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(meteorobs) 11/17/97 Leonids at Poplar Springs

Hello folks,

Last night proved to be one of the most fascinating sessions I have ever
spent monitoring radiometeor activity.  Here is a log of events:


2330 CST / 0530 UT -

I began the session with low level sporadic meteor activity, and very light
tropospheric scatter signals in the background.  

0100 CST / 0700 UT - 

An occasional Leonid meteor echo can now be distinguished from the others
due to the very fast meteor head-echo, high returned power, and quite long
durations; generally between 10 and 60 seconds.  The rate is noticeably
higher than the same time on the previous night, and the population is
skewed more toward the "brighter" end of the spectrum as well.

0200 CST / 0800 UT - 

The rate of distinguishable Leonid echoes continues to increase markedly,
with some now reaching two minutes in furation.  This night so far looks
very similar the 1996 peak activity, especially with the high numbers of
strong overdense events.

0330 CST / 0930 UT - 

The Leonid rate begins to pick up, with overdense events now tending to
"cluster" together.  One to three events may overlap with each other,
causing 5 to 8 minutes of nearly continuous signal.

0400 CST / 1000 UT - 

My wife, Lisa, goes out with me to check on the visual activity.  The moon
is shining brightly, high and to the west, with high cirrus clouds causing
the stars to be somewhat hazy.  In 15-20 minutes she spots only 1 Leonid,
moderately bright and near the radiant.  Although the radio system "looks
at" an area much larger than what my wife can see (which is far to the
northeast from us) I still expected the rate to be much better -- even with
the moon.  Lisa goes back inside to the heater, and I go back to the radio
system.

0430 CST / 1030 UT - 

The Leonids are banging in quite impressively now.  There is so much
overlap between these long events that the meteor head-echo from an
incoming event can sound garbled or distorted as it mixes with the events
in the background.

0500 CST / 1100 UT - 

Lisa and I go out again to spot what can be seen, but again we comeback
disappointed.  Morning twilight is now combining with the haze overhead to
dampen the view further.  It amazes me that the radio system shows one
bright Leonid after another while our morning sky is quite docile.

0630 CST / 1230 UT - 

Combining morning sporadics and Leonids together, the radio becomes a
continuous din of activity.  Some light ES is also evident now.

The activity reminds me of a radio account of the 1946 Giacobinids, in
which the meteor activity essentially created a continuous layer of
electrons, blending all incoming meteor events together in one long event.  

Only the strongest events can be picked out individually by ear, while the
computer sees a rapidly fluctuating, continuous signal.

0730 CST / 1330 UT - 

The sun is up and shining brightly, while the din continues on the radio.
Garbled meteor head-echoes can again be heard as the radiant begins to drop
in the west -- something which is not expected, since the forward-scatter
link bearing is less perpindicular to the setting radiant than to the
rising radiant.

0950 CST / 1550 UT -

The activity is letting up some as the radiant drops in altitude.  It is
still quite strong, with some light ES mixed in with the meteor activity.
Head-echoes can still occasionally be heard, and some events continue to
last up to 2 to 3 minutes.  


overall, this morning's Leonids were a good bit better than the show last
year.  The tendency towards the bright end was again quite evident, which I
did not expect over the eastern USA.  

It is also obvious that the duration and power enhancements caused by
forward-scatter (as compared to back-scatter) would make monitoring actual
storm conditions from this shower quite difficult using this system, due to
the "overlapping" effect described above.  A higher operating frequency and
shorter range would help to counteract this.

Take care,  all,

     Jim


James Richardson
Graceville, Florida
richardson@digitalexp.com

Operations Manager / Radiometeor Project Coordinator
American Meteor Society (AMS)
http://www.serve.com/meteors/
References: