Detailed visual observations and modelling of the 1998 Leonid shower

ABSTRA C T We present a detailed activity profile for the 1998 Leonid shower from visual observations. The shower displayed at least two distinct components ‐ a broad component peaking between 2348 4 and 2358: 0, and two narrower filaments near 2358: 21 and 2358 33 probably of younger origin based on modelling results. This dual-peaked structure in the flux profile has peak fluxes to a limiting magnitude of 16.5 of 0.03 Leonid km 22 h 21 . The distribution of particles also changes dramatically across the stream in 1998, with large meteoroids dominating the early peak and smaller meteoroids relatively more abundant near the time of the nodal passage of the comet. Detailed comparison of the observed activity with models in 1998 shows that the early component comes from material ejected between 500 and 1000 yr ago. Our modelling results suggest that the later dual peaks are caused by high-b meteoroids with large ejection velocities released during the 1932 and 1965 passages of Comet 55P/ Tempel‐Tuttle.