TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4550 SUBJECT: GRB 060121: A bright short/hard GRB localized by HETE-2 WXM DATE: 06/01/21 23:53:39 GMT FROM: Don Lamb at U.Chicago GRB 060121: A bright short/hard GRB localized by HETE-2 WXM M. Arimoto, G. Ricker, J-L. Atteia, N. Kawai, D. Lamb, and S. Woosley, on behalf of the HETE Science Team; 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, G. Pizzichini, and S. Gunasekera, on behalf of the HETE Operations and HETE Optical-SXC Teams; M. Boer, J-F Olive, J-P Dezalay, and K. Hurley, on behalf of the HETE FREGATE Team; report: At 22:24:54.5 UTC (80694.5 SOD) on 21 January 2006 the HETE FREGATE, WXM, and SXC instruments detected event H4010, a bright short/hard GRB. The WXM flight location was distributed in a GCN Notice at 22:25:08 UTC, 13 seconds after the start of the burst. Ground analysis of the WXM data yields a best-fit location R.A. = +09h 10m 04s ; Dec. = +45d 41' 24" (J2000), with a 90% confidence error radius of 8 arcminutes. The T90 duration of the burst is approximately 2 s in the FREGATE 80-400 keV energy band. Further analyses are in progress. Further information about this burst will be available at the following URL: http://space.mit.edu/HETE/Bursts/GRB060121