A state transition of GX 339-4 observed with RXTE

We report the results of observations with the Rossi X-ray Timing Explorer of the black-hole candidate GX 339-4 during the state transition of 1998. We find that both the X-ray spectrum and the characteristic of the time variability after the transition are typical of a high/soft state. We cannot exclude that the source went through an Intermediate State before entering the high state. We discuss the results and compare them with other known black hole candidates.