(meteorobs) Moondust

[Bruce McCurdy]

    [Part One: Visual Anecdote]

   The moral of this story is "if you're going to observe Geminids on an 
off-peak night, try to make sure it's *before* the peak."

    Never have those words been truer than this year, when that fickle 
mistress Moon grew increasingly obnoxious from night to night. I did a 
little pre-peak observing on Sunday morning from my backyard (described 
previously but of no scientific value). Clouds than prevailed for the most 
part. By last night the brilliant Full Moon soared high above the ecliptic 
in northern Taurus near El Nath, and was high in the sky throughout the long 
hours of astronomical darkness. Furthermore, Luna is near the peak of her 
19-year cycle, so a winter solstice Full Moon just now is about as far north 
as it can ever get; last night it was cresting high above the ecliptic 
defined by Mars and Saturn equally spaced to either side. To be sure, this 
year's Gems were moonstones.

   Last night, Larry Wood and I headed out to a dark location near Devon, 
Alberta. We found an excellent spot on the aptly-named Sanctuary Road, no 
local yardlights and zero traffic, not a single car in the nearly three 
hours we were there. Now when I say "dark location", that would be in 
theory; in practice the bright moonlight lit up a haze of cirrus of variable 
thickness, most of the night casting an impressive 22° halo which nicely 
framed Betelgeuse and Bellatrix below, Menkalinan and Capella above. Also, 
the light skiff of snow was brilliantly lit; let's just say we didn't have 
any trouble setting up.

    Nonetheless, the brighter stars shone through most of the time we were 
there, limiting magnitude ranged from 3 to 4 for the most part, and we could 
always see a fair chunk of sky. We used Larry's truck to block out direct 
moonlight and concentrated on the northern half of the sky. We both knew 
counts would be low, but neither of us bargained on the blank sky we 
encountered. In two and a half hours of almost-continuous observing (from 
23:08 to ~01:40 MST), I logged only five Geminids and three sporadics. 
Larry's results were similar.

    Luckily, close to 1 a.m. we both spotted the explosion point of a 
fireball through fairly thick clouds above the northern treetops which was 
at least mag -3, and a few minutes later we both got a good look at a very 
pretty -1 Gem with a nice 20° train near the Little Dipper. But that was 
about it; two of my five Gems were mirages that I counted only when I 
realized they came straight from the radiant, and there was nothing special 
about the sporadics either. All in all, I would call the post-peak Geminids 
a disappointing no-show.

    I'm never unhappy to get out under stars even under the most marginal of 
circumstances, so the night wasn't a complete write-off, if only to give a 
visual exclamation point to my much more scientifically useful radio 
results. More on this in the next post.

   Bruce