Temporal Variation in the Orbital Element Distribution of the 1998 Leonid Outburst

Abstract

Double-station video observations of the 1998 Leonid shower from China resulted in 55 trajectories and orbits of meteoroids in the visual magnitude range from +0 to +6 magn. The 1998 Leonid outburst consisted of a relatively long duration shower that was rich in large meteoroids and peaked in the night of November 16/17, and an outburst of shorter duration that was rich in smaller meteoroids and peaked in the next night. The average orbit obtained during the first night agrees well with that from photographic observations. During the second night, the combined set of video and photographic observations shows temporal variation in the radiant distribution. This adds to the earlier discovery of an unusual asymmetric flux profile. In addition, the radiant distribution is shown to be mass dependent. The data suggest the presence of at least two merged dust components or a single dust component perturbed by planetary encounters.