DRACONID OUTBURST OVER JAPAN!
We are certain now: eastern Asia was the best place to be for viewing the Draconid shower. Again. After reporting an unusual outburst of Draconid meteors in 1985, it was again the Japanese observers who reported witnessing the return of the shower in the evening of October 8, 1998. Rates went up to over 100 Draconids per hour. Observer J. Watanabe counted 28 meteors visually from 13h UT through 13h30m UT at the peak of the shower, even with a low radiant position and a nasty Moon. The time of the peak was much earlier than expected by many others, but Russian astronomer E.A. Reznikov of the South Ural University saw his modeling predictions nicely confirmed.
This successful prediction increases our hopes for correctly anticipating the time of the peak during the upcoming Leonid returns. Unlike the short-period Draconids, the Leonid meteoroids are much less perturbed by the planets.
A first impression of the Draconid return is shown above in a graph by Leonid MAC Instrument PI, Dr. Jiri Borovicka, derived from radar observations at Ondrejov Observatory in the Czech Republic. This graph shows that the Draconids were first detected around 11:00 UT and the outburst lasted until about 16:00 UT. Zhu Jin from the Beijing Observatory in China, local organiser of our upcoming Leonid ground-based campaign at Xinglong station, observed the shower at the future Leonid observing site. During 44 minutes of observations under bad moonlight conditions (faintest star visible was just about 4.2 magnitude), Zhu Jin saw 26 Draconids and 5 Sporadics.
Other first results from the Draonid shower are given here:
Visual: Japan, China
Visual outside outburst: Germany, Italy, U.K., California, Malta, Netherlands
Radio forward meteor scatter: The Netherlands, Austria, Portugal, Japan
Expected activity: Marshall Space Flight Center Space Science News
TANTALIZING HINTS OF CHARGED DUST GRAINS IN METEOR TRAILS
In a paper "Detection of a meteor contrail and meteoric dust in the Earth's upper mesosphere" (J. of Atmospheric and Solar-Terrestrial Physics, Vol. 60, No. 3, p. 359-369, 1998), Mike Kelley, C. Alcala and J.Y.N. Cho of Cornell University and the Arecibo Observatory report on a remarkable structure observed during a rocket flight 15 years ago. Kelley had noticed a brief increase of electron density when the rocket arrived at 92 km altitude, but thought little of the observation until he observed one of those long-lasting persistent trains for which Leonids are famous during the Leonid return of November 1996. His team subsequently uncovered radar observations around the same time showing a reflection falling gradually from 93 to 91.5 km altitude. Kelley et al. concluded that in an unlikely chance of fate, the rocket had crossed the long-lasting persistent train of a bright meteor on June 17, 1983. The observations showed sharp borders between the diffuse region and the meteor trail (as seen in visual observations -PJ) and Kelley et al. concluded that something was slowing down the diffusion rate of the electrons. That something might well be charged dust grains, perhaps the first detection of dust particles in a meteor persistent train.