Prediction and Observation of a Stellar Occultation by Haumea’s Satellite Namaka

Abstract Stellar occultations are an ideal way to characterize the physical and orbital properties of trans-Neptunian binary systems. In this research note, we detail the prediction and observation of a stellar occultation observed with NASA’s Infrared Telescope Facility on 2025 March 16th (UT), with drop-outs from both the dwarf planet Haumea and its smaller satellite Namaka. This occultation places a lower limit of 83 ± 2 km on Namaka’s diameter. We also discuss the possibility that this detection could help to constrain the orbit of Namaka, measure Haumea’s gravitational harmonics, and provide a path to measuring the internal structure of Haumea.