Asteroid phase function parameters and taxonomic constraints from the Zwicky Transient Facility

ABSTRACT We derive the asteroid phase curves from photometry acquired by the Zwicky Transit Facility (ZTF). Using phase-curve modelling, we estimate the absolute magnitudes and slope parameters of 35 073 phase curves of about fifty-six thousand asteroids, including 179 Near-Earth Asteroids, 32 451 main-belt asteroids, 107 Jupiter Trojan, and ten centaurs. The probabilities of C and S complex membership are calculated for each asteroid using the phase function parameters for those asteroids whose taxonomic types have been determined by independent photometric and spectroscopic observations. The taxonomic classification of asteroids of an unknown taxonomic type can then be estimated on the basis of their phase function parameters, taking advantage of the association between the phase function parameters and the taxonomic type. The taxonomic distribution throughout the main belt consists of a general view of the S/C complex ratios as they decrease towards the outer main belt. The distributions of the G1 and G2 values in known asteroid families are given and the taxonomies of 18 individual families are derived. The size distribution is shown with the heliocentric distance. The power law derived from the cumulative size distribution is consistent with that obtained in other surveys.