# Arecibo Radar Observations of Near-Earth Asteroid (3200) Phaethon During the 2017 Apparition

## TL;DR

This study presents detailed radar imaging of near-Earth asteroid Phaethon during its 2017 close approach, revealing a spheroidal shape with surface features, and compares it to other well-studied asteroids.

## Contribution

First detailed radar imaging of Phaethon during its 2017 apparition, revealing surface features and shape characteristics similar to other known near-Earth asteroids.

## Key findings

- Phaethon is roughly spheroidal, over 6 km in diameter.
- Surface features include a possible crater and a radar-dark pole region.
- No satellites or dust coma detected during observations.

## Abstract

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$^{\circ}$ 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.