  The diameter of the Sun has been measured using Baily's beads during central
eclipses, observed with portable telescopes. A blend of tiny emission lines
produced in the first several hundred kilometers above the photosphere gives a
light signal which prolonges the light curves of the beads. The simple
criterion of light OFF/ON adopted in the previous approaches to define the
timing of photosphere's disappearance/reappearance is modified. The technique
of the limb darkening function reconstruction from the Baily's beads light
curves is introduced here.
