Properties of the 2 - 6 keV pulse profiles of Hercules X-1.

We have reanalyzed Uhuru data of 2-6 keV X-ray pulsations from Hercules X-1 during three high states of the source. We find that the pulse amplitude and pulsed fraction vary systematically with 1.7 day orbital phase and with phase in the 35 day high-low cycle of the source. However, the shapes of the pulsations otherwise show little variation with time, and the intensity of unpulsed X-rays does not vary greatly during most of each high state. From Monte Carlo simulations of the data, we find that the observations are consistent with no pulse-to-pulse shape fluctuations and with small but nonzero extrastatistical intensity fluctuations on time scales between 0.1 and 10 s. Our results support models wherein the 35 day cycle is due to variable obscuration of the X-ray star by a wobbling accretion disk. Subject headings: X-rays: binaries - X-rays: sources