LST-1 observations of an enormous flare of BL Lacertae in 2021 - Nozaki, S.; Asano, K.; Escudero, J.; Emery, G.; Priyadarshi, C.; Abe, K.; Abe, S.; Aguasca-Cabot, A.; Agudo, I.; Alvarez Crespo, N.; Antonelli, L.A.; Aramo, C.; et al. (Proceedings of Science, 2024)