Real-time and pre-burst optical data for GRBs R. Hudec, Z. Ceplecha, P. Spurný, J. Florián, A. Kolář, J. Boček, J. Borovička and P. Kroll Astron. Astrophys. Suppl. Ser., 138 3 (1999) 591-592 Published online: 15 September 1999 DOI: 10.1051/aas:1999364