The 1997 hard-state outburst of the X-ray transient GS 1354-64/BW Cir

We present observations of the 1997 outburst of the X-ray transient GS 1354 -64 (BW Cir) at X-ray, optical and, for the first time, radio wavelengths; our results include upper limits to the linear and circular polarization fo r the radio data. The X-ray outburst was unusual in that the source remaine d in the low/hard X-ray state throughout; the X-ray peak was also preceded by at least one optical outburst, suggesting that it was an 'outside-in' ou tburst similar to those observed in dwarf novae systems, although possibly taking place on a viscous time-scale in this case. It therefore indicates t hat the optical emission was not dominated by the reprocessing of X-rays, b ut that instead we see the instability directly. While the radio source was too faint to detect any extended structure, spectral analysis of the radio data and a comparison with other similar systems suggest that mass ejectio ns, probably in the form of a jet, took place and that the emitted synchrot ron spectrum may have extended as far as infrared wavelengths. Finally, we compare this 1997 outburst of GS 1354-64 with possible previous outbursts a nd also with other hard-state objects, both transient and persistent. It ap pears that a set of characteristics-such as a weak, flat-spectrum radio jet , a mHz QPO increasing in frequency, a surprisingly high optical/X-ray lumi nosity ratio, and the observed optical peak preceding the X-ray peak-may be common to all hard-state X-ray transients.