THE OPTICAL COUNTERPART OF THE SUPERSOFT SMALL MAGELLANIC CLOUD TRANSIENT PULSAR RXJ50059.2-7138

We identify the probable optical counterpart of the Small Magellanic C loud (SMC) supersoft source RX J0059.2-7138 with a similar to 14th-mag nitude star lying within the X-ray error circle. We present high-resol ution optical spectroscopy, which reveals strong H I emission and He I absorption, indicative of a Be star. This classification is consisten t with the colours that we derive from optical photometry. We thus fin d evidence to support the existing tentative identification of this ob ject as a Be/X-ray binary, the first of its kind to exhibit luminous s upersoft X-ray emission.