(meteorobs) Observation December 12/13 2012 (Geminids adventure part I)

[Pierre Martin]

>>> Geminids adventure part I


Hello all,

Some of you will recall that Raymond Dubois and I drove to the Deerlick Astronomy Village (Georgia) back in 2010 to watch and photograph the Geminids.  It was such a wonderful and comfortable winter observing experience that we decided to do it again for this past December!  The Geminids promised an excellent show, thanks to excellent observing prospects (new moon).  So we easily talked ourselves into making a serious effort to catch that shower by going further south to clearer (and milder) skies.  About a week before the Geminids peak, it started to look as though a large high pressure was on its way over the U.S.  It was looking very good, so we made a final decision to go!  

The trip down was totally pleasant, and Raymond is a wonderful travel companion.  His meticulous planing and his experience with camping and long-distance road trips shows very well.  He's flexible to changes (i.e. weather) and was happy to assist when I ran into an issue (i.e. helping me find a proper AC/DC power adapter to run my mount and accessories).

From Ottawa, we drove 900km (9 hours) to get to Washington DC for a brief visit at Arlington Cemetery.  At that point, the weather forecasts looked a bit less favourable for Georgia.  It looked like there would be only one clear night.  We studied the weather forecasts and found that the high pressure was now favouring southern Ohio for two clear nights.  It was not too late to change directions.  Fortunately, one of the backup observing sites that I looked up before leaving home and brought along with me happened to be the Cincinnati Astronomical Society's Dark Sky Site (near Peebles, OH).  The site looked interesting in that it was dark (green class skies), had AC hookups, a large concrete platform, an area to setup tents, an outhouse and a warm room/bunk house (complete with microwave, tables, cot, red lights built-in, and various other things).  The microwave came in especially handy to warm up some Krispy Kremes at night ;)  More importantly, it looked like a safe spot to go to and leave our equipment out.  From our motel room, I emailed the key members of the CAS and they were kind enough to respond quickly with a variety of useful information.  Access to the site required a CAS membership, which I gladly paid via paypal.  So we drove 700km (7 hours) across the Appalachians and reached the CAS site by Dec 12th mid-afternoon.  We drove past the entrance, to be sure that we knew where it was, and then went to a nearby Walmart to get our food and supplies.  Back to the site, we found the entrance way to be a well maintained and solid concrete surface, and that's a good thing.  The site is located high up on a hill, and there's a steep incline to get up there!  A bit scary, but no problems.  At the top, we were greeted with a beautiful private observing site with an open view of the sky and a low tree line... perfect!!  The site was a bit soft and muddy with the mid-afternoon sun thawing the grounds, so we had to look around to find a dry enough spot for our tents.  We wasted no time setting up all our camera equipment on the pad to begin our session that night.  The sky was crystal clear without a cloud in sight!  Here's a few daytime pics of the setups:
http://goo.gl/SV28q
http://goo.gl/6YIsN
http://goo.gl/UDNQJ
http://goo.gl/QaIBl

I took my time that evening getting my two cameras up and running, and doing a variety of test shots.  I started observing formally at 10:30pm EST.  The sky was very good (4/5 trans, mag 6.5) and quite comfortable.  It sure felt nice being out observing again.  At 38 degrees latitude, Polaris was notably lower than I am used to seeing back home.  The Geminids (GEM) were already very active on this night, even though the predicted time of maximum activity was not until early the next evening.  I counted a total of 464 meteors (including 381 GEM) in over six hours of effective observing time.  This is my highest-ever count for a GEM pre-max night.  The busiest one-hour period came after 3:30am EST with 92 meteors (including 77 GEM).  The Geminids were fairly faint on average, which is typical for the pre-max night, including many meteors in the +3 to +4 mag range.  But a surprising crop of Geminid fireballs did appear that night (two -5s, one -4, two -3s).  The best was the mag -5 blue-white GEM at 3:45am that went 30 degrees and fragmented into two distinct pieces!  I also saw ten instances of a pair of Geminids appearing simultaneously (or nearly so).  Enhancing the observing experience was the chorus of distant coyotes, dogs and owls.  At the end of the night, the temperature was -4C and a heavy frost was covering everything.  By 6:30am, I packed a few things and retired to my tent just as morning dawn was underway.

Photo results for Dec 12/13:

http://goo.gl/6llK9
Composite of 5 Geminids captured early in the evening, stacked digitally, Canon 5D with Canon 15mm f/2.8 Fisheye, 
ISO800, 1 min exposures at f/2.8, tracked with Vixen GPDX

http://goo.gl/HYMrO
Composite of 26 Geminids captured between midnight and dawn, stacked digitally, Canon 5D with Canon 15mm f/2.8 Fisheye, ISO1000, 1 min exposures at f/2.8, tracked with Vixen GPDX

http://goo.gl/YsPjL
Composite of 33 Geminids captured between midnight and dawn, stacked digitally, Canon 7D with Canon 17-55mm f/2.8, ISO1250, 1 min exposures at f/2.8 (meteors); ISO800, 5 min exposure at f/4.5 (star field), tracked with Vixen GPDX

My formal report:

Dec 12/13 2012 03:30-11:20 UT (22:30-06:20 EST)
Breaks: 5:30-6:25, 9:13-25, 9:34-35, 9:50-10:07, 10:58-11:03 UT
Location: Cincinnati Dark Sky Site, Peebles, Ohio, U.S.A
(Long: 83 deg 27' 35" W; Lat: 38 deg 52' 32")

Observed showers and radiant position:
Geminids (GEM) - 07:28 (112) +32
Antihelion (ANT) - 06:12 (093) +23
Monocerotids (MON) - 06:48 (102) +08
Sigma Hydrids (HYD) - 08:16 (129) +02
December Leonis Minorids (DLM) - 10:22 (155) +34
Coma Berenicids (COM) - 11:30 (172) +19
December Alpha Draconids (DAD) - 14:00 (210) +58

Period 1:
03:30-04:30 UT; clear; F 1.00; LM 6.39; facing SE 50 deg; teff 1.00 hr.
GEM: forty-eight: -5; -1; 0(3); +1(4); +2(6); +3(13); +4(12); +5(8); mean: +2.85
ANT: two: +1; +5; mean: +3
Sporadics: five: +2; +3; +4(3); mean: +3.4
Total meteors: fifty-five

Period 2:
04:30-05:30 UT; clear; F 1.00; LM 6.48; facing SE 50 deg; teff 1.00 hr.
GEM: fifty-nine: -3; -1(2); 0(3); +1(2); +2(11); +3(15); +4(15); +5(9); mean: +2.86
MON: four: 0; +2; +3(2); mean: +2
HYD: two: +1; +3; mean: +2
ANT: one: +2
Sporadics: six: +1; +2; +3; +4(3); mean: +3
Total meteors: seventy-two

Period 3:
06:25-07:25 UT; clear; F 1.00; LM 6.48; facing SE 50 deg; teff 1.00 hr.
GEM: fifty-seven: -3; -1; 0(3); +1(6); +2(10); +3(14); +4(17); +5(5); mean: +2.75
MON: six: -2; +1; +2; +3(2); +4; mean: +2.33
ANT: five: +1; +3; +4(2); +5; mean: +3.4
HYD: one: +2
COM: one: +2
Sporadics: five: +1; +2; +3; +4(2); mean: +2.8
Total meteors: seventy-five

Period 4:
07:25-08:25 UT; clear; F 1.00; LM 6.48; facing SE 50 deg; teff 1.00 hr.
GEM: sixty-two: -1(3); 0(1); +1(7); +2(15); +3(17); +4(12); +5(7); mean: +2.71
ANT: two: +3; +4; mean: +3.50
MON: one: +1
HYD: one: +5
DLM: one: +1
Sporadics: seven: 0; +2; +4(4); +5; mean: +3.28
Total meteors: seventy-four

Period 5:
08:25-09:38 UT; clear; F 1.00; LM 6.48; facing SE 50 deg; teff 1.00 hr.
GEM: seventy-seven: -5; -1(2); 0(6); +1(5); +2(13); +3(18); +4(20); +5(12); mean: +2.80
ANT: three: +2(2); +3; mean: +2.33
DLM: three: +1; +3; +4; mean: +2.66
MON: one: +4
HYD: one: +3
COM: one: +3
Sporadics: six: +2(2); +3; +4(2); +5; mean: +3.33
Total meteors: ninety-two

Period 6:
09:38-10:55 UT; clear; F 1.00; LM 6.48; facing SW 50 deg; teff 1.00 hr.
GEM: sixty-three: -4; -1(2); 0(5); +1(9); +2(8); +3(11); +4(14); +5(13); mean: +2.74
ANT: two: +1; +5; mean: +3
HYD: two: +2; +5; mean: +3.5
DAD: two: +1; +4; mean: +2.5
Sporadics: six: +3(2); +4(2); +5(2); mean: +4
Total meteors: seventy-five

10:55-11:20 UT; clear; F 1.00; LM 6.48; facing SW 50 deg; teff 0.333 hr.
GEM: fifteen: -2; 0; +2(3); +3(6); +4(4); mean: +2.53
ANT: one: +2
DLM: one: +1
Sporadics: four: 0; +2; +5(2); mean: +3
Total meteors: twenty-one