2003A&A...410L...9C

We present timing and spectral results of PSR B1937+21, the fastest known millisecond pulsar (P≃1.56ms), observed with RXTE. The pulse profile, detected up to ∼20keV, shows a double peak with the main component much stronger than the other. The peak phase separation is 0.526±0.002 and the pulsed spectrum over the energy range 2-25keV is well described by a power law with a photon index equal to 1.14±0.07. We find that the X-ray pulses are closely aligned in phase with the giant pulses observed in the radio band. This results suggest that giant radio pulses and X-ray pulses originate in the same region of the magnetosphere due to a high and fluctuating electron density that occasionally emits coherently in the radio band. The X-ray events, however, do not show any clustering in time indicating that no X-ray flares are produced.