We have obtained exposures of the field of X 0512-401 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 \sim 1″ ) for X 0512-401 , 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 ( \lesssim 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 L _ { X } / L _ { opt } of this object implies an extraordinarily compact system , similar to the sources in NGC6624 and NGC6712 .