  Using results from radio and X-ray observations of millisecond pulsars in 47
Tucanae, and extensive HST U, V, I imaging of the globular cluster core, we
have derived a common astrometric solution good to < 0.1". A close positional
coincidence is found for 47 Tuc U, a 4.3 ms pulsar in a 0.429 day orbit,
detected in radio and X-rays, with an m_V = 20.9 blue star. Analysis of
extensive time series data for this optical candidate shows a 0.004 magnitude
semi-amplitude variation at the period and phase expected from the radio
ephemeris, and the optical variations are spatially coincident with the
candidate. This provides secure optical detection of the white dwarf companion
to the millisecond pulsar, the first such detection in a globular cluster,
allowing for comparisons to recent models for such companions with dependencies
on mass and age.
