Circinus X-1 observations with HEAO A-1.

Scanning observations of Cir X-1 with the HEAO A-1 experiment are reported, and a search for periodic pulsations is carried out. It is found that a random distribution of burst times fails to provide a good fit to the distribution of intervals between bursts and that strict periodicity does not fit the observed intensity variations. An alternative interpretation is discussed according to which there is a characteristic delay following one burst before another can occur; this sometimes gives the appearance of periodicity in short data samples.