Published online by Cambridge University Press: 27 February 2018
We have modelled the evolution in the distribution of orbits of 1.5 x 106 particles released at the 1862, 1737 and 1610 apparitions of 109P/Swift-Tuttle for a range of particle masses and for a range of ejection angles about the comet-solar line. The evolution of the stream is dominated by the influence of planetary perturbations, most notably those due to Jupiter. A periodicity of approximately 12 years in Perseid activity is noted in the material ejected during the 1862 apparition. Without Jovian perturbations, the nodes of these recently released Perseid particles would not cross the Earth's orbit. Activity from 1862 is notable in the simulations for 1991-1994 and also for the early 1980's. Ejections in 1737 and to a lesser extent in 1610 contribute material seen at the Earth in the late 1980's.