Scatter broadening of pulsars in the direction of the Gum nebula

We have measured the scatter broadening of pulsars in the direction of the Gum nebula. For the first time, our observations show clear variations of scattering properties across the Gum nebula. The IRAS-Vela shell is shown to be a high scattering region. Our revised estimations of distances to these pulsars are consistently less by a factor of 2-3, which has very important consequences for the deduced values of radio luminosity and transverse velocity of pulsars.