Further Ginga Observations of PSR B0540−69

Abstract

We report the pulse-timing history of PSR B0540[69, based on all applicable data from the Ginga X-ray observatory. Using these data, together with other, overlapping optical and X-ray observations, we have determined an improved value for the braking index, n \ 2.080, as well as a new estimate for the celestial position of PSR B0540[69. Our results are based on an analysis of local pulse frequencies, using a methodology designed to efficiently utilize the sparsely sampled observations of PSR B0540[69. This strategy rests on iteratively determining a sequence of successively more precise pulse ephemerides from successively more precise estimates of local pulse frequencies. We also present improved X-ray and optical pulse proÐles and evidence for a close alignment between proÐles in these two energy regimes. We may have detected a small, Crab-like glitch in the pulse frequency of this pulsar in a reanalysis of previously published optical data.