Spectral and timing properties of the X-ray emission from the millisecond pulsar PSR B1821-24

. We report results on the timing and spectral analysis of observations of the millisecond pulsar PSR B1821 − 24 with RXTE, BeppoSAX and Chandra. The X-ray light curve is characterized by two narrow peaks at a phase distance of 0 . 452 ± 0 . 002. The average pulsed emission, over the range 1.6–20 keV, is well repre-sented by a single power law with a photon index α = 1 . 30 − 0 . 02 +0 . 05 and unabsorbed (2–10 keV) pulsed X-ray flux of 3 . 9 × 10 − 13 erg cm − 2 s − 1 . We searched for a possible bunching of X-ray photons to verify if the X ray emission has a time structure similar to that of giant pulses and found a negative result. - X-rays: stars