. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi List of Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...

We report the detection of a 38 day period in the X-ray flux of the transient burster KS 1731-260 . The narrow peak of periodicity was detected during ∼TJD 10150–11050 when the source had a high and relatively stable X-ray flux. After ∼TJD 11100 the source became strongly variable on a time scale of months that contaminates the search for the 38 day periodicity. The detected period can not be a...