Pulsar magnetospheres are geometrically simple, and observables are largely determined by two unknown parameters: ζ(α), the observer’s (magnetic dipole axis’) inclination to the pulsar’s spin axis. By exploiting the tendency for radiation to be beamed along magnetic field lines, gamma-ray light curves can be used to infer the position and extent of the emitting volume. However, degeneracy with ζ and α prevents a unique determination.
This degeneracy can be broken—or at least ameliorated—by applying constraints on α and ζ obtained from radio polarimetry. To support the search for gamma-ray pulsars, the Parkes radio telescope has performed monthly timing observations of 160 high Edot pulsars for nearly 5 years. Co-added, these data yield high signal-to-noise, calibrated polarimetry. We present the constraints obtained from a uniform analysis of the polarimetry and discuss the implications for the population and for particularly well-constrained pulsars.