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(meteorobs) Observation Aug 11/12 1999
Hi everyone,
On the evening of Wednesday August 11th, weather conditions did not
look too promising for Ottawa, with a forecast calling for mainly
cloudy. After some debate, I decided to take a chance and go out
anyway. I went for a one hour drive out south-west of Ottawa to a
friend's observatory near Perth. About halfway there, I began to
seriously question the weather as the sky was completely overcast
with occasional drops of rain. Once there, I was greeted by an
optimistic Mike Wirths saying that the weather was on a clearing
trend. I looked up into the west to see that patches of blue sky were
indeed forming. We then checked the latest satellite imagery, and to
my amazement, it showed a large clear hole approaching with clouds
dissipating quickly. Indeed, within a few minutes the sky cleared up
completely and remained that way all night.
Early earthgrazing Perseids first appeared in deep twilight, as I was
getting ready to start. One of them was a nice orange magnitude -4
that travelled close to Ursa Major with over 30 degrees lenght. A few
minutes later, another long Perseid of about magnitude -3 went high
overhead. I signed on at 2:25 UT to observe for 6 hours time. Not
long after I began, patchy ground level fog formed and resulted with
reduced limiting magnitude of 6.2. Eventually, as the night went on,
the fog cleared and the sky gradually rose to 6.5 for the final hour.
In all, a total of 250 meteors were seen. The first hour had low
rates with only 15 meteors (only 8 of those being Perseids (PER). As
the PER radiant rose higher and fog cleared, meteors gradually picked
up with 19 PER for the second hour, 27 PER for the third and 38 PER
for the fourth. The fifth hour had similar activity, but my final
hour surged to 49 PER. Activity also present in small numbers from
the Aquarids radiants (SDA,NDA,NIA) and Alpha Capricornids (CAP).
Only one Kappa Cygnid (KCG) was seen. Sporadics produced at best 15
meteors in a single hour.
There were a few good "highlights of the night". The most impressive
sight was seeing two meteors nearly crossing paths! One was a fast
magn +3 Perseid in the north, and at the same time, a magn +3
sporadic sliced through on a 90 degree angle, "barely" missing each
other! At 6:58 UT, another PER and SPO appeared simultaneously, this
time both meteors quite far apart. There were 4 more instances of two
meteors appearing within a second. Long meteors were also beautiful.
Two Perseids were seen travelling long 40 degrees path. One of these
earthgrazer had a magnitude -3, vibrant blue-white color and left
behind a 9 second persistent train. During the final hour before
dawn, another magnitude -3 blue-white PER appeared, this time
producing a terminal burst and leaving behind 8 sec.train. As morning
twilight grew, I signed off at 8:40 UT. Before leaving back home, we
enjoyed viewing the planets under good seeing with Mike's 25inch
telescope. I also ran a 50mm f2 camera on tripod for most of the
night, and might have captured one or two Perseids. It was the most
dewy night in my memory, as everything got awfully wet in the
morning. However, a really enjoyable night.
DATE: August 11/12 1999
BEGIN: 2:25 UT (22:25 EDT) END: 8:40 UT (4:40 EDT)
OBSERVER: Pierre Martin (MARPI)
LOCATION: Long: -76.307 West; Lat: 44.820 North Elevation:100m
City & Province: Perth, Ontario, CANADA
RECORDING METHOD: talking clock/tape recorder
-----------------------------------------------------------------------
OBSERVED SHOWERS: 3-letter code; radiant position
PER (Perseids) 03h00 +59
KCG (Kappa Cygnids) 19h00 +57
UPG (Upsilon Pegasids) 23h15 +17
NIA (N. Iota Aquarids (anthelion) 22h40 -09
NDA (N. Delta Aquarids) 22h30 -06
SDA (S. Delta Aquarids) 23h20 -14
CAP (Alpha Capricornids) 21h10 -05
PAU (Pisces Austrinids) 23h40 -27
-----------------------------------------------------------------------
OBSERVING PERIODS: 0 = none seen;
PERIOD(UT) FIELD Teff F LM SPO PER NDA SDA CAP NIA KCG
2:25-3:25 SE70 1.00 1.00 6.18 6 8 0 0 1 0 0
3:25-4:19 " 0.90 " 6.22 11 19 0 1 0 0 1
4:22-5:23 SE60 1.01 " 6.35 9 27 1 0 0 1 0
5:23-6:30 " 1.00 " 6.45 11 38 1 0 1 0 0
6:30-7:31 " 1.00 " 6.50 15 37 1 1 0 0 0
7:31-8:40 " 1.14 " 6.38 11 49 0 0 0 0 0
----------------------------------------------------------------------------
TOTALS: 6.05 63 178 3 2 2 1 1 = 250
----------------------------------------------------------------------------
MAGNITUDE DISTRIBUTIONS:
SHOWER -3 -2 -1 0 +1 +2 +3 +4 +5 +6 AVERAGE
SPO 0 0 0 0 0 6 16 24 16 1 +3.8
PER 2 2 4 3 3 35 52 46 26 5 +3.1
NDA 0 0 0 0 0 0 2 1 0 0 +3.3
SDA 0 0 0 0 0 0 0 1 1 0 +4.5
CAP 0 0 0 0 0 0 1 0 1 0 +4.0
NIA 0 0 0 0 0 0 0 0 1 0 +5.0
KCG 0 0 0 0 0 0 0 1 0 0 +4.0
---------------------------------------------
TOTALS: 2 2 4 3 3 41 71 73 45 6
---------------------------------------------
SKY OBSCURED: none
------------------
Total dead time: 9 minutes (breaks)
Breaks: 4:19-4:22, 4:28(0.5 min), 5:38-5:44, 6:12-6:13, 6:36(0.5 min),
7:05(0.5 min), 8:06(0.5 min)
---------------------------------------------------------------------
REMARKS
Some evening ground level fog patches, dissipating gradually later on.
3:25 UT; FOV at SE80 for 15 minutes
5:18 UT; FOV at NE70 for 15 minutes
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