(meteorobs) Terrific night of Geminids in central Alberta
Kim Youmans
meteorsga at bellsouth.net
Mon Dec 17 09:20:49 EST 2012
"But as of now I no longer feel even slightly unlucky, as one is fortunate to
have one night such as this in a year."
Way to go, Bruce! Up until friday morning, I was feeling lucky to see a handful
of meteors all year long. :)
Kim Y.
________________________________
From: Bruce McCurdy <bmccurdy at shaw.ca>
To: Global Meteor Observing Forum <meteorobs at meteorobs.org>; Astronomy
Discussion list <astro at mailman.srv.ualberta.ca>
Sent: Mon, December 17, 2012 6:10:29 AM
Subject: Re: (meteorobs) Terrific night of Geminids in central Alberta
Finally got around to transcribing my results from my observing session on the
Geminids pre-peak night, 2012 Dec 12-13. I got 3.00 hours Teff between 08:52 and
11:59 UT (about two to five o’clock local time = MST). It probably took me
longer in real time to transcribe my audio tape, tote up the results, and submit
my report to IMO than I actually spent under the stars!
That’s a price I’m prepared to pay for a night that includes a couple hundred
meteors, as Thursday morning did. Turns out I pretty much nailed it right after
I got home when I gave this preliminary report to the MeteorObs list:
“I got just over 100 recordings and I’d be surprised if my average was much less
than two meteors per recording. In fact, I’ll take the “over”. They were
happening in bunches all night, with some interesting cases of simultaneous
meteors or nearly so (where the second one started before the first was done). A
few fireballs in the mix.”
So I had to laugh when my 102 recordings turned out to contain 205 meteors, for
an average of 2.01 meteors per recording. I’ll take the “over”, indeed!
169 of those were Geminids, of an average magnitude of +1.9 with hourly counts
of 57, 61 and 51. I also saw members of five other showers, including a couple
of very late (suspected) North Taurids. I know their season is deemed to end
around Dec 10, and if that’s an absolute date I guess I saw a couple of
sporadics masquerading as North Taurids. But my best guess is that I happened to
catch a couple of outliers.
The clumping was apparent from my first entry (literally, three meteors within
ten seconds of my turning on the voice recorder to start my session) to the last
(four within 20 seconds). Such is standard fare on meteor-rich nights and is
surely random distribution for the most part, although there were a couple of
cases of meteors that appeared to be related. On this night of plentiful meteors
I had four cases where two meteors were visible at once, including two instances
that were exactly simultaneous at both beginning and end points.
One of these events was a pair of Gems of mags +3 and +4 that straddled Orion,
plummeting to either side of the Hunter. The other was especially interesting, a
closely matched pair of short meteors very near the sigma Hydrid radiant, from
which they were heading to crudely nine and ten o’clock position angles. They
appeared exactly at the same moment, one (just) above the other, and diverged
slightly as they headed east and away from the radiant, which was exceedingly
well-defined at that moment! By the end of their path they were still within 1°
of each other. They were pretty much identical twins, both judged at mag 3, as
close to equals as cat’s eye double stars like Porrima or Mesarthim appear in a
telescope. But with the added element of duration; the simultaneity was
essentially perfect. I have never quite seen the like. Is there such a thing as
a split meteoroid?
Another interesting duo was mismatched, a zeroeth magnitude Geminid and a second
mag December Leo Minorid at roughly 90° angles to each other nearly crossing
swords down below both radiants (and between the two in RA). The DLM was a split
second “late” for its appointment or that would have happened.
In all I had 31 negative magnitude meteors, 29 of these Geminids. Of the six
that were mag -3 or brighter -- Jupiter was a very handy comparison star on this
night! -- four occurred in the last half hour. Brightest of all was adjudged to
be -6, with a deep, almost burnt orange hue and a brilliant flashpoint. The -5 I
saw was also in the red part of the spectrum, but otherwise the predominant
colour was green to blue-green, with about six examples. Mostly they were white
or nearly so, with few persistent trains as is normal for the Gems.
I faced south throughout, even as the Geminid radiant crested fairly early in my
session and thereafter the bright stars of the Winter Hexagon began to dip
towards the sky glow of the city in the west. I opted not to do any sort of FM
radio monitoring, but instead enjoyed the profound silence of the December
overnight. In the middle hour there were very few vehicles on the main highway 4
km to the north, so even the low end hum was all but gone. The coyotes were
around but never kicked it into gear, and I never heard a bird at any time, not
even an owl. The only startling noise: a couple of loudish staccato notes that
reminded me of the crack of a baseball bat, but which surely were the cracking
of ice! It was a cold enough night with the temperature ranging from -17 to -20
C, and ice fog that reflected the snow and whitened the horizons in all
directions even as I never saw a wisp of cloud all night. Despite it being New
Moon my limiting magnitude was only 5.9, but what a treat that was after having
been confined to the city.
Indeed this was my first meteor session since the (also-good) Perseids, after
being skunked for all of the Orionids, Taurids, and Leonids this fall. But as of
now I no longer feel even slightly unlucky, as one is fortunate to have one
night such as this in a year.
Bruce
*****
PS: IMO observing summary here:
http://vmo.imo.net/imozhr/obsview/view.php?id=11605
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