GRB 991216 optical observations. Jensen, B. L. ; Pedersen, H. ; Hjorth, J. ; Pritchard, J. ; Abbott, T. ; Castro-Tirado, A. J. ; Pian, E. ; Vreeswijk, P. ; Greiner, J. Abstract Publication: GRB Coordinates Network Pub Date: December 1999 Bibcode: 1999GCN...498....1J