RXTE observations of cyg X-3

Abstract

Timing data analysis of the bright X-ray source Cyg X-3 based on RXTE/PCA was presented. The observations were carried out in August 1996 and February 1997. All observations showed the 4.h8 modulation due to the orbital period of the system with count rate ranging from ~ 900 to ~ 6000 cnt s-1. Almost all power spectra, the most sensitive timing results of Cyg X-3, may be well explained by pure Poisson noise above ~ 0.2 Hz and a power-law below ~ 0.2 Hz. During the February 1997, when the source was brightest in one part of the observations, it showed a temporary flickering-like behaviour with a period of ~ 70 s. A detailed study of the timing properties of Cyg X-3 as a function of count rate, orbital phase and photon energy was presented. The flickering-like behaviour seemed to be a dominant effect in describing the level and shape of the power spectra below (<~ 0.2 Hz).