Interpretation of the IAU Two-Parameter Magnitude System for Asteroids in Terms of Hapke Photometric Theory

In 1985 IAU Commission 20 adopted a two-parameter magnitude system for asteroids (Marsden, B. G. 1986, Minor Planet Circulars 10193 and 10194; Bowell, E., et al. 1989, in Asteroids II (R. P. Binzel, T. Gehrels, and M. S. Matthews, Eds.), pp. 524-556, Univ. of Arizona Press, Tucson) based upon the application of the Lumme-Bowell photometric model (Lumme, K., and E. Bowell 1981, Astron. J. 86, 1694-1704) to asteroid phase curves. The Hapke photometric theory (Hapke, B. 1986, Icarus 67, 264-280) has been applied extensively to spacecraft and telescopic observations of a multitude of objects throughout the Solar System to derive their physical and optical surface characteristics. We have derived a conversion from the Lumme-Bowell-based parameters to those used in the Hapke photometric model to facilitate comparison of asteroid regoliths to those found elsewhere in the Solar System.