Mutual phenomena of Jovian satellites

Abstract

Mutual eclipses of Galilean satellites were observed and the results are given. The observations are fitted by utilizing Lambert's law, theoretical models assuming a uniform disk, and Lommel-Seeliger's law which describes the scattering characteristics of the eclipsed satellite's surface. Marquardt's algorithm is employed to fit light curves from two observed events and three published light curves with theoretical light curves. Lommel-Seeliger's law, used to describe surface scattering on Io and Europa, results in the best fitting. The theoretical light curve is shifted in the direction of the relative motion of the eclipsed satellite by means of a shift parameter which is determined with the impact parameter. The shift parameter can be used as a measure of the phase correction when asymmetric light curves are encountered. The observed mid times of all but one of the events are shown to be near the predicted times.