GRB 050817: optical observations. Tristram, P. ; de Ugarte Postigo, A. ; Gorosabel, J. ; Guzyi, S. ; Jelanek, M. ; Castro-Tirado, A. J. ; Yock, P. Abstract Publication: GRB Coordinates Network Pub Date: 2005 Bibcode: 2005GCN..3823....1T