Crab Pulsar timing 1982-87

Abstract

We present observations of the arrival times of pulses from the pulsar in the Crab Nebula over a six-year interval. The data are intended to permit the investigation of the interior of the neutron star through the study of glitches and timing noise and to provide an ephemeris for high-energy observations. The first and second frequency derivatives provide a value for the braking index of |$n=2.509\pm0.001$|⁠, which is consistent with previous observations. The third frequency derivative can now be determined over an 18-yr span and is as expected for this braking index. The predominant deviations from a simple slow-down model form a sinusoid with a period of 20 months, attributable to an oscillation of the bulk of the neutron superfluid in the pulsar. One conspicuous glitch occurred in 1986 August, and the subsequent recovery was studied from only one hour after the event.