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The Vavilov-Cerenkov Effect and the Doppler Effect in the Motion of Sources with Superluminal Velocity in VacuumIt is customary to consider only ``subluminal'' light sources, or sources moving with a velocity v lower than the velocity of light in vacuum (c). It is assumed in this connection that the Vavilov--Cerenkov effect and the anomalous Doppler effect are possible only in media and waves for which the refractive index n(ω)>1. For this reason, the phase velocity of the waves is cph=[c/n(ω)]cph. Yet, as is well known, there exist also ``superluminal'' sources, with velocity v>c. Examples are light spots produced on a remote screen by a rotating source of light or particles. The spot velocity is v=ΩR, where Ω is the angular velocity of source rotation and R is the distance to the screen. The condition v>c can be realized on the Earth, and is practically always realized under astronomical conditions for pulsar radiation. It is emphasized in the article that superluminal sources are equivalent in a wide range to subluminal ones, and, concretely, can generate Cerenkov radiation in vacuum and in a medium with $n(\omega)
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