Minor planets and related objects. XXVIII. Asteroid magnitudes and phase relations.

A compilation of absolute magnitudes, B(l,0), based on an average phase coefficient of 0.039 mag/deg is presented. Observed phase coefficients PB are used for the 60 asteroids for which they are available. A slightly improved correction to magnitudes observed within the opposi- tion effect is also used for the first time. Significant numbers of new photoelectric observations by E. Bowell, and others, are included. The listing is now mostly based on photoelectric magnitudes and those from the photographic Palomar-Leiden and Yerkes-McDonald surveys.