TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4172 SUBJECT: GRB 051028 (=H3951): A GRB localized by HETE DATE: 05/10/28 19:28:06 GMT FROM: Roland Vanderspek at MIT GRB 051028 (=H3951): A GRB localized by HETE K. Hurley, G. Ricker, J-L. Atteia, N. Kawai, D. Lamb, and S. Woosley, on behalf of the HETE Science Team; M. Arimoto, T. Donaghy, E. Fenimore, M. Galassi, C. Graziani, N. Ishikawa, A. Kobayashi, J. Kotoku, M. Maetou, M. Matsuoka, Y. Nakagawa, T. Sakamoto, R. Sato, T. Shimokawabe, Y. Shirasaki, S. Sugita, M. Suzuki, T. Tamagawa, K. Tanaka, and A. Yoshida, on behalf of the HETE WXM Team; N. Butler, G. Crew, J. Doty, G. Prigozhin, R. Vanderspek, J. Villasenor, J. G. Jernigan, A. Levine, G. Azzibrouck, J. Braga, R. Manchanda, and G. Pizzichini, on behalf of the HETE Operations and HETE Optical-SXC Teams; M. Boer, J-F Olive, and J-P Dezalay, on behalf of the HETE FREGATE Team; report: At 13:36:01.47 UTC (48961.47 s UT) on 28 Oct 2005, the HETE FREGATE and WXM instruments detected event H3951, a bright GRB. The burst triggered FREGATE in the 30-400 keV energy band. The burst duration (T90) was 16 seconds in both the 30-400 keV band and the 7-30 keV band. Ground analysis of the WXM data produces a 90% confidence error region measuring 33 x 18 arcminutes with corners at the following coordinates: RA = 01h 50m 19.6s, Dec = +47d 41m 06s RA = 01h 47m 01.1s, Dec = +47d 38m 02s RA = 01h 46m 58.3s, Dec = +47d 55m 55s RA = 01h 50m 17.5s, Dec = +47d 58m 58s The 30-400 keV fluence of GRB 051028 is 6e-6 erg/cm2; the 2-30 keV fluences is 6e-7 erg/cm2. The hardness ratio allows us to classify this burst as a classical GRB. Further information will be available at http://space.mit.edu/HETE/Bursts/GRB051028