(meteorobs) Geminids II - Dec 10/11
Bruce McCurdy
bmccurdy at telusplanet.net
Mon Dec 17 01:56:36 EST 2007
My observing buddy slash weather guru Alister Ling spoke to me at the
RASC meeting on Monday December 10 and suggested that it would stay clear
for a few more hours that night, then Tue/Wed, Wed/Thu and probably even the
peak night of Thu/Fri would be a write-off. So I decided to head out to the
Blackfoot observing site in the Beaver Hills Dark Sky Preserve after the
post-meeting meeting, enjoying the fellowship at the pub while holding off
on the usual libation before heading out at midnight, alone.
I settled in to count at 1 a.m. MST, and logged a very good three hours
of Teff, logging 76 meteors including 31 Geminids. All but two of the GEMs
were no brighter than mag +2, although I had a decent number of bright
meteors from other radiants. The visual show was pretty tame compared to
the radio activity, which was quite intense. For the first time in awhile I
monitored forward scatter. In the ever more packed radio universe my old FM
frequency of 92.1 had constant sideband bleeding, but I found very clean
static and excellent reception on FM 94.5. I consistently averaged 2 or 3
"hits" per minute throughout the night. At one point on my audiotape there
were 7 hits in about 45 seconds, unfortunately not one of them had a visual
counterpart. It was interesting to hear the wide variety of musical genres
which indicated a number of different transmitters were engaged. One
bright -3 sigma Hydrid prompted a 30-second radio burst that started with a
raucous rocker by Deep Purple, was lost to interference for a split second
before cycling back in with the country supergroup the Notorious Cherry
Bombs. If you'll forgive an "on-colour" joke, that meteor medley from Purple
to Cherry pretty much covered the popular music spectrum. And yes, it's
possible to giggle like an idiot while all alone in -20° C. temperatures at
three o'clock in the morning.
With a good first hour under my belt I took a half-hour binocular break
to drink in the spectacular winter sky. What a sight-seeing tour it was,
from Sirius through Orion's Belt to the Hyades and Pleiades and on up into
Perseus for Comet Holmes and the Double Cluster; then back down the Milky
Way through the alpha Persei Association, the clusters of southern Auriga
and Gemini and on to brilliant Mars and the Twins. After enjoying these
marvels of astronomy I took a few minutes to admire a marvel of physics, a
very nice display of the Aurora Borealis demonstrating complex interlacing
magnetic field lines and pale shades of green. Thankfully it held
steadfastly to the northeast throughout, so I turned back to the south where
the only action in the upper atmosphere involved that marvel of physics
*and* astronomy known as meteors. I spent much of the rest of the night
repeating the same grand sweep across the winter sky with the naked eye,
trolling for meteors all the while.
I wound up enjoying myself so thoroughly I stayed for an unplanned third
hour, which featured a number of possible December Leo Minorids. This
radiant came to my attention after the fact through Bob Lunsford's
outstanding Mojave Desert reports. For whatever reason, they were not
included in Bob's own weekly outlooks, nor in the IMO calendar. Since I use
Bob's outlooks as my guide to active radiants, I wasn't looking for DLMs,
however in that last hour I spotted a number of "sporadics" emanating from
that general area, to the point I was making remarks on my tape about a
possible radiant to the north of Leo. Reconciling my taped descriptions to
this radiant after the fact, there were as many as seven candidates.
Just minutes before reluctantly calling it a night, I was rewarded with
my best meteor of the session, a coppery-orange sporadic with an explosion
point that I adjudged to be mag -4. It was the exclamation point that
punctuated a wonderful night.
Bruce
*****
Observer: Bruce McCurdy, MCCBR
Location: Beaver Hills Dark Sky Preserve (Blackfoot), IMO location code
51128,
53° 32' 12" N., 112° 46' 48" W., elevation 711 metres
Date: 2007 December 11, 08:00-11:40 UT; Teff = 3.0 hours
Limiting magnitude = 5.3 to 5.5 (SQM = ~20.0)
Primary method: visual, microscassette recorder and talking watch
Secondary method: audio, monitoring forward scatter by car radio (FM 94.5)
Comments in "quotations" are verbatim transcripts
/ = description of meteor in length and duration
~ = description of persistent train in length and duration
SRB = simultaneous radio burst heard with observed meteor
Active radiants:
Antihelion (ANT) 05:56 (089) +23
Monocerotids (MON) 06:36 (099) +08
Geminids (GEM) 07:08 (107) +33
Sigma Hydrids (HYD) 08:20 (125) +02
Coma Berenicids (COM) 11:16 (169) +27
08:00 - 09:00; clear; avg. LM = 5.6; facing south 60°; Teff = 1.0 hour
Time type mag comment
----------------------------------
08:00 start
08:01 GEM -1 SRB
08:04 ANT +3 slow, near radiant
08:04 ANT +4
08:06 GEM +5
08:07 GEM +4
08:10 SPO +2
08:13 GEM +5
08:16 GEM +3
08:28 MON +4 SRB
08:30 SPO +3
08:31 GEM +2
08:33 HYD +4 / 0.5 s
08:37 ANT 0 / 10°, brief wake
08:38 GEM +4
08:39 SPO +3 SRB
08:41 COM -2 ~0.5 s, 10°, nice wake
08:45 SPO -2 v slow, / 0.5 s, 4°
08:48 ANT +4
08:48 GEM +3 creamy coloured
08:52 SPO +5
08:54 SPO +4
***
4 ANT: 0, +3, +4(2)
1 MON: +4
8 GEM: -1, +2, +3, +4(3), +5(2)
1 HYD: +4
1 COM: -2
8 SPO: -2, +2, +3(3), +4, +5(2)
Total meteors: twenty-three
*****
09:00-09:30 break
09:30 - 10:30; clear; avg. LM = 5.8; facing south 60°; Teff = 1.0 hour
Time type mag comment
----------------------------------
09:30 restart
09:31 SPO +3
09:36 SPO -2 coppery-orange, ~1.0 s, "between Mars and Sirius and
brighter than both"
09:37 COM 0 SRB, ~0.5 s
09:41 HYD +3 / 1 s, 8°; ~0.5 s; "I love the slow ones"
09:43 GEM +4
09:44 SPO +2 "Just coming out of Leo Minor", possible DLM
09:45 GEM +4
09:47 SPO 0
09:48 GEM +5 SRB, "sounded like the Microsoft Chord of Error"
09:50 COM +1 SRB
09:55 HYD -1 /1s, ~0.5 s, broad coma
09:57 GEM +3
10:02 GEM +5
10:02 COM +2
10:04 SPO +3
10:07 GEM +2 SRB
10:07 GEM +5 SRB
10:07 HYD -3 SRB (~30 s), multiple transmitters; pure white,
explosion point followed by break-up
10:11 SPO +4
10:18 SPO +1 SRB (~5 s)
10:20 COM +3 / short, near radiant; "gave impression of being fast,
like a line drive hit right at me"
10:20 SPO +4
10:25 GEM +3 creamy white
10:25 HYD +1 ~0.5 s, white
10:26 GEM +3 SRB
10:28 GEM +4 / 2°, near radiant
***
10 GEM: +2, +3(3), +4(3), +5(3)
4 HYD: -3, -1, +1, +3
4 COM: 0, +1, +2, +3
9 SPO: -2, 0, +1, +2, +3(3), +4(2)
(inc 1 suspected DLM, +2)
Total meteors: twenty-seven
*****
10:30 - 10:40 break
10:40 - 11:40; clear; avg. LM = 5.7; facing south 60°; Teff = 1.0 hour
Time type mag comment
----------------------------------
10:41 GEM +4
10:43 SPO +4 DLM?
10:43 GEM +4
10:47 SPO +4 DLM?
10:49 SPO +4 DLM?
10:49 GEM +3
10:52 GEM +2
10:54 SPO +3 DLM? (4 suspects in 11 minutes)
Light cloud cover, SQM dropped from 20.8 to 20.5
11:02 SPO +2
11:06 SPO +4 SRB; DLM?
11:08 GEM +1 SRB
11:08 SPO -1 SRB; ~ 1 s; white
11:12 GEM +2 / short, near radiant
11:13 GEM +3 SRB
11:14 SPO -1 SRB, DLM? (6 suspects in 31 minutes)
11:14 GEM +4
11:16 COM 0 brief wake
11:18 GEM +4
11:26 SPO +4
11:33 GEM +3
11:33 SPO -4 "like a rocket burn -- bright head w. contrail, slow,
deeply copper-orange"
11:34 GEM +3
11:34 GEM +2
11:38 SPO +3 SRB
11:40 HYD +2
11:40 GEM +2
11:40 end
***
13 GEM: +1, +2(4), +3(4), +4(4)
1 HYD: +2
1 COM: 0
11 SPO: -4, -1(2), +2, +3(2), +4(5)
(inc. 6 suspected DLM, -1, +3, +4(4)
Total meteors: twenty-six
*****
Observing summary
Teff = 3.0 hours
4 ANT: 0, +3, +4(2)
[avg. = +2.7]
1 MON: +4
[avg. = +4]
31 GEM: -1, +1, +2(6), +3(8), +4(10), +5(5) [avg.
= +3.3]
6 HYD: -3, -1, +1, +2, +3, +4
[avg. = +1.0]
6 COM: -2, 0(2), +1, +2, +3
[avg. = +0.7]
28 SPO: -4, -2(2), -1(2), 0, +1, +2(3), +3(8), +4(8), +5(2) [avg. =
+2.3]
(inc. 7 suspected DLM, -1, +2, +3, +4(4) [avg. = +2.9] )
Total meteors: seventy-six
*****
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