Further Ginga Observations of PSR B0540−69

Abstract

We report the pulse-timing history of PSR B0540-69, based on allapplicable data from the Ginga X-ray observatory. Using these data,together with other, overlapping optical and X-ray observations, we havedetermined an improved value for the braking index, n=2.080, as wellas a new estimate for the celestial position of PSR B0540-69. Ourresults are based on an analysis of local pulse frequencies, using amethodology designed to efficiently utilize the sparsely sampledobservations of PSR B0540-69. This strategy rests on iterativelydetermining a sequence of successively more precise pulse ephemerides fromsuccessively more precise estimates of local pulse frequencies. We alsopresent improved X-ray and optical pulse profiles and evidence for aclose alignment between profiles in these two energy regimes. We mayhave detected a small, Crab-like glitch in the pulse frequency ofthis pulsar in a reanalysis of previously published optical data.