[Meteor-Scatter] Leonids peak

[David Butler]

John Peters wrote:
> 
> Hi,
> 
> anyone out here who dares to predict the peak of the Leonids shower ??? I'm
> curious..
> 
> 73! John PA5MS
> 
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Hi DXers,

Very soon the Earth is going to pass through a belt of interplanetary
debris called the Leonids meteor shower. This meteor stream occurs every
year in the period November 14-21 and in 2003 the maximum shower
activity will occur on **Tuesday November 18**. Keen v.h.f. operators
can make use of the shower by beaming towards the ionised trails and
scattering their signals well beyond the horizon. Meteor trails ionise
at a height of around 90-110km in an area of the ionosphere designated
the E-layer. With ionisation occurring at this height it is possible to
scatter signals up to 2000km away although most contacts you'll probably
make will lie in the range between 1200 to 1600km. Normally the shower
is fairly diffuse with very little activity being noted. However
previous observations of the Leonid meteor shower have shown that
approximately every 33 years the shower can reach storm proportions. A
major peak occurred in 1966 and very recently in 1998 and 2001 the
reflections from the Leonid meteors have been excellent. 

Last Six Years 
I've been active during the Leonids meteor shower for over 20 years and
my records show that conditions in the last six years (with one
exception) have been very good. 

During the Leonids shower in 1997 I made 27 s.s.b. contacts on the 
144MHz band with stations in 11 countries, DL (Germany), EA (Spain), 
F (France), HA (Hungary), HB9 (Switzerland), I (Italy), LA (Norway), 
OE (Austria), S5 (Slovenia), YU (Yugoslavia) and 9A (Croatia).
It was difficult to assess when the peak occurred but certainly
conditions appeared to be excellent between 0700-0800UTC and
0915-1000UTC. My longest distances contacted included the stations of
YU7EW (1859km), I8MPO (1829km) and I8TWK (1827km). 

Conditions in 1998 were absolutely fantastic with the 144MHz band open 
all over Europe for hours at a time. This was the event when numerous 
meteors lit up the night sky. It was tremendous. Between 0300-1145UTC 
I made 54 s.s.b. contacts with stations in 20 countries, CT (Portugal), 
DL, EA, F, HA, HB9, I, LA, LY (Lithuania), OE, OH (Finland), 
OM (Slovakia), OK (Czech Republic), OZ (Denmark), SM (Sweden), 
SP (Poland), S5, UA (Russia), YU and 9A. My longest distance contacts 
included the stations of RW1AW (2231km), LY2WR (1884km) and I8MPO
(1829km). 

Signals were reasonably strong during the Leonids shower in 1999 but
nothing like that experienced in the previous year. I was active between 
0130-0430UTC making 14 s.s.b. contacts with stations in 8 countries, EA, 
HA, I, OK, SM, S5, TK (Corsica) and YU. Best DX, but not the furthest, 
was the station of TK5EP who I contacted at 0308UTC. 

In 2000 the meteor activity was very disappointing with only 3 contacts, 
CT1FAK, EA3TI and I3JTQ, being completed between 0300-0400UTC before I 
closed down the station in disgust! 

However meteor activity during the Leonids shower in 2001 was excellent 
with 81 s.s.b. contacts made on the 144MHz band between 0400-1130UTC. 
The shower was exceptional between 0630-0830UTC and during this period 
many bursts lasting minutes at a time were heard giving the impression 
that a Sporadic-E opening was in progress. My tally included stations 
in 17 countries, DL, EA, F, HA, I, LA, LY, OE, OK, OM, SM, S5, TK, 
T9 (Bosnia), US (Ukraine), YU and 9A. Best DX during this shower
were the stations of US5WU (1900km), YU1LA (1898km) and YU7VA (1852km).

Last year 2002 I was active between 0300-1130UTC making 56 s.s.b.
contacts with stations in 17 countries, DL, EA6 (Balearic Islands), ES
(Estonia), HA, I, LA, LY, OE, OH, OH0 (Aland Islands), OK, RX (Russia),
SM,  SP, S5, TK and 9A. Some of the DX stations contacted included
EA6/DL6SAQ (JN20), ES2NA (KO29), HA5OV (JN97), LY2BIL (KO24), OH0JFP
(KP00), OH6MAZ (KP21) and TK5EP (JN41). The top three s.s.b. contacts
were with IK7UXY (2092km), OH7HDU (2133km) and my longest distance ever
via meteor scatter RX1AS (KO59) at 2234km. 

The Leonids shower is certainly a favourite of mine because in just 
six operating periods amounting to 36 hours I've made a total of 235 
s.s.b. meteor scatter contacts with stations in 26 DXCC countries. 
There is no other propagation mode where contacts can be predicted 
with such certainty. 

Peak Activity
So what could happen this year and when will the peak activity occur?
Much of the uncertainty in predicting Leonid storms in the past has been
due to the assumption that the cometary dust was more or less constant
in density, varying from the most dense near the comet and becoming less
and less dense farther away from its orbit and the comet's position in
orbit. However this did not take into account the possibility of stable
dust trails in a similar orbit, trails that could after several
revolutions become quite narrow and dense. The Leonids have been in a
cycle of strong activity up to 2002. Although no storm level activity is
predicted during the next few years it is always possible that
above-normal reflections may be present through to 2006. 

Some predictions calculate that the Earth may encounter an old dust
trail on Thursday November 13 but it is possible that the miss distance
is large enough to negate any observed outburst.  Because unpredicted
events may happen dedicated v.h.f. operators should try to monitor the
Leonids activity between November 13-20 just in case. 

Whatever you decide to do it should be remembered that 2003 is likely 
to be the last time for another 30 years that the Leonids meteor shower 
will put on a show. So get on the v.h.f. bands and make some noise!  

Time to Rise
One aspect that is often overlooked with meteor scatter is that most
(but not all) showers rise and set just like the Moon or Sun. With
moonbounce communication you need to see the Moon to reflect signals to
the other side of the world and it's exactly the same with meteor
scatter contacts. Each shower has different rise and set times and the
meteor stream needs to be well above the horizon before you can use it
for communication purposes. In Europe the shower rises above the horizon
around 2330UTC and sets the following day around 1230UTC. The best times
from the UK for maximum communication efficiency are between 0200 to
1100UTC but if you just want to dabble for the first time I suggest
listening between 0500 to 0800UTC as this is the time when many casual
operators come the band before going to work. If you really want to
maximise your chances I suggest that you go into your shack around
0200UTC on Tuesday November 18 and continue operating for the next 9
hours. 

Narrowband Modes
Meteor scatter contacts are normally accomplished using a narrowband
mode such as c.w. or s.s.b.  Many stations are now using machine
generated modulation (m.g.m.) such as FSK441 and this digital mode can
enable a low power station to produce some quite remarkable results.
However during the peak of the shower when bursts of signals are very
strong and last for many seconds the throughput of s.s.b. voice is
infinitely more efficient. With FSK441 you are forced to use 1-minute
periods and the minimum time required to complete a contact will be five
minutes if everything runs to plan. High speed morse contacts with
standardised 2.5 minutes periods are even worse and the minimum time to
complete is 12.5 minutes. On the other hand an s.s.b. contact using the
correct break procedure may be completed within 15 seconds and it's not
unheard of to make four or five contacts in one minute during a good
burst. In my opinion it's best to follow the laid down IARU Region 1
meteor scatter procedures and these can be found in various VHF
handbooks or on the Internet. However if the shower is really good it
may be possible to dispense with convention and make quick s.s.b.
exchanges using traditional signal reporting methods. 

VHF Bands
Contacts can easily be made on the 50MHz, 70MHz and 144MHz bands
although I really recommend operating on the 144MHz band as this is
where all the 'real' DX activity is located. Although you may be able to
make contacts with low power it can be a bit frustrating. Medium power
50-100W will give good results especially if coupled with a good antenna
and low-loss feeder cable. A horizontally mounted Yagi antenna of
between 8 to 16-elements will be sufficient but it will be useful to be
able to rotate it towards selected activity areas throughout Europe. 

Now tune your receiver to the s.s.b. meteor scatter calling frequency
144.200MHz. Listen to the operating practices of the more experienced
stations before you get going but don't stay on 144.200MHz all the time.
Spread out around the s.s.b. sub-band. When a burst occurs other
stations will find you. You may even hear activity on the national
calling frequency 144.300MHz. Use clear unambiguous phonetics. Make
rapid exchanges, call signs and reports are all you need. Try to keep
individual exchanges to around 5 seconds and a complete QSO in less than
15 seconds.

73
David G4ASR
(I'll be active on 144MHz with SSB & HSCW but *NOT* FSK441!)