HETE Observations of the Gamma-Ray Burst GRB030329: Evidence for an Underlying Soft X-ray Component

An exceptionally intense gamma-ray burst, GRB030329, was detected and localized by the instruments on board the High Energy Transient Explorer satellite (HETE) at 11:37:14 UT on 29 March 2003. The burst consisted of two ∼10s pulses of roughly equal brightness and an X-ray tail lasting >100s. The energy Center for Space Research, Massachusetts Institute of Technology, 70 Vassar Street, Cambridge, MA, 02139. Department of Astronomy and Astrophysics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637. Laboratoire d’Astrophysique, Observatoire Midi-Pyrénées, 14 Ave. E. Belin, 31400 Toulouse, France. Department of Physics, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8551, Japan. RIKEN (Institute of Physical and Chemical Research), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan. University of California at Berkeley, Space Sciences Laboratory, Berkeley, CA, 94720-7450. National Astronomical Observatory, Osawa 2-21-1, Mitaka, Tokyo 181-8588 Japan. Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM, 87545. Department of Physics, Aoyama Gakuin University, Chitosedai 6-16-1 Setagaya-ku, Tokyo 157-8572, Japan. Tsukuba Space Center, National Space Development Agency of Japan, Tsukuba, Ibaraki, 305-8505, Japan. Centre d’Etude Spatiale des Rayonnements, Observatoire Midi-Pyrénées, 9 Ave. de Colonel Roche, 31028 Toulouse Cedex 4, France. Department of Astronomy and Astrophysics, University of California at Santa Cruz, 477 Clark Kerr Hall, Santa Cruz, CA 95064. NASA Goddard Space Flight Center, Greenbelt, MD, 20771. Instituto Nacional de Pesquisas Espaciais, Avenida Dos Astronautas 1758, São José dos Campos 12227010, Brazil. Department of Astronomy and Astrophysics, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai, 400 005, India. Consiglio Nazionale delle Ricerche, IASF, Sezione di Bologna, via Piero Gobetti 101, 40129 Bologna, Italy. Faculty of engineering, Miyazaki University, Gakuen Kibanadai Nishi, Miyazaki 889-2192, Japan. Department of Earth and Space Science, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan.