(meteorobs) An evening with the Quadrantids

Now that is what I call a very civilized meteor shower. Imagine, a productive session of meteor observing from 7 to 11 p.m. On a moonless Friday evening, no less. I wouldn't have thought it possible.

Although initial forecasts suggested North America was unfavourably situated for the Quadrantids peak, there are advantages to living way up here in the Far North (54° N. latitude), and one of them is that the Quads radiant is nicely circumpolar. As Bob Lunsford wrote to me,

After virtually skunking us for the Leonids and Geminids, the weather cooperated almost perfectly. Kim Youmans might not agree, but at only a few degrees below freezing it was a balmy January evening requiring only four or five layers. (This ain't Georgia. The last time people in these parts observed the Quads, it was minus 26.) It cleared off about 6:30 p.m. local time (MST), and clouded up again shortly after 11, but in the interim I got four solid hours in, doing the Quads on the fourth day of the new year (UT).

Anyways, my count was of course greatly diminished by the altitude of the radiant, which transited the northern (!) meridian right in the middle of the session, around 9 p.m. local time. It therefore remained at a near constant 13-15° altitude throughout the session as it rotated across the bottom of its arc from northwest to northeast, reducing observed rates to a quarter of the derived ZHR.

There were four of us at the Blackfoot observing site, the primary dark-sky site of the Edmonton Centre RASC. In alphabetical order, we were Alister, Bruce, Chris, and Dave, which by my reckoning gave us half an octave of observers. Alister and I were there specifically to count meteors, and since he arrived first he got the fabulous Winter Hexagon replete with guest planets while I turned to the northern horizon. A huge single curl of mild aurora split the sky from north to south horizons, receded for a while, then came up again in the neighbourhood of the radiant, eventually forcing me to turn to the east and south. Midway through the evening a ripple of cirrus cloud passed through, slightly reducing our limiting magnitude.

While counts were fairly modest, I was impressed by the quality of the individual meteors, with a good half of them warranting individual descriptions on my microcassette recorder. None were excessively bright, but their intermediate speeds prompted descriptors like "majestic" or "stately", and several of the nicer ones lasted a second or more as they arced across a significant segment of the sky. A number of them were distinctly orange in colour, including one beauty that passed midway between Betelgeuse and Aldebaran and resembled both, in brightness and colour. Due to the situation of the radiant, many passed above the tree tops in a virtually horizontal fashion and most of the rest were rising up in the sky. I got the impression I was seeing the top half of the shower, but of course it would have been much less than that.

As usual I counted in ten minute bins, observing continuously without distraction for all but two or three minutes. All non-Quads were counted as "sporadic" although I know this isn't strictly correct. The two best bins (five Quads each) occurred consecutively between 0250 and 0310, however because they occurred in separate hours the bunching is not apparent in the following:

One surprise was that half the sporadics occurred in the first hour. Is there any reason sporadics might be more common in the early evening hours? I can't think of one, other than possibly a more alert observer. As mentioned, half the meteors in the second hour came in the first ten minutes, and pickings were very slim for the next two hours before a nice rebound in the last hour.

Alister also conducted car radio counts, although I don't know his results I do know they were in the single digits in most bins, at maybe two or three times the visual rate.

At my home radio system, the recently-christened Northern Claw Radiometeor Observatory, I had hourly counts of 8, 6, 10, and 19 in the same period as my visual watch, but the antenna is pointed southeast which I think is not so efficient for a radiant in the north. Radio counts continued to rise to 25, 15, and 21 in the subsequent three hours (0600-0900 UT) long after the predicted peak, suggesting that the angle of antenna offset to the radiant is an important consideration for which allowances need be made. In general it was a much quieter radio shower than the Geminids, at least near as I can tell with my current configuration.