GRB 190515B: Optical observations from OSN. de Ugarte Postigo, A. ; Blazek, M. ; Izzo, L. ; Thoene, C. C. ; Kann, D. A. ; Bensch, K. ; Sota, A. Abstract Publication: GRB Coordinates Network Pub Date: 2019 Bibcode: 2019GCN.24558....1D