Measurement of the proper motion of Vela with the LBA

The first accurate measurements of Vela's proper motion were produced using the Parkes-Tidbinbilla Interferometer (PTI) (Bailes et al 1989). This 275 km baseline at 1.6 GHz gave a resolution of 140 mas and detected the proper motion and thus, by extrapolation, the birth site. We have extended this work to allow the third dimension to be derived via the parallax. We find the offset between the spin axis and the proper motion vector to be $9^o$, which limits acceleration time from the SN blast.