The timing history of the microquasar XTE J1859+226 Original Research Article

We present an analysis of data of the black hole candidate and X-ray transient XTE J1859+226 taken with the Rossi X-ray Timing Explorer, covering the whole 1999 outburst of this source. We found three main different types of low-frequency QPOs with well-defined time-lags, coherence and intensity properties. Rapid transitions between different power spectral shapes were observed and their link with the count rate was studied. The frequency of the narrow 4.5–6 Hz type-B QPO was found to be linearly correlated with the count rate.