Results of the IMO Video Meteor Network - August 2008
=====================================================
August leaves me with mixed impressions. Subjectively I would say, it was
a poor month (probably because I missed almost the complete Perseid maximum
because of clouds). However, looking at the network statistics, it couldn't
have been that poor. After all, there are six cameras with 25 and more
observing nights, which is only rarely achieved. At some observing sites
it was overcasted at the Perseid maximum, but there were 22 active cameras
on August 10/11 and only two observing sites could not provide data in
that night. In the second half of August the data got more sparse, but even
then there have been other months with much fewer observations.
So lets have a look at the overall statistics of August 2008. With roughly
2,100 hours of effective observing time, it ranks second after February
this year. Also those 14,000 meteors have only been beaten in August 2007
and October 2006. So it looks is if it was indeed a good month.
With respect to analyses, August was characterised by preparations for the
IMC, where I intended to present a new full analysis of the IMO Video Meteor
Database. To keep the analysis perfectly up to date, all observing data
until end of July 2008 were included - the last of which I received just
a week before the IMC. As in 2006, the analysis was carried out in two steps.
The computationally more demanding first step was to determine all active
radiants (alpha, delta, v_inf) at each solar longitude. Whereas the base
algorithm was left untouched (it was computed, with what probability each
meteor would belong to each possible radiant, these probabilities were
accumulated for each possible radiant, and finally the radiants with highest
probability were selected), I improved the procedure in some details to
make the results even more relevant. Details of these changes can be found
in my IMC presentation at http://www.imonet.org/imc08/imc08ppt.pdf.
Furthermore, the data set (360,000 meteors) had almost doubled compared
to 2006. Still, I could abstain from distributed computing, since I could
employ two IBM x3850 M2 servers with four quad core CPUs each in the test
lab of my company. Running on 30 CPU kernels in parallel, the calculation
was finished in roughly half a week. Once more, the result of the first step
has been made available online (http://www.imonet.org/imc08/radiants.html),
so everyone can look on his own for meteor showers, or can check in case of
suspected activity of an unknown shower, whether the radiant is also found
in the IMO video data.
The second step was to search for radiants with similar parameters in
subsequent solar longitude intervals, and to find meteor shower with longer
activity intervals. This part of the analysis was identical to 2006, so
there is still room for improvement. Contrary to last time, my IMC
presentation did not contain all showers detected, but only the most active
and long-lasting ones. In the following, I would like to present the results
for two typical August showers in detail.
First of all there is the most active shower in the video data - the Perseids.
With almost 18,000 meteors they make up for 5% of the full IMO Video Meteor
Database. The new "Handbook for Meteor Observers" of IMO lists an activity
interval from July 17 to August 24, which is a bit to short. In the video
data, the Perseid radiant shows up on July 9 for the first time, and remains
visible until August 27. As can be seen in the radiant plot (figure 1), the
drift is uniform between July 13 and August 25, i.e. in that time the shower
can be detected with high confidence. The position of the radiants fits well
to the ephemeris in all but the last 5 days - no wonder if you remember that
the list position was derived from our video data as well.
Figure 1: Perseid radiant position derived from nearly 18,000 shower members
(single station) of the IMO Video Meteor Database (red).
The activity profile of the Perseids (figure 2) shows a minor dip on July 19,
but otherwise a gradually but persistent increase. There is a small
pre-maximum on August 7/8, before the rate reduces a bit and reaches a
strong peak on August 12/13. The dip on August 9 is also known to visual
observers, even though the latest long-term activity profile given in the
IMO handbook (green dots) does not show it. The descending Perseid branch
is very steep, such that they are hardly recognizable anymore by August 20.
All in all, the video results fit very well to visual rates from the VMDB.
On the one hand that is due to the large data set. On the other hand it
still remarkable if you remember, that the video profile was derived only
from the number of Perseids and sporadic meteors, recorded with a wide
variety of video cameras. There were no limiting magnitudes, effective
observing times or r-value profiles involved.
Figure 2: Long-term activity profile of the Perseids derived from video data.
The blue dots mark the ZHR profile form the new IMO handbook with an
identical interval length of 2 degree.
For the second typical shower of August, the kappa-Cygnids, the situation
is a bit more tricky. According to the new IMO handbook, they are active
between August 3 and 25. They reach their maximum on August 17 (according
to the table) resp.19 (according to the activity profile in the handbook)
with an ZHR of 2. The radiant is almost stationary all the time. The 2006
video analysis revealed two showers (or two segments of the same shower)
near the expected position and with an activity interval of 20 days, but
with a different radiant drift velocity and direction. The new analysis
suggests that there might in fact be two showers with nearby radiants. Both
of them have a velocity of 23 km/s, i.e. a little less than the list value
of the kappa-Cygnids (25 km/s).
The primary shower was detected between August 5 and 26 with an overall
of 870 meteors. In the beginning, the radiant is roughly 10 degree south
of the expected KCG position (figure 3). The direction of the radiant drift
is about the expected one, only the drift velocity is much higher. Thus,
the radiant is nearly at the expected position by the end of the activity
interval. The activity profile (figure 4) is flat and shows only on
August 17 and 24/25 small raisings. The first one fits to the maximum from
the visual data.
The second shower was detected with about 700 meteors between August 7 and
25. It's radiant is roughly 5 to 10 degree west of the expected KCG position.
The scatter of the individual positions is much higher, but on average to
position of the radiants is almost constant as presented in the IMO handbook.
The maximum of this shower is on August 18 and comparable to the maximum of
the primary shower.
Figure 3: Radiant position of two August meteor showers which fit well to
the kappa-Cygnids.
Figure 4: Long-term activity profile of both August showers. The red line
is the accumulated activity of both, and the blue dots represent the ZHR
profile from the current IMO handbook.
It not possible to give final conclusions for the kappa-Cygnids yet. As
both showers are quite similar in many respects, but differ in radiant
position by about 10 degree, I would currently speak about two branches
of the same shower or an double radiant.
For comparison, a plot for August 18 based on the same data set was
obtained with the Radiant software. It also shows a double radiant, but
the primary shower is much stronger (figure 5). In fact, the picture
changes significantly if the standard deviation for velocity and position
errors are modified. This underlines that the last word on the kappa-Cygnids
is not yet spoken.
Figure 5: Radiant plot of August 18 (solar longitude 144-146) with the
Radiant software.
1. Observers
============
Code Name Place Camera FOV LM Nights Time Meteors
--------------------------------------------------------------------------------
BRIBE Brinkmann Herne HERMINE (0.8/6) 55 dg 3 mag 26 97.9 h 513
CASFL Castellani Monte Baldo BMH1 (0.8/6) 55 dg 3 mag 15 83.7 h 414
BMH2 (0.8/6) 55 dg 3 mag 27 127.4 h 519
CRIST Crivello Valbrevenna STG38 (0.8/3.8) 80 dg 3 mag 11 58.6 h 434
ELTMA Eltri Venezia MET38 (0.8/3.8) 80 dg 3 mag 15 100.0 h 706
GONRU Goncalves Tomar TEMPLAR1 (0.8/6) 55 dg 3 mag 27 187.5 h 1223
TEMPLAR2 (0.8/6) 55 dg 3 mag 3 18.0 h 106
HERCA Hergenroth. Tucson SALSA (1.2/4) 80 dg 3 mag 20 116.6 h 357
HINWO Hinz Brannenburg AKM2 (0.85/25) 32 dg 6 mag 13 82.8 h 340
KACJA Kac Kostanjevec METKA (0.8/8) 42 dg 4 mag 21 142.8 h 585
Kamnik REZIKA (0.8/6) 55 dg 3 mag 12 80.4 h 935
Ljubljana ORION1 (0.8/8) 42 dg 4 mag 29 162.8 h 870
ORION2 (0.8/8) 42 dg 4 mag 4 25.4 h 610
LUNRO Lunsford Chula Vista BOCAM (1.4/50) 60 dg 6 mag 9 36.0 h 808
MOLSI Molau Seysdorf AVIS2 (1.4/50) 60 dg 6 mag 13 52.2 h 1055
MINCAM1 (0.8/6) 55 dg 3 mag 27 124.3 h 516
Ketzuer REMO1 (0.8/3.8) 80 dg 3 mag 23 97.8 h 693
REMO2 (0.8/3.8) 80 dg 3 mag 25 100.0 h 742
SLAST Slavec Ljubljana KAYAK1 (1.8/28) 50 dg 4 mag 15 88.3 h 284
STOEN Stomeo Scorze MIN38 (0.8/3.8) 80 dg 3 mag 16 108.0 h 593
STRJO Strunk Herford MINCAM2 (0.8/6) 55 dg 3 mag 21 63.1 h 300
MINCAM3 (0.8/8) 42 dg 4 mag 17 61.5 h 273
MINCAM5 (0.8/6) 55 dg 3 mag 19 61.1 h 426
WEBMI Weber Chouzava TOMIL (1.4/50) 50 dg 6 mag 5 11.1 h 272
YRJIL Yrjola Kuusankoski FINEXCAM (0.8/6) 55 dg 3 mag 13 68.6 h 221
--------------------------------------------------------------------------------
Sum 31 2155.4 h 13785
2. Observing Times (h)
======================
Aug 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15
--------------------------------------------------------------------------------
BRIBE 6.3 0.3 - 4.8 1.8 5.5 2.1 3.7 - 5.9 1.8 7.9 8.0 7.4 7.0
CASFL - 4.9 7.2 7.3 - - 6.5 6.0 7.6 7.6 7.7 3.6 1.0 - -
- 3.9 3.5 7.3 0.5 - 2.8 7.5 7.6 7.6 6.5 4.6 2.9 - -
CRIST - 6.0 - - - - - 4.2 7.5 7.6 7.4 - - 0.5 6.7
ELTMA 4.2 7.3 7.2 7.5 5.0 - 7.6 - 6.5 7.6 7.3 7.5 - - -
GONRU - - - 7.0 7.6 6.0 7.7 8.1 8.0 - 2.3 7.9 8.2 8.2 1.6
- - - - 6.6 4.2 - - 7.2 - - - - - -
HERCA 5.2 6.3 5.7 - 2.6 4.5 7.9 2.3 8.7 5.4 8.6 7.0 8.0 - -
HINWO - 0.6 - - 6.6 3.3 - - 5.1 4.5 23 - - - -
KACJA - 4.5 7.4 - - 7.0 7.5 - 7.5 7.4 7.7 7.5 - 7.6 -
- - - - - - 6.3 - 6.9 6.8 6.3 - 1.1 - -
3.8 5.2 7.5 1.3 0.3 7.6 7.6 0.9 7.7 7.8 7.9 7.4 1.9 5.9 -
- - - - - 4.6 - - 5.8 7.2 7.8 - - - -
LUNRO - 2.5 - - - - - 6.8 5.6 7.6 3.5 6.0 - - -
MOLSI - - - - - 5.0 1.2 0.5 - - - - 4.9 1.3 -
- 1.4 6.1 1.2 7.2 7.3 1.8 4.9 4.5 7.5 0.2 - 1.7 - 0.3
- - 2.8 6.4 6.4 6.4 2.5 3.7 5.3 5.0 - 2.5 7.0 4.1 3.7
- 0.7 3.3 6.4 6.5 6.4 2.4 3.2 5.8 3.5 - 2.6 6.5 5.7 1.3
SLAST 3.5 5.6 6.7 - - - - - 4.8 7.1 7.3 7.3 - 5.0 -
STOEN 2.7 7.0 7.1 6.1 5.3 - 7.2 - 7.3 7.4 7.5 7.5 - - -
STRJO - - - 4.1 2.4 5.7 1.1 2.9 - 4.5 - 3.3 4.3 1.6 2.7
- - - 4.4 0.8 5.7 2.0 3.7 - 4.7 - 0.5 5.2 3.2 5.4
3.4 - - 3.7 1.3 5.1 2.3 3.8 - 2.7 - 3.4 4.6 2.2 5.5
WEBMI - - - - - 2.4 - - - 1.4 - - 1.8 - -
YRJIL - 2.9 - 3.0 32 - - - 3.6 2.7 3.0 - - - 2.5
--------------------------------------------------------------------------------
Sum 29.1 59.1 64.5 70.5 92.9 86.7 76.5 62.2123.0129.5115.8 86.5 67.1 52.7 36.7
Aug 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
-------------------------------------------------------------------------------------
BRIBE 4.6 0.3 5.0 2.3 5.4 0.8 1.2 2.8 - 2.2 0.3 - - 3.6 5.2 1.7
CASFL - 7.9 8.1 - - - - - - - - - - 4.3 3.2 0.8
0.5 7.0 7.6 2.8 5.2 4.8 7.3 2.5 5.9 7.0 4.5 3.6 5.1 6.7 1.7 0.5
CRIST 1.1 2.1 - - - - - 7.0 - - - - - - 8.5 -
ELTMA 2.3 6.0 - 8.0 - 8.1 - - 7.9 - - - - - - -
GONRU 7.1 8.2 6.5 8.2 8.7 5.0 8.8 7.5 6.5 3.9 3.7 8.9 9.0 4.7 9.0 9.2
- - - - - - - - - - - - - - - -
HERCA 7.2 2.0 - - - - 8.2 6.7 8.3 3.2 - - 4.2 - 4.6 -
HINWO 6.6 4.8 5.9 - - - - - - - 5.6 5.5 - 3.1 8.2 -
KACJA 5.1 - 5.8 6.2 - 8.3 6.1 - 8.5 5.1 7.9 8.5 5.4 5.1 - 6.7
- - 6.9 8.1 - - 6.1 - 8.5 - 8.6 7.3 7.5 - - -
3.1 4.9 7.2 8.3 0.8 4.5 8.4 - 6.8 8.6 8.6 8.6 7.1 6.8 0.8 5.5
- - - - - - - - - - - - - - - -
LUNRO 1.0 - - 1.0 2.0 - - - - - - - - - - -
MOLSI - 1.5 - - - - - 1.6 - 4.5 6.8 6.2 4.9 5.8 8.0 -
7.9 5.4 7.0 - 4.2 4.2 0.4 2.3 8.4 6.6 8.5 8.6 5.6 4.2 6.4 0.5
0.7 6.2 1.4 0.3 3.9 4.0 - 3.8 - - - - 0.3 4.2 8.3 8.4
- 6.7 1.4 3.8 4.4 3.3 - 3.8 - 0.6 - 1.2 0.2 3.7 8.3 8.3
SLAST - - - - - - - - 6.4 8.7 8.1 - 8.6 6.4 0.9 1.9
STOEN - - 7.9 - 1.9 8.2 - - 8.1 8.3 - - 8.5 - - -
STRJO 1.2 0.5 1.0 1.3 - 1.2 - 4.6 - 3.5 0.2 - - 7.9 6.9 2.2
4.7 0.5 2.2 2.2 - - - - - 0.5 - - - 7.9 7.9 -
4.8 0.3 0.5 0.5 - - - - - 0.8 - - - 7.1 6.9 2.2
WEBMI - - - - - - - - - - 2.5 2.0 - - - 1.0
YRJIL - - - 3.7 - 0.4 4.3 4.6 - - - - - - 2.0 3.9
-------------------------------------------------------------------------------------
Sum 57.9 64.3 74.4 56.7 36.5 52.8 50.8 47.2 75.3 63.5 65.3 60.4 66.4 81.5 96.8 52.8
3. Results (Meteors)
====================
Aug 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15
--------------------------------------------------------------------------------
BRIBE 23 2 - 20 8 25 7 13 - 23 11 106 79 31 34
CASFL - 32 36 33 - - 23 25 37 58 59 31 9 - -
- 15 13 33 4 - 11 48 41 55 51 62 17 - -
CRIST - 31 - - - - - 49 70 72 78 - - 4 39
ELTMA 24 47 46 42 13 - 40 - 39 66 126 140 - - -
GONRU - - - 26 46 14 45 90 83 - 19 149 79 73 7
- - - - 54 18 - - 34 - - - - - -
HERCA 11 32 19 - 5 8 34 6 18 25 35 35 30 - -
HINWO - 2 - - 56 23 - - 34 28 22 - - - -
KACJA - 17 29 - - 33 29 - 29 51 74 104 - 26 -
- - - - - - 78 - 81 143 202 - 11 - -
10 13 39 6 1 45 43 1 52 87 140 134 14 17 -
- - - - - 76 - - 101 179 254 - - - -
LUNRO - 13 - - - - - 56 52 81 212 383 - - -
MOLSI - - - - - 142 15 12 - - - - 154 11 -
- 5 40 1 35 42 13 17 21 82 1 - 7 - 2
- - 12 45 62 45 12 38 46 54 - 30 122 24 39
- 2 17 43 69 68 12 41 51 25 - 54 125 40 8
SLAST 5 12 20 - - - - - 11 32 48 70 - 10 -
STOEN 11 36 33 36 18 - 26 - 39 65 134 63 - - -
STRJO - - - 21 5 31 3 16 - 25 - 64 33 5 8
- - - 16 2 20 5 18 - 29 - 13 49 8 28
27 - - 27 5 26 6 39 - 13 - 123 63 9 27
WEBMI - - - - - 83 - - - 85 - - - - -
YRJIL - 2 - 24 27 - - - 15 27 39 - 5 - 13
-------------------------------------------------------------------------------
Sum 111 261 304 373 410 699 402 469 854 1305 1505 1561 797 258 205
Aug 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
------------------------------------------------------------------------------------
BRIBE 18 1 15 10 13 3 4 13 - 7 1 - - 19 19 8
CASFL - 25 30 - - - - - - - - - - 6 8 2
1 20 30 7 10 12 11 14 10 15 7 5 11 13 2 1
CRIST 14 17 - - - - - 33 - - - - - - 27 -
ELTMA 6 30 - 28 - 35 - - 24 - - - - - - -
GONRU 27 63 38 56 48 15 51 38 37 8 9 53 38 13 33 65
- - - - - - - - - - - - - - - -
HERCA 16 14 - - - - 19 11 18 7 - - 7 - 7 -
HINWO 22 14 32 - - - - - - - 25 16 - 9 57 -
KACJA 10 - 17 12 - 17 16 - 34 9 27 19 12 8 - 12
- - 52 45 - - 49 - 80 - 78 66 50 - - -
8 20 26 27 3 9 28 - 23 28 25 25 19 12 2 13
- - - - - - - - - - - - - - - -
LUNRO 2 - - 4 5 - - - - - - - - - - -
MOLSI - 8 - - - - - 24 - 69 142 135 56 134 153 -
27 26 30 - 22 9 3 8 21 16 23 22 5 12 23 3
3 36 6 1 9 12 - 12 - - - - 1 17 44 23
- 26 9 7 12 18 - 16 - 4 - 1 1 17 52 24
SLAST - - - - - - - - 7 18 16 - 16 13 2 4
STOEN - - 40 - 2 18 - - 26 25 - - 21 - - -
STRJO 3 2 3 5 - 3 - 20 - 7 1 - - 20 16 9
21 1 6 7 - - - - - 2 - - - 20 28 -
16 1 1 2 - - - - - 2 - - - 13 20 6
WEBMI - - - - - - - - - - 43 50 - - - 11
YRJIL - - - 8 - 1 20 20 - - - - - - 5 15
------------------------------------------------------------------------------------
Sum 194 304 335 219 124 152 201 209 280 217 397 392 237 326 498 196
Sirko Molau, 2008/10/08