We report Arecibo S-band (2380 MHz; 12.6 cm) radar observations of near-Earth asteroid (3200) Phaethon during the December 2017 apparition when Phaethon passed within 0.07 au of Earth. Radar images with a resolution of 75 m per pixel reveal a roughly spheroidal shape more than 6 km in diameter at the equator with several discernible surface features hundreds of meters in extent. These include a possible crater more than 1 km across located below 30∘ latitude and a roughly 600-m radar-dark region near one of the poles. Overall, the radar images of Phaethon are reminiscent of those of (101955) Bennu, target of the OSIRIS-REx mission. As such, the shape of Phaethon is suspected to have an equatorial ridge similar to the top-shaped models of several other radar-observed near-Earth asteroids as well as the optical images of (162173) Ryugu returned by the Hayabusa2 spacecraft. Preliminary analysis of the radar data finds no satellites and gives no indication of a dusty coma at the time of these observations.
@article{arxiv.1902.00969,
title = {Arecibo Radar Observations of Near-Earth Asteroid (3200) Phaethon During the 2017 Apparition},
author = {Patrick A. Taylor and Edgard G. Rivera-Valentin and Lance A. M. Benner and Sean E. Marshall and Anne K. Virkki and Flaviane C. F. Venditti and Luisa F. Zambrano-Marin and Sriram S. Bhiravarasu and Betzaida Aponte-Hernandez and Carolina Rodriguez Sanchez-Vahamonde and Jon D. Giorgini},
journal= {arXiv preprint arXiv:1902.00969},
year = {2019}
}
Comments
16 pages, 2 tables, 5 figures, accepted to Planetary and Space Sciences special issue on Phaethon and Meteoroids