A kilonova following a long-duration gamma-ray burst at 350 Mpc

The Fong group at Northwestern acknowledges support by the National Science Foundation under grant nos. AST-1814782 and AST-1909358 and CAREER grant no. AST-2047919. W.F. gratefully acknowledges support by the David and Lucile Packard Foundation. A.J.L. and D.B.M. are supported by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement no. 725246). M.N. and B.P.G. are supported by the ERC under the European Union’s Horizon 2020 research and innovation programme (grant agreement no. 948381). M.N. acknowledges a Turing Fellowship. G.P.L. is supported by the UK Science and Technology Facilities Council grant ST/S000453/1. A.R. and E.M. acknowledge support from the INAF research project ‘LBT - Supporto Arizona Italia’. J.F.A.F. acknowledges support from the Spanish Ministerio de Ciencia, Innovación y Universidades through the grant PRE2018-086507. D.A.K. and J.F.A.F. acknowledge support from Spanish National Research Project RTI2018-098104-J-I00 (GRBPhot). W. M. Keck Observatory and MMT Observatory access was supported by Northwestern University and the Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA). Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration (NASA). The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. We wish to recognize and acknowledge the very important cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. Observations reported here were obtained at the MMT Observatory, a joint facility of the University of Arizona and the Smithsonian Institution. On the basis

Astrophysics Research at the University of Leicester

Science and Technology Facilities Council