(meteorobs) Post-peak Geminids from central Alberta
Bruce McCurdy
bmccurdy at shaw.ca
Wed Dec 16 21:21:22 EST 2015
After several days and nights of wintry white skies over Edmonton and area, things finally cleared off for a few hours on Dec. 14-15. Alister Ling and I took advantage of the opportunity to head out to our primary dark site at Beaver Hills Dark Sky Preserve (Blackfoot) right after the RASC Edmonton Centre meeting Monday evening. Sky conditions were good not great, with the fresh snow brightening the entire scene including the ice crystals/cirrus. My sky quality meter wasn’t functional, but regular star counts within Limiting Magnitude Areas 4, 8, and 9 in Taurus, Gemini, and Leo all converged on a LM of a so-so 5.5. The temp was a crisp -10 C. or so, while a mild auroral arc sat above the northern horizon. I tracked that for a few minutes before turning my attention, and my camera, towards darker skies south, then east.
The peak had been about 14 hours earlier, so we expected lower rates but perhaps brighter meteors, the so-called “photographic maximum” that Paul Jones referred to on the MeteorObs list the other day. We set up our cameras for about 3½ hours, and spent most of that time visually observing as well. I got 140 minutes of Teff, 80 facing south, a 20-minute break, then a further hour facing east. In both cases I kept my camera’s field of view within my own, and my audio notes proved a very useful technique to search and cross-reference possible captures, of which I got at least 8 decent meteors including 2 in one frame that exactly matched an observation of mag 0 and -1 GEMs about five seconds apart.
In all I counted 74 meteors (56 GEMs) in the full session, so about one meteor every two minutes though as usual they seemed to occur in clumps. All were contained on ~50 audio notes, many of which contained 2, 3, or even 4 meteors in one verbal. The Anthelions were mildly active, while I also caught a few Sigma Hydrids, and one rapid member of each of the December Leonis Minorids and Psi Ursa Majorids.
The sessions naturally divided into 20-minute bins, of which the last was the most fruitful with 13 GEMs and 19 total meteors even as none were bright. My IMO report form is reproduced at bottom. It contains one tiny error, one -2 GEM got reported as a +2. (Speaking of IMO, I’m a little surprised that IMO.net doesn’t have its usual activity profile for the Geminids, especially given the favourable moon phase. Wondering what may have happened there.)
By far the best streaker of the session was a brilliant long Geminid fireball that lasted the better part of two seconds as it burned through the western sky, far from my camera field but well seen by eye. It was coppery coloured with an explosion point that I perhaps conservatively estimated at magnitude -6. No other meteors of brighter than mag -2 were observed during the count period, though Alister and I both saw another fireball, green in colour, dropping into the southwest during the drive home, that had to be at least mag -5. I saw another bright one on the ride that I estimated at -3 and was likely brighter since I observed it through the tinted part of my windshield. Made me wish we had stayed behind for another hour, though we did make it to our stated end time of 03:00 local time and were nearing our own limits of fatigue. We wouldn’t have had much longer anyway, in that by the time we made it back to the city the sky was clouding over fast.
Bruce
*****
-----Original Message-----
From: Bruce McCurdy [mailto:bmccurdy at shaw.ca]
Sent: Wednesday, December 16, 2015 5:11 PM
To: IMO report forms
Cc: bmccurdy at shaw.ca
Subject: Electronic visual form for 2015-12-15
// Header section
night 2015-12-14/15
begin 2015-12-15 0710
end 2015-12-15 0950
observer "Bruce" "McCurdy" "MCCBR"
location 112 46 48 W, 53 32 12 N
site "Beaver Hills Dark Sky Preserve (Blackfoot)" "Canada" "51128"
reporter " <mailto:bmccurdy at shaw.ca> bmccurdy at shaw.ca"
// Shower section
shower ANT 094 +23
shower DLM 152 +35
shower GEM 112 +33
shower HYD 127 +02
shower PSU 176 +42
shower SPO
// Number section
// Interval RA Dec Teff F Lm ANT DLM GEM HYD PSU SPO
period 0710-0730 080 +15 0.330 1.00 5.50 C 1 C 0 C 8 C 0 C 0 C 0
period 0730-0750 085 +15 0.330 1.00 5.50 C 2 C 0 C 5 C 0 C 0 C 0
period 0750-0810 090 +15 0.330 1.00 5.50 C 0 C 0 C 8 C 0 C 0 C 1
period 0810-0830 095 +15 0.330 1.00 5.50 C 1 C 0 C 6 C 0 C 0 C 0
period 0850-0910 150 +30 0.330 1.00 5.50 C 0 C 0 C 9 C 2 C 0 C 1
period 0910-0930 155 +30 0.330 1.00 5.50 C 0 C 1 C 7 C 1 C 0 C 2
period 0930-0950 160 +30 0.330 1.00 5.50 C 1 C 0 C 13 C 0 C 1 C 4
// Magnitude section
// Show Interval -6 -5 -4 -3 -2 -1 +0 +1 +2 +3 +4 +5 +6 +7 Tot
distribution GEM 0710-0730 - - - - 1.0 1.0 - 1.0 1.0 4.0 - - - - 8.0
distribution GEM 0730-0750 - - - - - - - 2.0 - 2.0 1.0 - - - 5.0
distribution GEM 0750-0810 - - - - - 1.0 2.0 - 2.0 2.0 1.0 - - - 8.0
distribution GEM 0810-0830 1.0 - - - - - - 1.0 2.0 1.0 1.0 - - - 6.0
distribution GEM 0850-0910 - - - - - - 1.0 1.0 1.0 4.0 1.0 1.0 - - 9.0
distribution GEM 0910-0930 - - - - - - 2.0 2.0 2.0 1.0 - - - - 7.0
distribution GEM 0930-0950 - - - - - - - 2.0 2.0 4.0 5.0 - - - 13.0
distribution ANT 0710-0830 - - - - - 1.0 1.0 - - 1.0 1.0 - - - 4.0
distribution ANT 0850-0950 - - - - - - - - 1.0 - - - - - 1.0
distribution DLM 0850-0950 - - - - - - - - - 1.0 - - - - 1.0
distribution HYD 0850-0950 - - - - - - - - 1.0 1.0 1.0 - - - 3.0
distribution PSU 0850-0950 - - - - - - - 1.0 - - - - - - 1.0
distribution SPO 0710-0830 - - - - - - 1.0 - - - - - - - 1.0
distribution SPO 0850-0950 - - - - 1.0 1.0 1.0 1.0 1.0 1.0 - 1.0 - - 7.0
// Personal comments
Post-peak observations of 2015 Geminids from central Alberta
2.33 hours of Teff:
1.33 hours facing south, then the last 1.00 hours (after a 20-minute break) facing east
----
Members of Anthelion radiant (ANT), December Leonis Minorids (DLM) and Psi Ursa Majorids (PSU)
as per AMS (Lunsford) were identified.
No Monocerotids were identified.
---
One orange fireball of estimated -6 was observed in-session,
while another of -5 was observed during the drive home,
as was another bright meteor of estimated mag -3.
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