TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3785 SUBJECT: GRB050807(=H3889): An X-Ray Rich GRB Localized by HETE DATE: 05/08/12 21:49:31 GMT FROM: Joel Villasenor at MIT M. Maetou, 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, J. Kotoku, M. Matsuoka, Y. Nakagawa, T. Sakamoto, R. Sato, Y. Shirasaki, M. Suzuki, T. Tamagawa, K. Tanaka, Y. Yamamoto, 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, J-P Dezalay, and K. Hurley, on behalf of the HETE FREGATE Team; report: The HETE FREGATE, WXM, and SXC instruments detected GRB 050807 (=H3889) at 10:58:45 UT (39525 SOD) on 7 August 2005. The correct WXM flight localization was first reported in a GCN Notice issued at 10:59:19 UT, which was 34s after the burst trigger. Further WXM and SXC ground localizations were reported in a GCN Notice issued at 13:47:18 UT. The final WXM ground localization can be expressed as an 8 by 48 arcminute box (90% confidence) that is centered at WXM-Ground: RA = 20h 13m 27s, DEC = -36d 57' 06" (J2000) and defined by the corners: RA = 20h 13m 16s, DEC = -37d 21' 43" RA = 20h 12m 40s, DEC = -37d 18' 54" RA = 20h 13m 38s, DEC = -36d 32' 31" RA = 20h 14m 14s, DEC = -36d 35' 20". The SXC localization could only be localized along one axis, and hence yields a 3 by 32 arcminute box that is centered at SXC-Ground: RA = 20h 13m 27s, DEC = -36d 56' 12" (J2000) and defined by the corners: RA = 20h 13m 39s, DEC = -36d 40' 23" RA = 20h 13m 00s, DEC = -37d 11' 20" RA = 20h 13m 14s, DEC = -37d 12' 18" RA = 20h 13m 54s, DEC = -36d 40' 52". The burst has a duration T_90 of ~55 seconds in 6-40 keV and 6-80 keV, and a T_90 of ~28 seconds in 30-400 keV. Preliminary spectral analyses show the 2-30 keV fluence of GRB 050807 to be 1.3 x 10-6 ergs cm-2 and the 30-400 keV fluence to be 2.2 x 10-6 ergs cm-2. Thus, GRB 050807 is classified as an "X-ray-rich" GRB. A light curve, skymap, and spectral information for GRB 050807 are provided at the following URL: http://space.mit.edu/HETE/Bursts/GRB050807 This message may be cited.