Very Long Baseline Array Measurement of Nine Pulsar Parallaxes

Abstract

We determined the distances to nine pulsars by parallax measurements using the NRAO Very Long Baseline Array, doubling the number of pulsars with accurate distance measurements. Broadband phase modeling was used to calibrate the varying dispersive effects of the ionosphere and remove the resulting phase errors from the phase-referenced VLBI data. The resulting parallaxes have a typical accuracy of 100 μas or better, yielding distance measurements as accurate as 2%. We also report new proper motion measurements of these pulsars, accurate to 400 μas yr-1 or better.