Author affiliations
1 Astronomical Institute "Anton Pannekoek," University of Amsterdam, and Center for High Energy Astrophysics, Kruislaan 403, 1098 SJ Amsterdam, The Netherlands
2 Institute of Astronomy, Madingley Road, Cambridge CB3 0HA, England, UK
3 CNR Bologna, Via P. Gobetti 101, 40129 Bologna, Italy
4 Physics Department, University of Alabama in Huntsville, Huntsville, AL 35899
5 Universities Space Research Association
6 NASA/MSFC, Code ES-84, Huntsville, AL 35812
7 Space Research Organization of the Netherlands (SRON), Sorbonnelaan 2, Utrecht, The Netherlands
8 ESO, Casilla 19001, Santiago 19, Chile
9 Anglo-Australian Observatory, P.O. Box 296 Epping, NSW 2121, Australia
10 Cerro Tololo Inter-American Observatory, Casilla 603, La Serena, Chile
11 UC Berkeley, Space Sciences Laboratory, Berkeley, CA 94720-7450
12 Department of Astronomy, University of Toronto, 60 St. George Street, Toronto, Ontario M5S 3H8, Canada
13 Instituto Astrofísica de Canarias, Tenerife, Spain
14 Istituto di Astrofisica Spaziale, CNR, Via Fosso del Cavaliere, Roma, I-00133, Italy
15 University of Wales, Cardiff, Wales, UK
16 University of Bristol, Bristol, England, UK
17 Department of Astronomy, University of Maryland, College Park, MD 20742
18 Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138
19 Laboratorio de Astrofísica Espacial y Física Fundamental (LAEFF-INTA), P.O. Box 50727, E-28080 Madrid, Spain
20 Instituto de Astrofísica de Andalucía (IAA-CSIC), P.O. Box 03004, E-18080 Granada, Spain
21 Astrophysikalisches Institut Potsdam, D-14482 Potsdam, Germany
22 Universitäts-Sternwarte Göttingen, Geismarlandstr. 11, D-37083 Göttingen, Germany
=25.5±0.5. Its optical colors 2.1 days after the burst imply a spectral slope of -0.66±0.70. The γ-ray spectrum as observed with BATSE shows that it is among the 4% softest bursts ever recorded. We argue that the rapid optical decay may be a reason for the nondetection of some low-energy afterglows of GRBs.