  We have obtained exposures of the field of X0512-401 in the globular cluster
NGC1851, in X-rays with the Chandra X-ray Observatory, and in the far-UV with
the Hubble Space Telescope. We derive an accurate new X-ray position within ~1"
for X0512-401, which enables us to confirm that the only plausible candidate
for the optical/UV counterpart is the Star A, which we previously identified
from WFPC2 imaging. We find no evidence for X-ray or UV flux modulation on the
ultra-short (<1 hr) expected binary period, which implies a low system
inclination. In addition, we have detected and spatially resolved an X-ray
burst event, confirming the association of the burster, quiescent X-ray source,
and optical object. The very large Lx/Lopt of this object implies an
extraordinarily compact system, similar to the sources in NGC6624 and NGC6712.
