EGUsphere EGUsphere EGUsphere EGUsphere Copernicus Publications Göttingen, Germany 10.5194/egusphere-2026-2064 Juice/SWI during the Lunar-Earth-Gravity-Assist (LEGA). IV. Antenna pointing and beam characterisation Moreno Raphael https://orcid.org/0000-0002-9171-2702 1 Rezac Ladislav 2 Formánek Tomáš https://orcid.org/0000-0003-4766-638X 1 Cavalié Thibault https://orcid.org/0000-0002-0649-1192 3 Jarchow Christopher 2 Lellouch Emmanuel 1 Hartogh Paul https://orcid.org/0000-0002-9550-6551 2 Murk Axel https://orcid.org/0000-0003-2949-844X 4 Kotiranta Mikko 4 Carrasco Gallardo Alberto https://orcid.org/0000-0002-6589-1946 2 Goodyear Samuel 2 Schulz-Ravanbakhsh Ali 2 Dabrowski Borys 2 Herpin Fabrice https://orcid.org/0000-0003-2977-5072 3 Kasai Yasuko 5 6 Murtagh Donal https://orcid.org/0000-0003-1539-3559 7 Olberg Michael 7 Rengel Miriam 2 Sagawa Hideo https://orcid.org/0000-0003-2064-2863 8 Szutowicz Slawomira 9 Wirström Eva 7 LIRA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université Paris Cité, 5 place Jules Janssen, 92195 Meudon, France Max-Planck-Institute for Solar System Research, Göttingen, Germany Univ. Bordeaux, CNRS, LAB, UMR 5804, F-33600 Pessac, France Institute of Applied Physics, University of Bern, Switzerland National Institute of Information and Communications Technology, Tokyo, Japan Institute of Science Tokyo, Tokyo, Japan Department of Physics and Astronomy, Chalmers University of Technology, Sweden Faculty of Science, Kyoto Sangyo University, Kyoto 603-8555, Japan Centrum Badań Kosmicznych Polskiej Akademii Nauk, Bartycka 18A, Warsaw, Poland 22 04 2026 2026 1 20 Copyright: © 2026 Raphael Moreno et al. 2026 This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/4.0/ This article is available from https://egusphere.copernicus.org/preprints/2026/egusphere-2026-2064/ The full text article is available as a PDF file from https://egusphere.copernicus.org/preprints/2026/egusphere-2026-2064/egusphere-2026-2064.pdf

The Submillimetre Wave Instrument (SWI) onboard the Jupiter Icy Moons Explorer (Juice) spacecraft consists of a 29 cm off-axis paraboloid antenna and two double-sideband heterodyne receivers operating in the frequency ranges of 530&ndash;638 and 1066&ndash;1286 GHz. This instrument is designed to study Jupiter&rsquo;s atmosphere and the exospheres of the Galilean moons.</p> <p>We used the Lunar-Earth-Gravity-Assist (LEGA) data from August 2024 to characterise this antenna using several SWI observations pointing towards the Earth. The data analysis of the LEGA observations dedicated to the antenna beam allows us to characterise the antenna beam Full Width at Half Maximum (FWHM), sidelobes, absolute pointing and receiver coalignement. Moreover, an estimate of the calibration efficiency factor has been obtained.