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(meteorobs) FWD from IMO-NEWS: Perseid outburst on radio




Old news perhaps, but I feel responsible... ;>

Lew


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Date: Tue, 13 Aug 1996 14:50:42 +0200
From: tonsch@ksw.rugdot nl (Ton Schoenmaker - Kapteyn Sterrenwacht Roden)
To: imo-news@tu-chemnitzdot de
Subject: Perseid outburst on radio
X-Vms-To: SMTP%"imo-news@tu-chemnitzdot de@astro.rugdot nl"
X-Vms-Cc: TONSCH


Preliminary report on radio observations of the Perseids 1996

Extensive obervations were made to monitor forward scatter signals
from a FM broadcasting station in Krakow, Poland. The transmitter
emits on 66.89 MHz with a power of 120 kW. The signals were received
using a 5 element Yagi, pointing at an azimuth of 100 degrees with
an elevation of 15 degrees.
Observations started 8 August for severals hours per day, but from
10 August covering 24 hours per day. The signals were registered with
a pen recorder with a paper speed of 9 or 18 inch per hour (depending
on the time of the day). To avoid fake signals, a threshold for counting
was set at such a level that during afternoon, the daily minimum, about
40 meteors per hour were counted. The total number of reflections actually
recorded during minimum was about 120 per hour. During daily maximum these
numbers were about 3 to 4 times larger.
The observations were sometimes interrupted by thunder-storms. Also
there were some interruptions caused by special atmospheric conditions,
which gave continuous reception of the Polish transmitter. Luckily
such periods never exceeded 30 minutes.
During 11/12 August at 23h30m UT the number of "bright" meteors started
to rise, with a maximum around 01h00m UT. A very bright meteor appeared
at 01h04m10s wich gave a high signal for nearly 3 minutes. At that time
probably the same meteor was seen by eye through clouds. It was a bright
flash at 70 degrees in the East. During maximum activity it is difficult
to count the number of meteors, because of the large number of long
reflections, which mask the weaker signals. At 2h15m UT the wildest part
was over, but there were smaller peaks at around 3h30m and 5h30m UT.
Of course the observability function has to applied to the raw counts,
but the correction factors are uncertain, especially for the time
the transmitter and radiant are in nearly the same direction (in my case
about 5h UT).
During the rest of 12 August there was no extreme activity. The count
levels were nearly the same as on 10 and 11 August. To convert
the recorder strips into numbers will be a difficult task for the
period around the peak. Maybe it is best to measure the duration of the
signal above the threshold as defined above. But one strong meteor could
give very much weight then. Anyone suggestions how to evaluate these
recordings?
A more detailed report will be sent to Chris Steyaert in Belgium and
be published (hopefully) in the Radio Meteor Obs. Bulletin of next
month.
Best regards,
                                           Ton Schoenmaker, PA0EFA
                                           Roden, Netherlands
                                           tonsch@ksw.rugdot nl

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