GRB 150821A: Swift detection of a burst with an optical afterglow. Troja, E. ; Bernardini, M. G. ; Cenko, S. B. ; D'Avanzo, P. ; D'Elia, V. ; Evans, P. A. ; Melandri, A. ; Page, K. L. Abstract Publication: GRB Coordinates Network Pub Date: 2015 Bibcode: 2015GCN.18186....1T