  The University of Sydney has a long history in optical stellar
interferometry. The first project, in the 1960s, was the Narrabri Stellar
Intensity Interferometer, which measured the angular diameters of 32 hot stars
and established the temperature scale for spectral classes O - F. That
instrument was followed by the Sydney University Stellar Interferometer (SUSI),
which is now undergoing a third-generation upgrade, to use the multi-wavelength
PAVO beam combiner. SUSI operates at visible rather than IR wavelengths and has
baselines up to 160 m, so it is well suited to the study of hot stars. A number
of studies have been carried out, and more are planned when commissioning of
the PAVO system is complete. Conversion of the system to allow remote operation
will allow larger scientific projects to be undertaken.

Instrumentation and Methods for Astrophysics;Solar and Stellar Astrophysics