A fast-filament eruption observed in the Hα spectral line - I. Imaging spectroscopy diagnostic Denis P. Cabezas, Kiyoshi Ichimoto, Ayumi Asai, Satoru UeNo, Satoshi Morita, Ken-ichi Otsuji and Kazunari Shibata A&A, 690 (2024) A172 Published online: 07 October 2024 DOI: 10.1051/0004-6361/202450099