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Location: Chemistry/Physics Building, MUN
Time: 8:00 pm
Present: 29
1. Randy's Intro (Fred is out of town). Continuing Education at MUN will be holding an astronomy course on June 9. We are looking for volunteers to teach sections or to help out (there probably will be an observing session).
Observations. Garry Dymond: At the Canadian Dollar Shop you can get real cheap red lens flashlights for $2 each. Garry also saw the comet by Orion. Chris Stevenson: galaxies with binoculars, plus meteors. Robert Babb: before summer was over a couple of weeks ago he saw some of the fantastic aurora. Randy: a fellow by the name of Whiffen from the West Coast has a scope for sale. Ben Llewellyn: viewed Orion, Gemini, Jupiter and Saturn. Phil McCausland: Mars is in retrograde motion.
2. Phil's Talk on the Tagish Lake Event. First Phil talked about GA 2001, which will be held in London, his newly adopted Centre. He passed around some brochures and some monolith bookmarks for "2001: a space rasc" (the GA). These have serial numbers on them which will be used for prizes at the GA and also are used when you visit the web site (a doubly neat idea). The registration deadline for the GA has been extended.
Fall and Recovery of the Tagish Lake Meteorite. As usual, Phil has an impressive talk, one dense with information and overheads. I will only outline his talk in the broadest fashion. Much of the history of the Tagish event can be found in such references as Sky and Telescope. Phil became involved in the joint field party sent by the University of Western Ontario and the University of Calgary. This was largely organized by Peter Browne and Alan Hildebrandt. Much of the success in their recovery can be attributed to the fortuitous line the ground track of the meteor took in relation to nearby communities and to a local road. Due to its time at 8:45 am there were many observers. This was combined with US Department of Defense satellite information to produce a likely fall location with pretty good confidence. The meteorite was estimated to be about 200 tonnes and travelling at about 16-17 km/s from all this information. Only one or two of these strike the earth every year. The resulting orbit of low inclination reached out to about 3AU (mid-outer asteroid belt). This is now the 5th meteor with a known orbit (and the first of the carbonaceous variety).
Thanks to a keen and knowledgeable local, Jim Brooke, frozen samples were taken and kept that way one week after the event. He was a geologist by training. Phil described the make up of the meteorite, chemically, and related how it was most likely formed from the early solar nebula, according to current theory.
Finally, Phil described in some detail the logistics of how the search took place (mostly on the frozen lake) up to the point that the river became too dangerous due to the spring conditions. Searching for meteorite fragments embedded in a lake and then retrieving them is a pretty tedious job (you also have to know the difference between a possible fall and decayed leaves, dung, and other nasties). Depending on the size and type of fragment, several techniques were used, ranging from sucking it up, spooning it up, and using a chainsaw to carve out and preserve the entire specimen. Most of their specimens had reached a sludge-like state thanks to the intervening time from the fall, though they did recover a few pristine specimens much like the ones Jim Brooke had recovered. The material is so delicate that the addition of a bit of water caused a solid specimen to degrade to a paste like state in short order.
3. Coffee
4. Robert Babb on the Sky Next Month
Mars will be best in June around 12 to 1 am. Jupiter and Mercury will be close in the west. Now is an ideal time to go looking for Mercury. Comet Linear 2001 A2 is visible. His list of objects will be printed on the web.
June will be our last meeting for the summer. John Carter will be speaking. We start up again in September.
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Please send any additions or corrections to:
David Bourgeois: mailto:dbourgeo@nl.rogers.com