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Discrete wave packets at the proton cyclotron frequency at comet P/Halley

Neubauer, F. M.; Mazelle, C.

We present in this letter the first experimental evidence for wave packets near the local proton cyclotron frequency in the plasma environment of a comet. The observations have been made by the GIOTTO magnetometer experiment (MAG) around comet P/Halley on both sides of closest approach. The waves are always left-handed in the spacecraft frame, ell…

Pickup water group ions at comet Grigg-Skjellerup

Coates, A. J.; Winningham, J. D.; Borg, H. +9 more

The density and velocity distribution of cometary water group ions was measured by the Giotto spacecraft in the regions upstream and downstream of the ‘bow shock’ at comet Grigg-Skjellerup. The results show that the distributions of ions are ring-like until quite close to the shock, the timescales for pitch angle and energy diffusion appear simila…