Diffraction modelling of a 2023 March 5 stellar occultation by subkilometer-sized asteroid (98943) 2001 CC21

Abstract

We present an analysis of a stellar occultation event caused by a near-Earth asteroid (98943) 2001 CC21, an upcoming flyby target in the Hayabusa2 extended mission, on 2023 March 5. To determine the asteroid’s shape from diffraction-affected light curves accurately, we developed a novel data-reduction technique named the Diffracted Occultation’s United Simulator for Highly Informative Transient Explorations (DOUSHITE). Using DOUSHITE-generated synthetic models, we derived constraints on (98943) 2001 CC21’s shadow shape from the single-chord occultation data. Our results suggest a significant elongation of the shadow with an axis ratio of b/a = 0.37 ± 0.09. This shape could be crucial for planning Hayabusa2’s high-speed flyby to optimise the limited imaging opportunities.