Comparative study opposition effect of icy solar system objects

Opposition effect is a nonlinear increase in the brightness of an object cl ose to astronomical opposition. We present a comparison and summary of the phase curves of some icy solar system objects, and terrestrial ice. We have constructed a method of approximating the height and width of the oppositi on peak and evaluating the practicality of the method in each case, with th e aid of a four-parameter fit to a linear-exponential function and computin g the a posteriori probability distribution of the height and width of the opposition peak. The procedure described is most applicable in finding a re alistic fit and evaluating the suitability of data, even with moderate inac curacy. We have studied the effect of the number of data points to the feas ibility of the fit, in order to estimate the minimum amount of data require d for a desired accuracy. Furthermore, we present an interpretation of the phase curves by means of two scattering mechanisms with important applicati ons to the recent study of the opposition effect: shadowing and coherent ba ckscattering. (C) 2001 Elsevier Science Ltd. All rights reserved.