X-RAY AND RADIO PULSE PHASE COMPARISON FOR PSR-1509 - 58

The measurement of the relative X-ray and radio pulse phase of rotation-powered pulsars can provide important information on the geometry of the magnetic field and on the physical conditions in the radiation generation regions. Contemporaneous observations of the pulsar PSR 1509-58 in X-rays with the Ginga satellite and at radio wavelengths with the Parkes radiotelescope have been used to determine this relative phase. This is the third measurement of the phase difference between the radio and high-energy pulses of a young pulsar, the others being the Crab and the Vela pulsars. We find that the radio pulse peak leads the X-ray peak by 37 +/- 3 ms or about one-quarter of the pulse period. In contrast to the two other pulsars, the X-ray emission is single-pulsed with a broad asymmetric pulse shape.