Initial low/hard state, multiple jet ejections and X-ray/radio correlations during the outburst of XTE J1859+226

We have studied the 1999 soft X-ray transient outburst of XTE J1859+226 at radio and X-ray wavelengths. The event was characterized by strong variability in the disc, corona and jet — in particular, a number of radio flares (ejections) took place and seemed well-correlated with hard X-ray events. Apparently unusual for the canonical‘soft’ X-ray transient, there was an initial period of low/hard state behaviour during the rise from quiescence but prior to the peak of the main outburst — we show that not only could this initial low/hard state be a ubiquitous feature of soft X-ray transient outbursts, but also it could be extremely important in our study of outburst mechanisms.