Observations of the 1996 Leonid meteor shower by radar, visual and video techniques

Abstract

The activity of the 1996 Leonid shower from two radars, global visual and single-station low-light-level TV (LLTV) observations is presented and summarized. Radar observations from Ondřejov in the Czech Republic indicate a peak rate of (>+1) Leonids near λ⊙ = 235°2±0.1 (Equinox 2000). As observed by this radar, this peak interval was characterized by a significant increase in the number of bright Leonids as demonstrated by a noticeable lowering of the mass index near the peak. From radar observations in Ontario, Canada (using the CLOVAR system), a raw peak flux of 1.3±0.3×10−2 meteoroid km−2 h−1 brighter than radio magnitude +7.7 was reached at λ⊙ = 235°3±0.1, uncorrected for initial train radius effects. Single-station LLTV observations suggest a peak shower flux of 1.8±0.4×10−2 meteoroid km−2 h−1 brighter than absolute magnitude +5±0.5 between 235°3 and 235°39. The position of the radiant on the night of maximum of the shower is found to be α=152°9±1°0 and δ=22°1±1°0 from CLOVAR observations and α=153°3±1°7 and δ=22°1±1°7 from LLTV observations. Visual observations of the shower yield a peak zenithal hourly rate (ZHR) of 86±22 at 235°17±0°07 or an equivalent flux of 1.2±0.4×10−2 meteoroid km−2 h−1 brighter than absolute visual magnitude +6.5. The visual peak was short-lived (1.5 ± 0.5 h HWHM) and richer in fainter meteors than neighbouring intervals. Discrepancies in the estimated absolute Leonid flux found using differing methods are noted and possible reasons for the differences discussed. The stream in 1996 showed two distinct meteoroid populations: a population of recently ejected meteoroids rich in smaller particles near 235°17 which is very narrow in nodal extent (HWHM 0°07±0°02), and an older component (of order 10 revolutions in age) peaking near 235°4 which is rich in larger stream meteoroids, of long duration (FWHM 1°2 ±0°4), which contributed most to the total mass flux at Earth from the stream in 1996.