.9 11.0
HINWO 1.5 - - 5.9 3.6 - 10.0 6.8 - 1.8 10.7 5.8 - - -
KACJA - - - 10.2 11.0 11.1 10.0 6.8 0.4 4.3 6.9 7.0 5.6 - 5.8
- - - 8.6 7.0 9.5 3.8 - 2.5 - 11.1 11.1 - 1.4 -
- - - 3.4 10.5 6.7 0.7 5.6 4.8 0.8 0.9 1.5 1.5 2.1 4.0
KOSDE 2.7 - - - - 1.2 - 8.4 5.3 8.9 - 2.4 - - -
LUNRO 9.8 10.4 8.0 - - 10.5 10.4 10.4 10.6 - 3.1 8.6 8.2 2.0 10.8
MOLSI 6.6 - - 9.3 - - 3.7 3.6 1.7 - - - - - -
7.2 - 0.8 8.9 0.3 0.5 4.6 4.1 2.1 - - 1.9 0.4 0.4 1.0
10.6 10.6 10.7 10.8 - 0.3 9.5 5.5 11.1 6.1 8.6 11.2 2.1 - -
10.6 10.6 10.7 10.7 - 0.1 5.4 6.0 6.6 6.0 5.1 9.1 - - -
PRZDA 9.9 10.7 - 10.8 - - 3.2 3.1 11.1 6.7 5.0 4.9 - - -
SLAST - - - 0.5 10.0 7.8 3.0 8.0 4.7 4.3 2.7 - 1.8 0.7 0.9
STOEN - - 10.4 9.2 2.5 9.6 - - 7.7 10.8 8.7 - - 4.5 4.1
STORO - - - - - - - - - - - - - - -
- - - - - - - - - - - - - - -
STRJO 2.1 0.5 1.5 1.0 - 0.2 1.8 - 8.7 6.9 1.0 2.2 0.2 - -
- - 1.5 - - - - - 8.4 10.3 0.6 3.0 - - -
- - 1.5 - - - - - 9.6 9.1 0.7 3.7 - - -
WEBMI - - - - - - - - - - - - - - -
YRJIL - - 5.1 - - 10.6 10.2 10.8 - 5.5 6.9 10.7 - 4.2 3.7
--------------------------------------------------------------------------------
Sum 86.7 67.9 78.8122.3 66.3 82.9 86.6109.0133.7116.0118.4125.2 46.2 38.7 48.0
Oct 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
-------------------------------------------------------------------------------------
BENOR - - - - 6.5 2.5 - - - - - - - - - 4.5
BRIBE 6.7 6.4 8.8 9.7 7.7 4.4 12.5 10.2 - 5.9 - - - - - -
CASFL - - - - 0.7 - 1.8 1.9 1.4 11.4 10.7 - - 0.2 - -
CRIST - - - - - - - - - 9.0 - - - - - -
- - 9.9 7.2 - 1.5 - - - - 3.6 - - - - -
ELTMA - - - 9.2 2.9 - 5.6 - - 10.0 - - - - - -
GONRU 0.4 - 8.9 10.3 - - 7.9 10.1 11.6 11.0 10.0 - 7.7 5.4 - 6.5
HERCA 11.0 7.0 11.1 11.1 11.1 10.2 11.2 11.2 11.2 11.3 11.0 11.3 11.3 11.4 11.4 11.4
HINWO - 2.8 - 11.1 11.2 11.2 - 0.5 - 8.3 10.4 - - - 2.3 -
KACJA - 7.1 11.4 11.3 10.5 11.6 8.1 - - - 11.3 2.9 - - 10.6 2.7
- - 11.5 11.5 11.5 8.7 9.9 - - - - - - - - -
- 1.5 7.1 6.7 4.2 5.0 5.6 1.9 3.0 - 0.8 - - 1.2 4.1 -
KOSDE - 3.8 3.9 8.8 - - - - - - - 4.7 - 5.9 1.3 -
LUNRO 10.2 10.7 10.9 8.0 - 4.0 1.8 9.0 10.5 10.4 11.1 3.9 9.0 9.8 10.6 -
MOLSI - 10.2 7.5 10.2 10.8 5.6 - 6.5 - 6.3 - - - - 5.2 -
2.5 11.6 6.8 8.7 11.8 5.3 - 7.0 - 4.1 0.1 - - - 5.0 1.9
1.6 10.4 6.4 6.6 11.8 - 6.9 12.0 3.0 8.6 - 7.2 - 0.4 0.1 1.3
3.5 8.8 8.3 6.7 11.8 0.3 6.8 7.0 2.9 6.1 - 3.2 0.2 0.8 0.5 2.8
PRZDA - - - - 11.8 - - 9.5 - - - 4.5 - - - 3.0
SLAST - - 1.3 2.2 3.6 7.3 6.0 - - - 2.4 - - - 3.8 -
STOEN - - 10.0 9.2 1.2 - - - - 11.6 7.7 - - - - -
STORO - - - - 8.5 3.1 - - - - - - - - - -
- - - 2.1 8.4 2.3 - - - - - - - - - -
STRJO 5.2 1.7 3.2 7.4 5.5 1.0 4.7 11.5 - 1.8 - 8.8 7.2 0.5 - 0.5
4.7 3.5 4.2 7.6 5.2 - 9.0 11.4 - 1.2 - 8.0 4.0 - - -
7.2 4.0 2.5 8.6 6.8 - 9.2 11.6 - 2.1 - 10.0 4.1 - - -
WEBMI - - - - 2.4 - - - - - - - - - - -
YRJIL - - 6.6 3.3 1.3 - 10.7 3.7 - - - 0.5 4.8 - - -
-------------------------------------------------------------------------------------
Sum 53.0 89.5140.3177.5167.2 84.0117.7125.0 43.6119.1 79.1 65.0 48.3 35.6 54.9 34.6
3. Results (Meteors)
====================
Oct 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15
--------------------------------------------------------------------------------
BENOR - - - - - - - - - - - - - - -
BRIBE 16 25 5 3 - - 1 4 39 46 24 63 1 - -
CASFL 2 - - 6 2 - - - - 11 37 14 11 10 9
CRIST - - - 25 - - - - - - - - - - -
- - 59 22 16 - - 54 42 35 46 47 7 29 -
ELTMA - - - - 32 - - - - - 37 - - - -
GONRU 57 63 74 66 80 15 2 56 67 - 7 39 30 5 10
HERCA 19 27 15 16 - 20 19 22 21 30 17 16 19 21 25
HINWO 2 - - 55 11 - 58 26 - 12 79 39 - - -
KACJA - - - 24 31 25 32 15 1 17 23 22 15 - 14
- - - 68 93 55 16 - 5 - 79 71 - 2 -
- - - 4 33 9 1 8 8 2 1 3 2 2 7
KOSDE 3 - - - - 1 - 10 5 11 - 2 - - -
LUNRO 73 81 24 - - 75 72 90 67 - 17 64 48 2 44
MOLSI 128 - - 285 - - 64 37 7 - - - - - -
20 - 4 20 1 2 11 5 1 - - 2 2 1 1
40 38 43 36 - 2 19 8 32 28 16 30 4 - -
50 39 45 29 - 3 14 8 10 17 12 18 - - -
PRZDA 40 51 - 42 - - 10 18 38 24 10 15 - - -
SLAST - - - 1 24 16 8 17 5 6 4 - 4 1 2
STOEN - - 34 36 6 27 - - 24 42 36 - - 12 5
STORO - - - - - - - - - - - - - - -
- - - - - - - - - - - - - - -
STRJO 9 2 5 4 - 1 4 - 21 22 4 4 1 - -
- - 3 - - - - - 16 22 2 8 - - -
- - 5 - - - - - 34 35 2 11 - - -
WEBMI - - - - - - - - - - - - - - -
YRJIL - - 14 - - 51 43 44 - 14 15 33 - 17 13
--------------------------------------------------------------------------------
Sum 459 326 330 742 329 302 374 422 443 374 468 501 144 102 130
Oct 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
-------------------------------------------------------------------------------------
BENOR - - - - 19 8 - - - - - - - - - 7
BRIBE 21 31 47 142 31 23 132 70 - 24 - - - - - -
CASFL - - - - 4 - 6 14 3 58 32 - - 1 - -
CRIST - - - - - - - - - 51 - - - - - -
- - 52 54 - 9 - - - - 12 - - - - -
ELTMA - - - 82 6 - 23 - - 101 - - - - - -
GONRU 1 - 78 94 - - 179 135 121 135 67 - 91 24 - 20
HERCA 27 30 40 70 80 74 74 71 48 62 43 38 38 35 26 28
HINWO - 18 - 86 110 96 - 1 - 57 37 - - - 10 -
KACJA - 37 50 76 65 98 29 - - - 32 2 - - 29 5
- - 108 179 177 158 133 - - - - - - - - -
- 3 17 13 27 12 21 21 3 - 1 - - 9 8 -
KOSDE - 5 5 28 - - - - - - - 5 - 11 3 -
LUNRO 56 68 61 31 - 215 138 129 121 120 91 131 97 91 64 -
MOLSI - 122 93 177 298 97 - 112 - 83 - - - - 81 -
12 63 34 76 122 38 - 15 - 6 1 - - - 16 3
8 33 39 51 154 - 97 86 8 22 - 27 - 1 1 4
8 19 37 52 172 1 26 21 10 15 - 10 1 1 2 5
PRZDA - - - - 91 - - 53 - - - 11 - - - 15
SLAST - - 3 4 10 19 22 - - - 4 - - - 7 -
STOEN - - 62 76 1 - - - - 103 32 - - - - -
STORO - - - - 516 49 - - - - - - - - - -
- - - 99 431 47 - - - - - - - - - -
STRJO 16 6 10 55 25 5 62 74 - 10 - 40 32 1 - 1
13 13 17 51 34 - 89 80 - 5 - 33 14 - - -
30 29 10 114 55 - 162 144 - 9 - 87 45 - - -
WEBMI - - - - 93 - - - - - - - - - - -
YRJIL - - 31 7 1 - 50 15 - - - 1 18 - - -
-------------------------------------------------------------------------------------
Sum 192 477 794 1617 2522 949 1243 1041 314 861 352 385 336 174 247 88
Sirko Molau, 2008/11/24