Timing and spectral properties of PSR B0540-69 observed with BeppoSAX

BeppoSAX observed PSR B0540-69 on 1996 October 25-26 during the Science Ver ification Phase. The pulsar, detected by the imaging LEGS and MECS instrume nts (0.1-10 keV), shows a characteristic nearly sinusoidal pulse structure with a minor structure on the left side of the maximum. By combining the Be ppoSAX measurements with earlier ASCA results we derived a low value of the braking index of 2.10 +/- 0.10. We also investigate the X-ray spectral dis tribution of the pulsed emission in the energy band (2-10) keV. We find tha t it can be well represented by a single absorbed power-law with energy ind ex of 0.76 +/- 0.14 and N-H = (3.6 +/- 0.7) x 10(21) cm(-2).