09 21 9 v 1 1 4 Se p 19 99 Prompt Optical Emission from Gamma-ray Bursts By

University of Michigan, Ann Arbor, MI 48109, USA Los Alamos National Laboratory, Los Alamos, NM 87545, USA NASA/Goddard Space Flight Center, Greenbelt, MD 20771, USA Universities Space Research Association, Seabrook, MD 20706, USA Raytheon Systems, Lanham, MD 20706, USA Università degli Studi di Ferrara, Ferrara, Italy Space Research Organization, Utrecht, The Netherlands Space Sciences Laboratory, University of California, Berkeley, CA 94720-7450, USA Lawrence Livermore National Laboratory, Livermore, CA 94550, USA Instituto Astrofisica Spaziale, Rome, Italy