Intensity dependence of the pulse profile and polarization of the VELA pulsar.

Polarization measurements of the Vela pulsar PSR 0833-45 at 2295 MHz revealed that the radio pulse profile is composed of four components. The four component configuration was found to fit the observed dependence of the pulse profile on the intensity of the pulsar, and the dependence of the modulation index and power spectrum of the intensity fluctuations on the pulse-longitude. Deviations of the observed polarization position angles from those predicted by a rotating vector model were explained by the emission regions for each component being located at different distances from the star. The components are affected by retardation, aberration, and magnetic field curvature effects, all of which contribute to arrival of the components at different longitudes even though the components actually carry the position angle signature predicted by the rotating vector model.