Optical observations of NEA 3200 Phaethon (1983 TB) during the 2017 apparition

TL;DR

This study presents detailed optical observations and shape modeling of NEA 3200 Phaethon during 2017, refining its rotational and pole orientation parameters using multiple telescopes and advanced inversion techniques.

Contribution

It provides new convex and non-convex shape models and precise spin and pole orientation data for Phaethon based on extensive optical observations and inversion methods.

Findings

Rotational period of 3.6039 hours determined

Pole orientation at (308, -52) and (322, -40) degrees

Non-convex shape model with concavity features

Abstract

The near-Earth asteroid 3200 Phaethon (1983 TB) is an attractive object not only from a scientific viewpoint but also because of JAXA's DESTINY+ target. The rotational lightcurve and spin properties were investigated based on the data obtained in the ground-based observation campaign of Phaethon. We aim to refine the lightcurves and shape model of Phaethon using all available lightcurve datasets obtained via optical observation, as well as our time-series observation data from the 2017 apparition. Using eight 1-2-m telescopes and an optical imager, we acquired the optical lightcurves and derived the spin parameters of Phaethon. We applied the lightcurve inversion method and SAGE algorithm to deduce the convex and non-convex shape model and pole orientations. We analysed the optical lightcurve of Phaethon and derived a synodic and a sidereal rotational period of 3.6039 h, with an axis ratio of a/b = 1.07. The ecliptic longitude (lambda) and latitude (beta) of the pole orientation were determined as (308, -52) and (322, -40) via two independent methods. A non-convex model from the SAGE method, which exhibits a concavity feature, is also presented.