The Leonid meteor shower this year (1999) started off with rates lower
than those observed over the last few years. However, late on the 17th
and in the early hours of the 18th (UT), rates rose to a spectacular peak
of around 5400 (corrected Zenithal Hourly Rate). The main graph below
shows, on a logarithmic scale the time history, over 5 days, of
this year's Leonid shower. It was drawn using preliminary
International Meteor Organisation data and supplemented
by data taken at Learmonth.
Meteor rates rose above 1000 ZHR (the traditional definition of a meteor
storm) for a period of 70 minutes from 0130 to 0240 (UT) on the 18th. The
central peak of the storm is shown in detail in the inset graph drawn
below using a linear scale. This also shows that the half width of the storm
was around 25 minutes. Note also a much smaller secondary
maximum at around 18/1600UT.
As in 1998, it was observers in Europe who were best placed to observe
the Leonids' peak outburst this year. It was noted that fainter
meteors formed a greater percentage of the total population
than they did in the last three years. The percentage of long
duration trains was also less than in previous years. One
observer reported counting 55 meteors per minute around
the peak time of 0205UT.
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