(meteorobs) Geminids peak night in Iowa

pmartsching at mchsi.com pmartsching at mchsi.com
Sat Dec 15 11:31:04 EST 2012


Some forecasts said "partly cloudy" and some said "mostly clear" for central Iowa.  There had been a lot of jet contrail cirrus all day, along with some "natural" high cloud which got much worse toward sunset.  Weather satellite imagery seemed to show that worse was coming in.  I finally went out at 7 pm and the LM was fluctuating ~ 2.0 - 3.0. About 8:30 pm the average LM seemed to be around 3.5, so I decided I'd best get observing to see anything at all, and just in case sky conditions got worse again.  Conditions gradually improved, but I was bothered by more or less cirrus all night, tho there was very little during my last hour.  I dealt with the cirrus problem my making occasional average LM estimates for my FOV and I averaged these per hour in my report summary.  The sky conditions were so variable, that reporting my observations in time increments of less than one hour, would likely show more variation from cirrus problems, than from any actual variation in meteor rates.  

Meteor numbers were held down by the cirrus, but it was a good night anyway.  If I had observed from a darker location and was 20 years younger I would have seen a lot more.  Because of breaks, the beginning time of each hour sometimes shifted a few minutes - so in my report summary it appears that my best Geminid hour was only 55.  Taking 15 minute bins and picking out the best 4 consecutive 15 minute bins results in the best hour being from midnight to 1 am CST (06:00 - 07:00 UT) when I saw 65 Geminids.  This is what I thought while I was observing.  

The best Geminid was mag -10 at 05:34 UT.  It began red with the very large "pointy head" turning blue-white and forming a broad train which lasted 5 seconds - the longest duration train of the session.  This meteor ended about 5 degrees before a line connecting Polaris and the end of Cassiopeia, so was high in the sky and well placed to get a good look.  The next best Geminid (10:19 UT) was mag -7 yellow, which broke into two bright yellow pieces just before it ended, near Polaris.  Its train lasted 3 seconds.  The nicest sporadic (03:28 UT) was mag -3 red, medium speed, which began in the Hyades and ended 10 degrees below Polaris.

13/14 December 2012 (Thursday evening/Friday morning)
McFarland Park 4 miles NE of Ames, Story Co, Iowa, USA
Long: 93 deg 34 min W  Lat: 42 deg 05 min N  Elevation: 318 meters (1,043 feet)
Method: Visual; paper, pencils and talking clock

02:35-03:35 UT 31 deg F; dew pt 23 deg F; wind SW 9 mph; cirrus; average LM ~4.5; facing East 55 deg; teff 1.0 hour.
GEM: fifteen: -2; -1(2); 0(3); +1(5); +2(4)
Sporadics: three: -3; 0; +2
Total meteors: eighteen

03:35-04:35 UT 32 deg F; dew pt 23 deg F; wind: calm; cirrus; av LM ~5.0; facing E 55 deg; teff 1.0 hr.
GEM: thirty-one: -4(2); -3; -2(2); -1(3); 0(3); +1(10); +2(5); +3(5)
Sporadics: three: +1; +3(2)
Total meteors: thirty-four

04:35-05:35 UT 28 deg F; dew pt 22 deg F; wind: calm; cirrus; av LM ~5.3; facing E 55 deg; teff 1.0 hr.
DLM: one: +2
GEM: thirty-three: -10; -5; -4; -3(3); -2(2); -1(2); 0(7); +1(6); +2(4) +3(4); +4(2)
Sporadics: four: +1; +2; +3; +4
Total meteors: thirty-eight

Break 05:35-05:45 (10 minutes)

05:45-06:45 UT 25 deg F; dew pt 20 deg F; wind: calm; some cirrus; av LM ~5.5; facing E 55 deg; teff 1.0 hr.
DLM: one: 0
HYD: one: +3
GEM: fifty-five: -6; -5; -4; -3(4); -2(3); -1(2); 0(11); +1(8); +2(13); +3(7); +4(4)
Sporadics: five: -2; +1; +3(3)
Total meteors: sixty-two

06:45-07:45 UT 24 deg F; dew pt 22 deg F; wind: calm; cirrus; av LM ~5.4; facing E 55 deg; 1.0 hr.
DLM: one: +3
GEM: forty-six: -5; -3(3); -2(3); -1(3); 0(8); +1(6); +2(9); +3(9); +4(4)
Sporadics: one: +1
Total meteors: forty-eight

Break: 07:45 - 08:15 UT (30 minutes) 

08:15-09:15 UT 23 deg F; dew pt 19 deg F; wind: calm; cirrus; av LM ~5.5; facing E 55 deg; 1.0 hr.
ANT: one: -2
GEM: fifty-three: -5; -4(2); -3(3); -2(3); -1(4); 0(9); +1(12); +2(12); +3(7)
HYD: two: -4; +1
Sporadics: four: +1; +2; +3(2)
Total meteors: sixty

09:15-10:15 UT 22 deg F; dew pt 18 deg F; wind: calm; cirrus; av LM ~5.3; facing E 55 deg; 1.0 hr.
ANT: one: 0
GEM: thirty-eight: -5(2); -4; -3; -2(2); -1(2); 0(3); +1(9); +2(10); +3(7); +4
HYD: two: +3(2)
Sporadics: two: +3(2)
Total meteors: forty-three

10:15-11:15 UT 22 deg F; dew pt 19 deg F; wind: calm; very little cirrus; av LM ~5.6; facing E 55 deg; 1.0 hr.
DLM: one: +3
GEM: twenty-eight: -7; -4; -3; -2(4); -1; 0(6); +1(4); +2(3); +3(7)
HYD: one: +3
Sporadics: four: -2; +3(3)
Total meteors: thirty-four

Quit: very tired; fingers cold; twilight evident in East.  









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