GRB 150616A: Watcher optical upper limit. Murphy, D. ; Martin-Carrillo, A. ; Topinka, M. ; Hanlon, L. ; van Heerden, H. J. ; van Soelen, B. ; Meintjes, P. J. Abstract Publication: GRB Coordinates Network Pub Date: 2015 Bibcode: 2015GCN.17947....1M