Brightness measurements at different solar phase angles have for long been one of the main sources of information constraining models of the surface micro-structure of Solar System bodies without atmospheres (Bowell et al. 1989; Hapke 1993). Despite the overwelmingly richer information content in the close-up disk-resolved space-probe images of Gaspra and Ida (Helfenstein et al. 1994 and 1996), broad phase curve surveys of many asteroids is still important in order to generalize to larger populations of minor bodies.
Previous surveys similar to this one have been published by Tedesco (1989), Lagerkvist & Magnusson (1990), and Lagerkvist et al. (1992). The last of these will be referred to as Paper I, and the current paper can be regarded as a follow-up to it, with presentation of more recent observations.
The physical interpretation of phase curves of asteroids typically are semi-empirical (Bowell et al. 1989; Hapke 1993). Theories usually predict the effect of roughness, porosity and scattering inside the surface material. The number of physical parameters involved is often quite large and there is no way that a single phase curve can give unambigous values for all. When the albedo of the asteroid is low and the scattering is geometric the theoretical interpretation gives good approximations.