Visual observations of the Perseid meteor shower 1988–1994

Abstract

Visual meteor observations are used to determine the flux profile of the Perseid stream from 1988 to 1994. The position and peak flux of recently detected outburst maxima are found for each year as is the location and magnitude of the regular maximum. The Perseid stream is found to consist of three primary components; a long-lived and relatively weak background component, a core component which is active for 1–2 days near the main peak of the shower and an outburst component which is active for only a few hours. The outburst peaks show a systematic variation in terms of the solar longitudes of the peak. The position of the outburst shifted backwards in solar longitude (J2000.0) from λ ⊙ = 139°.78 in 1988 to λ ⊙ = 139°.48 in 1992, when it occurred closest to the node of 109P/Swift-Tuttle (139°.44). In subsequent years the peak position shifted forward again to λ ⊙ = 139°.59 in 1994. The magnitude of the peak flux shows a significant difference between returns before 1991 as compared to those after this year. This may indicate an ejection origin other than 1862 for outburst material encountered before 1991. The particle composition of the outburst maximum and core maximum are indistinguishable. A double maximum in the population index associated with these activity maxima has been detected in the average Perseid profile. High temporal resolution study of the flux profile of the ascending branches of the outburst profiles in 1993 and 1994 suggest that this component may consist of sub-components, possibly of differing ages.