Milliarcsecond Astrometry for the Galilean Moons Using Stellar Occultations

Abstract A stellar occultation occurs when a Solar System object passes in front of star for an observer. This technique allows the sizes and shapes occulting body to be determined with kilometer precision. In addition, this constrains body’s positions, albedos, densities, so on. context Galilean moons, these events can provide their best ground-based astrometry, uncertainties order 1 mas (∼3 km at Jupiter’s distance during opposition). We organized campaigns successfully observed by Io (JI) 2021, one Ganymede (JIII) 2020, Europa (JII) 2019, stations North South America. also re-analyzed two previously published events: 2016 another 2017. then fit known 3D shape satellite determine its center figure. resulted astrometric positions milliarcsecond level. The obtained from occultations used together dynamical models ensure highly accurate orbits moons. These help planning future space probes aiming Jovian system, such as JUICE ESA Clipper NASA. They allow more efficient flyby maneuvers.