The X{ray Spectrum of the Plerionic System Psr B1509?58/msh 15?52

We present the results of observations of the PSR B1509?58/MSH 15?52 system in X{rays (2 ? 250 keV) by the Rossi X{ray Timing Explorer. The spectra of the peak of the pulsed component (radio phase 0:17 ? 0:53) is t by a power law of photon index 1:360:01, with no evidence of a high energy spectral break seen up to 200 keV. For the oo-pulse spectral component, the spectrum from 2 ? 250 keV is t by a power law of photon index 2:215 0:005. An iron emission line at 6:7 keV with an equivalent width of 129 eV improves the t, but only at a marginal signiicance. Thermal bremsstrahlung and Raymond-Smith models produce much worse ts to the unpulsed data. The lack of a high energy spectral break in the pulsed emission implies an eeciency of 3% in the conversion of pulsar spindown energy to pulsed X{rays in the system.