GRB 070420: optical rebrightening observed at mt. John. Jelinek, M. ; Tristram, P. ; de Ugarte Postigo, A. ; Gorosabel, J. ; Hale, F. ; Gilmore, A. ; Kilmartin, P. ; Castro-Tirado, A. J. Abstract Publication: GRB Coordinates Network Pub Date: 2007 Bibcode: 2007GCN..6338....1J