GRB 071021: z-band detection. Malesani, D. ; Piranomonte, S. ; Tagliaferri, G. ; Chincarini, G. ; Covino, S. ; Fiore, F. ; Stella, L. Abstract Publication: GRB Coordinates Network Pub Date: 2007 Bibcode: 2007GCN..6972....1M