  Among several methods for accurate measurements of solar diameter, there are
transits at fixed almucantarat used in solar astrolabes. The almucantarat is a
circle of given height. The horizon circle is the zero almucantarat, and data
from four sunsets on the Tyrrenian sea are discussed. The angular diameter of
the Sun is recovered with a few arcseconds accuracy using 60 fps video of
sunsets.
