6 - Planetary Disk-Integrated Photometry

Summary

An overview of the methods used to extract information about planetary objects from disk-integration (telescopic) observations. The primary relationship between planetary size, albedo, and absolute magnitude is derived. Complications in this relationship for comets and irregular asteroids are discussed, including the characterization of lightcurves. The planetary phase curve is of fundamental importance in disk-integrated work and its construction and use is described. Again, comets and asteroids have more complicated phase curves and these complications are described, along with the modern HG magnitude system for asteroids and its origin. The polarization properties of small bodies provide additional physical information, especially when cast into the form of a polarization phase curve, and the empirical relations that have been gleaned from extensive laboratory work are introduced, along with their application to asteroid and comet studies. Finally, a recent published application of these principles to the study of Mercury is examined.