Kilo-Hertz QPO and X-ray bursts in 4U 1608-52 in low intensity state

We present the results from RXTE/PCA observations of 4U 1608-52 in its island state on March 15, 18 and 22 of 1996. Three type I X-ray bursts were detected in one RXTE orbit on March 22. We observed QPO features peaking at 567–800 Hz on March 15 and 22, with source fractional rms amplitude of 13%–17% and widths of 78–180 Hz in the power density spectra averaged over each spacecraft orbit. The rms amplitudes of these QPOs are positively correlated with the photon energy. The three X-ray bursts, with burst intervals of 16 and 8 minutes, have a duration of 16s. The blackbody emission region of the smallest X-ray burst among the three suggest it was a local nuclear burning. We also discuss a type I X-ray burst candidate in the observation.