First Results of the 1999 Perseid Meteor Shower

A preliminary analysis of the 1999 Perseids based on 17552 shower meteors seen by 174 observers in 1297 hours is presented. A clear activity peak at lambda=139.80+-0.01 (August 12, 1999, 23h05m UT) with ZHR=104+-4 is associated with the early maximum of the Perseids connected with the return of Comet 109P/Swift-Tuttle. The minimum of the population index occurs 45 minutes after this peak with r=1.82+-0.05. The actual peak coincides with a local r-maximum of 2.10+-0.07. The traditional maximum is barely visible in this first ZHR graph; a slight but not significant increase after the early peak was noted at lambda=139.9+-0.02 (August 13, 1999, 1h35m UT) with ZHR=87+-6. Similar to the returns in 1997 and 1998, we found an enhancement of activity after the traditional maximum, this year at lambda=140.45 +0.06 -0.20 reaching ZHR=80+-4.