Daily observations of a large period jump of the Vela pulsar

Observations are presented of pulse arrival times for the Vela pulsar PSR0833-45, recorded for 5 hr per day at Hobart and at approximately weekly intervals at the NASA Deep Space Station at Tidbinbilla, following a pulse period reduction of about 102 ns during 10-11 October 1981. The recovery from this period pulse is shown to be accurately described by a model consisting of the sum of two exponential decays with time constants respectively 1.62 +- 0.18 days and 233 +- 1 days. The slower decay is consistent with the two-component neutron star model and has similar parameters to previously observed jumps for this pulsar. However, the rapid initial decay may indicate the presence of a third component which is tightly coupled to the neutron star crust. (U.K.)