(meteorobs) Mojave Geminids Day 2 (Dec 13/14)
Robert Lunsford
lunro.imo.usa at cox.net
Mon Dec 17 01:29:04 EST 2007
After a nice nap in the bed of the truck I woke near 9am Thursday to nearly
totally overcast skies and temperatures in the mid-forties. The only blue
sky was a strip along the northwest horizon. Systems here normally move
northwest to southeast so I was hoping this clear strip would widen.
Unfortunately the clouds were moving very slowly and by noon the sky was
just as bad as it was three hours earlier. I was surprised to find ice on
the tailgate of my truck where my jug of water had leaked. The grooves in
the bed liner filled with water and then froze in the sub-freezing
temperatures during the morning.
That afternoon Robin and I basically just sat around and discussed various
topics ranging from American politics to the current state of meteor
observing both here and abroad. Robin is considering attending the 2008 IMC
which would make him the first American attend. It was nice to talk face to
face for a change. I just wish more of us could get together for such
visits!
The afternoon temperature peaked at 61F (16C), still under mostly cloudy
skies. At times the western sky would clear only to have other clouds fill
in. It wasn't until 3pm that we began to have hope that we would see
something after the sun set. At that time the western sky was mostly clear
and the clouds in the east seemed to be departing.
By sunset only a strip of clouds in the east obscured the sky. As soon as it
became dark we built a campfire and had dinner. At 6pm we started watching
for Geminid earthgrazers with our backs to the campfires to keep our
backsides warm and to keep our night vision somewhat intact. I was facing
low in the southeast and Robin low in the northeast. At approximately 6:15
Robin caught the first one, a blue, zero magnitude beauty that shot below
Polaris and on into Draco toward Vega. It lasted long enough for me to turn
around and catch the last second of flight. The next two appeared on my side
but were faint and fairly short. Both of them shot through the shield of
Orion. The last and strangest earthgrazer was first seen by Robin over the
light dome of Las Vegas. It was a short meteor that lasted four seconds,
apparently an earthgrazer headed in our direction. It was the same magnitude
and color of Mars, which was a deep orange so low to the horizon. I caught
most of it as it occurred near the edge of my field of view.
After 45 minutes we tired of standing and thought we should catch a nap
before observing. While watching for earthgrazers we noticed how easy comet
Holmes appeared despite the crescent moon. We both took a look at it though
my 9.25in SCT before retiring. It more than filled the FOV in my telescope
and was actually a better sight through binoculars and the small finder
scope.
We both retired around 7:30pm, planning to start observing at 11pm. It was a
restless sleep and luckily I caught a
-5 Geminid fireball at 8:05 shooting into Aquarius. I woke again at 9:30 and
the sky was perfect and full of Geminids. I jumped out of the truck and set
up to observe. I started the intensified video recorder at a quarter till
the hour and I began counting two minutes later. The beginning temperature
was 34F (1C) and humidity of 66%. the estimated limiting magnitude was +6.5.
I faced southward just west of Orion.
Despite the early hour the meteors were falling in bunches. None for a
minute or two then a handful all at once. Most of the minutes that produced
meteors had multiple Geminids. During the first hour I counted 78 meteors,
69 of them were Geminids. All other meteors that hour were sporadic except
for a lone Monocerotid. Most of the Geminids seen during this hour were on
the faint side with many +3's and +4's, a few +5's and even a couple +6's.
The brightest was a -1 seen near the end of the period.
The second hour (1045-1145pm PST) produced 86 meteors with 80 of them being
Geminids. Very few sporadics were seen this hour. A couple of antihelions
appeared along with a Sigma Hydrid. The Geminids were slightly brighter with
the brightest being a pair of -2's.
The third hour (1145-1245am PST) produced 117 meteors with 102 of them being
Geminids. The first COM's appeared during this hour and there was also a
good representation of the other minor showers this hour. The brightest
Geminids were a pair of -3's one of them producing a rare Geminid train.
The fourth hour (1245-145am PST) saw a drop in activity as I counted 88
meteors. This period should have produced the peak activity. I believe Robin
also suffered a dip in activity during this time but I am not 100% certain.
It will be interesting to see the video results for this period. Of the 88
meteors, 72 were Geminids. The brightest meteors during this period was a
trio of -2's. A majority of these bright meteors were gold to orange in
color.
Rates were back up for the fifth hour (145-245am PST) as 115 meteors were
counted with 95 of them being Geminids. It was during this hour the first
of several December Leo Minorids (DLM) were spotted. Four COM's were also
seen along with a least one representative of all the other active minor
radiants. The brightest Geminid during this period was a -3.
The sixth hour (245-345am PST) produced 117 meteors with 97 of them being
Geminids. The most impressive meteor of the night occurred during this
period. At 3:44 an estimated -7 Geminid shot overhead and eastward into Leo.
It was an electric blue color with a wide coma. It also produced a
persistent train that lasted for two seconds. Unfortunately the video
recorder was aimed a bit lower in the sky and missed this meteor. Three more
COM's were also seen this hour.
The seventh hour (345-445am PST) saw a significant drop in activity with 77
meteors being recorded. The Geminid count for this hour was 59 with no
meteor brighter than zero magnitude. 3 COM's and 2 DLM's were also spotted
this hour.
The last hour (445-545am PST) produced 54 meteors with 44 of them being
Geminids. The sky was very bright during the last 15 minutes and I probably
should have quit a bit earlier. By this time my back was killing me as I was
using a cheap plastic lawn chair. Despite two sleeping bags and a blanket by
this time I felt like a popsicle. The ending temperature was 25F (-4C) with
a humidity of 88%. The minor shower highlight for this hour was 2 more
DLM's.
The final totals for the night were 732 meteors, 618 GEM's, 11 ANT's, 12
COM's, 6 DLM's, 7 HYD's, 9 MON's, 69 SPO's
I don't recall a night that had so many simultaneous meteors, except for the
recent Leonid storms. They truly came in two's and three's. I was often
logging two meteors into the recorder while two more occurred. I also saw
at least five Geminid trains which is more than I ever recall in a single
night. I also checked out Mars and Saturn before retiring but the seeing was
poor so I did not spend much time looking through the scope.
Bob Lunsford
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