Daytime Seeing and Solar Limb Positions

Abstract

A method to measure the seeing from video made during drift-scan solar transits is proposed. The limb of the Sun is projected over a regular grid evenly spaced. The temporal dispersion of the time intervals among the contacts between solar limb and grid's rows is proportional to the atmospheric seeing. Seeing effects on the position of the inflexion point of the limb's luminosity profile are calculated numerically with Fast Fourier Transform. Observational examples from Locarno and Paris Observatories are presented to show the asymmetric contributions of the seeing at the beginning and the end of each drift-scan transit.