(meteorobs) 2008 Quadrantids from Alberta

[Bruce McCurdy]

    Although my "Great Meteor Project of 2007" was formally completed with 
observation of a handful of Ursids in the nights before Christmas, there was 
no way I was going to miss the Quadrantid shower, which follows the turn of 
the Gregorian calendar but clearly marks the end of the meteor year. My 
previous experiences with this elusive shower had been hampered by low 
radiant position and/or bright moonlight, if not completely scotched by 
hopeless weather. The skies didn't appear too promising on this occasion 
either, but the narrowness of the peak left few options but to make the 
attempt.

    It is my great good fortune to have a skilled meteorologist for an 
observing buddy -- I highly recommend it! -- and once again Alister 
delivered in spades. He pointed us south and west to meet a chinook arch 
coming off the Rockies, and after a two-hour drive we emerged under the arch 
just past Buck Lake, found a comfortable nook to park off a tertiary highway 
with minimal traffic. We started observing at 06:40 UT, right at the 
predicted peak of this year' Quads, with hopes of seeing one shoulder of the 
shower. While real rates were expected to drop sharply, this should be 
moderated somewhat by the rising radiant.

    The first two hours were fairly indifferent, as we looked through patchy 
cloud into murky skies, entirely typical (Alister assured me) of chinook 
winds. He also advised there should be a heavier band of cloud at the back 
edge that would take an hour or two to clear out but have clear skies behind 
it. When this band materialized, instead of quitting as I might have done 
without the expert advice, we both grabbed a power nap in the crisp 
foothills air for about 90 minutes. I awoke to see that back edge passing 
through overhead, and a gorgeous -2 Quad with a long wake and persistent 
train greeted me within a minute. We settled in for a further four-hour 
session right into morning twilight, figuring that if we had been too far 
west to see the peak, we might nonetheless collect valuable data about the 
shoulder that wouldn't be available to observers to the east. The sky was 
much improved, and the radiant which had dawdled low in the northeast in our 
first hours was beginning to soar, and meteor counts with it.

    The Quadrantids delivered a very satisfying show. In 6 hours Teff I 
observed 92 Quads, which I guess is "only" 15 per hour but seemed like more. 
There was lots of sporadic activity and we were both able to identify a few 
members of three minor radiants. My night's total of 158 meteors exceeded my 
highest count in a very busy 2007, as did my best hour of 43 total meteors. 
That hour, 11:30 to 12:30 UT, featured 29 Quads some four hours after the 
newly-derived peak of ~08 h. It also featured a radiant over 50° high and 
the most transparent skies of the night, two other important variables. 
(Indeed, I am less than 100% satisfied with my limiting magnitude estimates, 
obtained by the star count method but probably not at frequent enough 
intervals.)

    Hourly counts are summarized at bottom in the usual fashion, but given 
the variation in activity I have refined the raw numbers into 15 minute bins 
of Quads and all others. If more detail is required please write to me 
off-list.

Interval (UT)    QUA    Others
--------------------------------
06:40 - 06:55        0        3
06:56 - 07:10        0        1
07:11 - 07:25        2        1
07:26 - 07:40        3        1
07:41 - 07:55        1        2
07:56 - 08:10        2        0
08:11 - 08:25        7        3
08:26 - 08:40        4        1
...
...
10:30 - 10:45        5        1
10:46 - 11:00        1        2
11:01 - 11:15        3        4
11:16 - 11:30        7        7
11:31 - 11:45        7        3
11:46 - 12:00        7        7
12:01 - 12:15        7        2
12:16 - 12:30        8        2
..
12:35 - 12:50        2        5
12:51 - 13:05        7        3
13:06 - 13:20        0        4
13:21 - 13:35        3        5
13:36 - 13:50        7        5
13:51 - 14:05        6        2
14:06 - 14:20        2        1
14:21 - 14:35        1        1
----------------------------
Totals                  92      66

    When considering the hourly counts the Quads appeared to rebound from 12 
to 16 in the last hour, however no fewer than 5 of these occurred in the 
first 4 minutes of that final hour, after which the pickings were pretty 
slim. Even accounting for the rising twilight it was apparent the Quads were 
on the way out, with just a single example seen in the last 25 minutes.

    In addition to our visual observations, Alister and I employed the car 
radio forward scatter method to listen to this very active sky, and by 
extension to our own dynamic planet. The airwaves were full of competing 
musical genres, and we heard announcers' voices place themselves in Montana, 
South Dakota, and two different locales in North Dakota (Bismarck and Rapid 
City). As usual the radio was a much more efficient observer than either of 
us, and the "hits" just kept on coming. :) A significant fraction of the 
meteors observed visually were accompanied by a confirmatory radio burst.

    As the night wore on Venus and the very low crescent Moon entered the 
scene in wide conjunction. The former proved a useful comparison object in 
the final hour when I spotted the two brightest meteors of the night just 
four minutes apart, a -4 sporadic with a 2-second persistent train and a -3 
white Quad with a 1.5-second train of its own. I saw one other -3 Quad of 
pale orange an hour or so earlier, and 9 others of low negative magnitude, 
but none in the fireball category. Nonetheless it was by far the best 
display of Quadrantids I have yet seen, well worth the long drive and the 
loss of sleep.

    Bruce
    *****


Observer: Bruce McCurdy, MCCBR
Location: Range Road 63, 2 km S of Highway 13 (near Buck Lake, AB), 52° 54' 
44" N., 114° 47' 53" W.
Date: 2008 January 4, 06:40 to 14:35 UT, Teff = 6.0 hours
Limiting magnitude: variable, 4.0 to 6.0, occasional translucent cloud cover
Primary method: visual, microcassette recorder and talking watch
Secondary method: audio, monitoring forward scatter by car radio (FM 94.5)

Active radiants:
Antihelion (ANT) - 07:52 (118) +20
Alpha Hydrids (Non-IMO Shower -- AHY?) - 08:32 (128) -13
Epsilon Leonids (Non-IMO Shower -- ELE) - 09:44 (146) +25
Coma Berenicids (COM) - 12:40 (190) +18
Quadrantids (QUA) - 15:20 (230) +49

Hour 1: 06:40-07:40 UT; murky with some cloud; LM = 4.0 to 5.0; facing E 60°
5 QUA: +1(2),+2, +3, +4
6 SPO: 0, +2,+3(3), +4
Total meteors: eleven
***

Hour 2: 07:40-08:40 UT; hazy; LM = ~5.0
14 QUA: -1, 0, +1, +2(3), +3(4), +4(4)
1 ANT: +2
1 AHY: +3
1 ELE: +4
1 COM: 0
2 SPO: +3, +4
Total meteors: twenty
***

8:40-10:30 break, cloudy

Hour 3: 10:30-11:30 UT; clearing; LM = 5.5 to 6.0
16 QUA: -2, -1(2), 0(3), +1, +2(2), +3(4), +4(3)
2 ANT: +2, +3
1 ELE: +2
1 AHY: +2
2 COM: +2, +3
8 SPO: +1, +3(4), +4(3)
Total meteors: thirty
***

Hour 4: 11:30-12:30 UT; clear, LM = 6.0
29 QUA: -2, -1(4), 0(2), +1(4), +2(4), +3(6), +4(8)
1 ANT: +3
1 COM: +1
12 SPO: -1, +2, +3(2), +4(5), +5(3)
Total meteors: forty-three
***

12:30-12:35: break

Hour 5: 12:35-13:35 UT, clear, LM = 6.0
12 QUA: -3, 0, +1, +2(3), +3(3), +4(4)
3 COM: +1, +2, +4
1 AHY: +3
13 SPO: 0, +2(3), +3(4), +4(5)
Total meteors: twenty-nine
***

Hour 6: 13:35-14:35 UT,some cirrus and rising twilight, LM = 5.9 to 5.2
16 QUA: -3, 0, +1, +2(6), +3(6), +4
5 COM: +1, +3(3), +4
4 SPO: -4, 0, +3(2)
Total meteors: twenty-five
***

Observing summary: 06:40-12:35, Teff = 6.0 hours, avg. LM = ~5.5
92 QUA: -3(2), -2(2), -1(7), 0(8), +1(10), +2(19), +3(24), +4(20)  [avg. = 
+2.0]
4 ANT: +2 (2), +3(2)  [avg. = +2.5]
3 AHY: +2, +3(2)  [avg. = +2.7]
2 ELE: +2, +4  [avg. = 3.0]
12 COM: 0, +1(3), +2(2), +3(4), +4(2)  [avg. = +2.3]
45 SPO: -4, -1, 0(3), +1, +2(5), +3(16), +4(15), +5(3)  [avg. = +2.9]
Total meteors: one hundred fifty-eight
*****