First on-sky results of a Fabry–Perot Instrument for Oxygen Searches (FIOS) prototype S. Rukdee, S. Ben-Ami, M. López-Morales, A. Szentgyorgyi, D. Charbonneau, J. García-Mejía and J. Buchner A&A, 678 (2023) A114 Published online: 13 October 2023 DOI: 10.1051/0004-6361/202346619