An EXOSAT observation of the bursting X-ray transient 4U 1608-52

An EXOSAT observation of the transient X-ray burster 4U 1608-52 detected the source in a low state. The spectrum of the persistent emission is a power law with a photon index of 1.9 similar to that from other X-ray burst sources. During the 5.5 hr exposure a double-peaked type I burst was seen. A detailed spectral analysis shows this to be caused by changes in the colour temperature rather than radius expansion. Power spectra of the time resolved data show increasing power towards low frequencies (red noise) and a broad peak at ∼ 0.3 Hz with a significance of ∼ 3σ, that may indicate the presence of quasi-periodic oscillations. (author)