The third peak of the 1998 Leonid meteor shower

The Leonid meteor shower in November 1998 was observed widely by astronomers. The first peak, rich in bright meteors, appeared about 16 hours before the predicted maximum of the main shower. The main shower was also observed by both optical and radio methods during 19:00-21:00 UT on Nov. 17, and the radio peak was over 2500 h(-1). About 18 hours after the main shower, an abnormal phenomenon in the ionosphere was detected by two separate ionosphere observing stations. And the very high abnormal phenomenon maintained over one flour. The phenomenon showed that the ionosphere was injected with a large amount of small dust particles that could not be observed in optical and radio. The observational results show that the Leonid meteor shower in 1998 had three peaks.