No abstract

We present the first measurements of the radiant and orbit of meteoroids that are part of the unusual Perseid activity called the ‘Perseid Filament’. This filament was encountered by Earth in the years before and after the return of the comet to perihelion in December of 1992. Between 1989 and 1996, there were brief meteor outbursts of near‐constant duration with a symmetric activity profile. In 1993, however, rates increased more gradually to the peak. That gradual increase is identified here as a separate dust component, which we call the ‘Nodal Blanket’. We find that the Nodal Blanket has a very small radiant dispersion. On the other hand, the Perseid Filament has a radiant that is significantly dispersed and systematically displaced by 0.3°. This dispersion implies that unusually high ejection velocities or planetary perturbations must have had time to disperse the stream. In both cases, one would expect a rapid dispersion of matter along the comet orbit. In order to explain the concentration of dust near the comet position, we propose a novel scenario involving long‐term accumulation in combination with protection of the region near the comet against close encounters with Jupiter due to librations of the comet orbit around the 1:11 mean‐motion resonance.

Abstract. 359 precisely reduced meteor orbits are presented that are the result of the Dutch Meteor Society's Photographic Meteor Survey in the period 1981 until 1993. Orbits include those of major and minor showers, doubling the number of known precise orbits of some meteor streams. From the spread in solutions of all possible sets of two photographic stations, we derive the measurement uncertainties from which we are able to calculate the intrinsic scatter in the Perseid meteor stream. The new Geminid orbits are compared to those obtained in similar surveys in the 1950's. This first measurement of the rate of change of Geminid orbits over time agrees well with model predictions.

No abstract

No abstract