Misura del diametro solare ad almucantarat zero
  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. 
Costantino Sigismondi
astro-ph.IM physics.optics