In the course of a programme to study optical pulsars, we have observed at different occasions PSR0540-69, the 50 msec pulsar in the LMC. Like the Crab pulsar, it has been detected at X-rays, optical and radio and its braking index (∼2) determined. In this communication we report some results obtained on this pulsar, in particular the presence of narrow features in the pulse profile and compare it with a nearly simultaneous X-ray observation.

The observations were carried out at the 3.6m telescope at La. Silla observatory, Chile. The instrument consisted on a single channel photometer coupled with a. photomultiplier (GaAs photocathode). The sampling frequency was 10 kHz and the output of the photon counting system was recorded sequentially on magnetic tape. A set of filters and diaphragms were available. A standard analysis was then performed. After corrections to the solar system barycenter, the data were analyzed and the best period determined using the test (Buccheri et al, 1983).