The Early Phases of Supernova 2020pni: Shock Ionization of the Nitrogen-enriched Circumstellar Material. - Terreran, G.; Jacobson-GalĂˇn, W. V.; Groh, J. H.; Margutti, R.; Coppejans, D. L.; Dimitriadis, G.; Kilpatrick, C. D.; Matthews, D. J.; Siebert, M. R.; Angus, C. R.; Brink, T. G.; Filippenko, A. V.; et al. (Astrophysical Journal, 2022)