An extremely energetic supernova from a very massive star in a dense medium

M. Nicholl, P. K. Blanchard, E. Berger, R. Chornock, R. Margutti, Sebastián Gómez, R. Lunnan, Adam A. Miller, Wen‐fai Fong, G. Terreran, Alejandro Vigna-Gómez, Kornpob Bhirombhakdi, Allyson Bieryla, P. Challis, Russ R. Laher, Frank J. Masci, K. Paterson