  Imaging Atmospheric Cherenkov Telescopes (IACTs) are very-large telescopes
designed to detect the nanosecond-timescale flashes produced within extended
air showers. Because IACTs are sensitive to the Cherenkov light (UV/blue) and
use photodetectors with extremely fast time responses, they are also able to
perform simultaneous optical observations. The large reflecting areas of these
telescopes (larger than 100 m$^2$) makes them well-suited to studying fast
optical transient phenomena with timescales ranging from seconds to
milliseconds to nanoseconds, and the unique optical design provides a wide
field of view monitoring capability with a modest point spread function.
VERITAS, with its recently upgraded PMT current monitoring instrumentation, was
able to provide the first detection of asteroid occultations with an IACT,
resulting in the highest angular resolution measurements for stellar diameters
ever taken in the visible band range. Here we explore the feasibility of using
this technique to significantly expand the number of stars with directly
measured stellar radii, usable for population studies to test stellar evolution
modelling or transiting exoplanet radius measurements. A single observatory
with a high-speed visible-band photometer with a sensitivity reaching the
13$^{th}$ magnitude could increase the number of directly measured K stars
diameters by 50%.
