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(meteorobs) IMO-NEWS: mag -12 bolide Udine/Italy, Aug.12, 21:49:14h UT


>Date: Tue, 15 Sep 1998 19:41:33 +0200 (MET DST)
>To: imo-news@imodot net
>From: "W. Kuneth" <kuneth@netway.at>
>Subject: mag -12 bolide Udine/Italy, Aug.12, 21:49:14h UT

The mag -12 fireball from Aug 12, 1998 at 21h49m14s UT:

On the evening of Aug 12 there was a public observation initiated by the
Associazione Friulana di Astronomia e Meteorologia (AFAM) at the club=B4s
observatory in Remanzacco near Udine/Italy. The sky was clear with some 100
people watching for Perseids, the amplified sound of the forward meteor
scatter system was amplified outside for simultanious listening to the radio
echos, when a big fireball crossed the sky:
--------------------
...we are glad to announce you that at 21.49.30 UT a meteor
was seen over our sky, with a strong related signal on the DSP FFT
device. (a very long meteor with green-blue colour, from Pegasus to Vega,=
 seen
by dozen of people who listened also to the amplified sound)
---------------------
.... the correct timing, the starting time should be: 23h49m14s +/-2s (local
time)
---------------------
starting point (approx) A.R. 21h Decl.+10=B0 23h59m14s local time
ending point  (approx) A.R. 18h Decl.+50=B0
---------------------
This was later "exactified" to:
Starting point: RA: 21h30'  Decl: 5 deg
End Point: RA: 18h 30' Decl 45 deg.
Magnitude: -12
Meteor travel duration: 5 seconds
Bright glowing trail after the meteor for 60 degrees.
Trail duration 10 seconds.
Speed described as "medium"
(Official information from Giorgio Bressan, AFAM)
----------------------
...the event was really terrific, all the media are reporting on it,
even professional astronomers have been asked for comments...
---------------------
...I heard a crackling sound at the same time when the meteor was visible,
despite all the croud screaming "OOOOOOoooooohhhh". All around me seemed to
have heard this crackling sound, too, maybe some did not, it seemed to by
quite normal to hear that sound.
-----------------------------
.dot it looked like a flame crossing the sky..
-----------------------------
..the meteor was also seen at many other places in italy one report was from
Napoli, Italy (400 km to south).
-----------------------------
dot it was going from southeast to northwest, and was no Perseid.
-----------------------------
.. magnitude estimation is in the range of -12/-14; (was later set to -12)
it took about 5-6 seconds to cross a 60 degrees arc, from Aquila to Lyra
where, after a bright flash, the body disappeared, no solid residuals have
been reported to date. Some low amplitude bang has been reported but the
uncertainty is hight. Visual extention of the bright core has been reported
1,5 time the full moon size. Colours where visually recorded changing from
blu to green
while the final phase became red.
-----------------------------
....The center of the meteor appeared yellow, with the trail white, others
have seen the brightest part as green...
---------------------------
...yes, we have recorded the radio echo of the fireball on 4 different
forward scatter path=B4s with a echo duration of up to 25 seconds, one with=
 a
good meteor head echo at the start of the echo. The object did not break up
on the entry, but burned up as a solid object, there is no "fragmentation"
visible, so the meteor seems not of cometary origin. =20
---------------------
>From the FFTDSP radio meteor recordings (1) at 53.760 Mhz in Remanzacco,
Udine the speed was determined by measuring the head-echo (2) as follows:

The meteor speed is 17.5 (+/-2.5) km/sec.=20

(1) FFTDSP software by AF9Y, see http://www.webcom.com/~af9y/
(2) "Radio doppler effect for forward-scatter meteor head echos" by J.
Richardson and W. Kuneth, WGN 26-3, 1996, pp 117-130.
----------------------------
All reports above are from members of the Radio Astronomy Group of AFAM.