The cycle-to-cycle variability of Cygnus X-3.

Results are reported of a study of the variability of the shape of the light curve of Cyg X-3 from one cycle to the next on time scales down to about 200 s. Variations occur mainly around the maximum of the light curve, on a time scale of about half an hour or less, and give rise to a dispersion of the individual light curves around the mean which is a considerable fraction of the amplitude of the modulation.