Now for the second night of observing in Texas!
At sunset, we got set for another full night of observing. I especially excited about this night for a few reasons… For one thing, the exact time of the broad maximum had occurred just a few hours before nightfall, so we anticipated that the Geminids would still be plenty active again tonight. Then, as the activity starts declining quickly, a period of BRIGHT geminids occurs (known as the mass-sorting effect) accompanied by very bright fireballs! I was very excited about the possibility of seeing this! In many past years, I have tried and failed to see the mass-sorting effect due to the narrow window of opportunity (either missed because it occurs in the daytime, or behind cloud cover). At best, I’ve only seen it partially. This time, I felt I had a shot seeing it through the best part of the night!!
The sky was very clear with excellent transparency, steady mag 7 skies (after moonset), calm air, temperature again very comfortable for us especially for a clear mid-December night (+7C at the start, down to -2C late at night, and some humidity/ground fog late at night). We enjoyed listening to several coyotes on this night!
I wasted no time, starting my watch in the early evening just as the radiant rose in the east — to check for earthgrazers. In that hour, I saw 22 Geminids, some of which had gorgeous long path lengths. Most were rather dim, so I started questioning that perhaps I had already missed the “bright meteor period” as I had on so many other occasions in previous years? So I took a break to wait for the radiant to climb, the Moon to set, and resumed observing just before 10pm. In the hour that followed, I saw 43 Geminids plus sporadics and other minor showers, so it was looking good! The meteors got gradually brighter and brighter!
Starting at 11pm, the Geminids suddenly started getting a LOT brighter!! WOW!!! It felt like a VERY different shower with one BRIGHT COLORFUL Geminid after another, some seen high up and many others seen very low against the flat open horizons. The rates were also surprisingly high, and easily surpassed my expectations knowing that the peak was now well behind us. The rates approached and then surpassed one meteor per minute, and that pace held up until 2:30am. It sometimes felt like this was actually the more active night, especially with all the bright meteors. 11 fireballs were seen (-7, -5 two -4s and seven -3s) along with a plethora of -1s, 0s and +1s! Lots of vivid blues, greens and yellows too!
After that, the rates dropped precipitously. I was definitely getting tired after 4:00am, but it was evident that the shower was well on its way out. Only 10 Geminids were seen in the final 40 minutes, and they were fainter now. I was absolutely pleased… what a spectacular and thrilling night!!! In 6.5 hours of viewing, I saw a total of 302 meteors! On top of the Geminids, there was also decent activity from the Monocerotids, Hydrids, anthelions and sporadics. One of these was a colorful mag 0 streak that shot 60 degrees!
It is difficult to say which of the two main nights were better… both were spectacular for different reasons! Finally, I saw the famous Geminid “mass sorting” effect… it’s definitely a real thing!!! We were very lucky to see this; has the peak occurred just a few hours earlier in the day, this night would have been a lot quieter. Look at the pictures on the Smugmug below and then compare them with the ones from the previous night. You’ll see the difference!
Night of Dec 14/15 2015 photos (scroll down the webpage to see each images & captions):
Detailed data below:
December 14/15 2015, 01:25-10:55 UT (19:25-04:55 CST)
Location: Comanche Springs Astronomy Campus (near Crowel), Texas, USA
(Long: -99.957 West; Lat: 33.991 North)
Observed showers:
Anthelion (ANT) – 06:16 (094) +23
Monocerotids (MON) – 06:52 (103) +08
Geminids (GEM) – 07:33 (113) +32
Sigma Hydrids (HYD) – 08:24 (126) +02
Dec. Leonis Minorids (DLM) – 10:08 (152) +35
Psi Ursa Majorids (PSU) – 11:44 (176) +42
Dec. Alpha Draconids (DAD) – 13:52 (208) +58
01:25-02:35 UT (19:25-20:35 CST); clear; 5/5 trans; F 1.00; LM 6.70; facing E50 deg; teff 1.16 hr; temp: +6C, crescent moon in western sky
GEM: Twenty-two: -3; -1; 0; +1(4); +2(4); +3(4); +4(2); +5(5)
ANT: one: +4
Sporadics: two: +2; +4
Total meteors: Twenty-five
03:55-04:56 UT (21:55-22:56 CST); clear; 5/5 trans; F 1.00; LM 7.00; facing SE50 deg; teff 1.01 hr; temp: +4C
GEM: Forty-three: -2; -1(2); 0(5); +1(14); +2(8); +3(6); +4(3); +5(4)
MON: four: +4(3); +5
ANT: one: +4
HYD: one: +5
Sporadics: six: 0; +1; +4(3); +5
Total meteors: Fifty-five
04:56-05:57 UT (22:56-23:57 CST); clear; 5/5 trans; F 1.00; LM 7.00; facing SE50 deg; teff 1.01 hr; temp: +2C
GEM: Fifty-four: -4; -3(3); -2; -1(5); 0(4); +1(10); +2(5); +3(7); +4(11); +5(6); +6(1)
ANT: one: +5
Sporadics: five: +1; +2; +4(2); +5
Total meteors: Sixty
05:57-07:28 UT (23:57-01:28 CST); clear; 5/5 trans; F 1.00; LM 7.00; facing S50 deg; teff 1.00 hr; temp: +1C
GEM: Fifty-eight: -7; -4; -2; -1(3); 0(7); +1(8); +2(8); +3(10); +4(6); +5(13)
MON: two: +4
HYD: one: +4
DLM: one: +1
Sporadics: five: +4(3); +5(2)
Total meteors: Sixty-seven
07:28-08:28 UT (01:28-02:28 CST); clear; 5/5 trans; F 1.00; LM 7.00; facing S50 deg; teff 1.00 hr; temp: -1C
GEM: Forty-three: -5; -3(2); -2; -1; 0(4); +1(5); +2(7); +3(7); +4(10); +5(5)
MON: three: +1; +4(2)
HYD: two: +1; +4
ANT: one: +4
DLM: one: +4
Sporadics: seven: +1; +2; +3; +4(4)
Total meteors: Fifty-seven
08:28-09:00 UT (02:28-03:00 CST); clear; 4/5 trans; F 1.00; LM 6.70; facing S50 deg; teff 0.53 hr; temp: -2C
GEM: Sixteen: -3; -2(3); -1; 0(2); +1(2); +2; +4(4); +5; +6
ANT: one: +3
Sporadics: one: +6
Total meteors: Eighteen
09:52-10:55 UT (03:52-04:55 CST); clear; 4/5 trans; F 1.00; LM 6.60; facing S50 deg; teff 0.70 hr; temp: +1C
GEM: Ten: +1; +2(5); +3(4)
MON: one: +3
HYD: one: +3
Sporadics: eight: +3; +4(6); +5
Total meteors: Twenty
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SHORT PERIODS (number of meteors, in 10 minutes TEFF periods)
01:25-01:35 UT; FOV RA 051 dec +12; LM 6.70; teff 0.166; GEM: one
01:35-01:45 UT; FOV RA 051 dec +12; LM 6.70; teff 0.166; GEM: five
01:45-01:55 UT; FOV RA 051 dec +12; LM 6.70; teff 0.166; GEM: one
01:55-02:05 UT; FOV RA 051 dec +12; LM 6.70; teff 0.166; GEM: four
02:05-02:15 UT; FOV RA 051 dec +12; LM 6.75; teff 0.158; GEM: three
02:15-02:25 UT; FOV RA 051 dec +12; LM 6.80; teff 0.166; GEM: four; SPO: two
02:25-02:35 UT; FOV RA 051 dec +12; LM 6.90; teff 0.166; GEM: four; ANT: one
** BREAK 02:35-03:55 **
03:55-04:05 UT; FOV RA 069 dec -03; LM 7.00; teff 0.166; GEM: six; ANT: one; SPO: one
04:05-04:15 UT; FOV RA 069 dec -03; LM 7.00; teff 0.166; GEM: six
04:15-04:25 UT; FOV RA 069 dec -03; LM 7.00; teff 0.158; GEM: eight; SPO: one
04:25-04:35 UT; FOV RA 069 dec -03; LM 7.00; teff 0.166; GEM: ten; MON: one; SPO: two
04:35-04:45 UT; FOV RA 069 dec -03; LM 7.00; teff 0.166; GEM: five; MON: two; SPO: one
04:45-04:55 UT; FOV RA 069 dec -03; LM 7.00; teff 0.166; GEM: eight; MON: one; HYD: one; SPO: one
04:55-05:05 UT; FOV RA 081 dec -08; LM 7.00; teff 0.166; GEM: eight
05:05-05:15 UT; FOV RA 081 dec -08; LM 7.00; teff 0.158; GEM: twelve; SPO: one
05:15-05:25 UT; FOV RA 081 dec -08; LM 7.00; teff 0.166; GEM: eleven
05:25-05:35 UT; FOV RA 081 dec -08; LM 7.00; teff 0.166; GEM: three; ANT: one; SPO: two
05:35-05:45 UT; FOV RA 081 dec -08; LM 7.00; teff 0.166; GEM: twelve; SPO: one
05:45-05:55 UT; FOV RA 081 dec -08; LM 7.00; teff 0.166; GEM: seven; SPO: one
05:55-06:05 UT; FOV RA 079 dec -08; LM 7.00; teff 0.166; GEM: nine; DLM: one; MON: one
06:05-06:10 UT; FOV RA 079 dec -08; LM 7.00; teff 0.077; GEM: five
** BREAK 06:10-06:40 **
06:40-06:50 UT; FOV RA 079 dec -08; LM 7.00; teff 0.161; GEM: ten; HYD: one
06:50-07:00 UT; FOV RA 079 dec -08; LM 7.00; teff 0.166; GEM: ten
07:00-07:10 UT; FOV RA 079 dec -08; LM 7.00; teff 0.166; GEM: five; SPO: two
07:10-07:20 UT; FOV RA 079 dec -08; LM 7.00; teff 0.166; GEM: eleven; SPO: three
07:20-07:30 UT; FOV RA 079 dec -08; LM 7.00; teff 0.166; GEM: eleven; MON: one
07:30-07:40 UT; FOV RA 104 dec -05; LM 7.00; teff 0.166; GEM: six; HYD: two; SPO: one
07:40-07:50 UT; FOV RA 104 dec -05; LM 7.00; teff 0.166; GEM: fourteen; MON: one
07:50-08:00 UT; FOV RA 104 dec -05; LM 7.00; teff 0.166; GEM: five; ANT: one; MON: one; SPO: one
08:00-08:10 UT; FOV RA 104 dec -05; LM 7.00; teff 0.166; GEM: ten
08:10-08:20 UT; FOV RA 104 dec -05; LM 7.00; teff 0.166; GEM: four; SPO: two
08:20-08:30 UT; FOV RA 104 dec -05; LM 6.90; teff 0.166; GEM: two; DLM: one; MON: one; SPO: three
08:30-08:40 UT; FOV RA 106 dec -09; LM 6.80; teff 0.166; GEM: seven; SPO: one
08:40-08:50 UT; FOV RA 106 dec -09; LM 6.80; teff 0.166; GEM: five; ANT: one
08:50-09:00 UT; FOV RA 106 dec -09; LM 6.70; teff 0.166; GEM: four
** BREAK 09:00-09:52 **
09:52-10:02 UT; FOV RA 116 dec -09; LM 6.60; teff 0.166; GEM: three; SPO: one
10:02-10:14 UT; FOV RA 116 dec -09; LM 6.60; teff 0.200; GEM: two; MON: one; HYD: one; SPO: one
** BREAK 10:14-10:55 **
10:18-10:55 UT; FOV RA 116 dec -09; LM 6.60; teff 0.333; GEM: five; SPO: six
Clear skies,
Pierre Martin
Ottawa, Ontario
Great report and pictures Pierre!