TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2662 SUBJECT: GRB040825B (=H3510): An XRF Localized in Real Time by HETE DATE: 04/08/26 03:25:35 GMT FROM: Roland Vanderspek at MIT GRB040825B (=H3510): An XRF Localized in Real Time by HETE Y. Urata, 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, M. Matsuoka, Y. Nakagawa, T. Sakamoto, R. Sato, Y. Shirasaki, M. Suzuki, T. Tamagawa, T. Yamazaki, Y. Yamamoto, and A. Yoshida, on behalf of the HETE WXM Team; N. Butler, G. Crew, J. Doty, A. Dullighan, 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; C. Barraud, M. Boer, J-F Olive, J-P Dezalay, and K. Hurley, on behalf of the HETE FREGATE Team; report: At 16:21:37 UTC (58897 s UT) on 25 August 2004, the HETE FREGATE and WXM instruments detected event GRB040825B (=H3510), a long XRF. The burst triggered the WXM in the 2-30 keV energy band; the burst duration is roughly 80 seconds. A flight localization was automatically forwarded to the GCN 31 seconds after the trigger. The flight localization was a circle of 14' radius centered at RA = 22h 47m 22s, Dec = -02d 19' 05" (J2000) Subsequent analysis of the full data set allowed the burst error region to be reduced to a 160 sq. arcmin error box with the following coordinates, distributed by GCN Notice 1.8 hours after the trigger: RA = 22h 46m 38.9s, Dec = -02d 33m 40 RA = 22h 46m 01.9s, Dec = -02d 29m 17s RA = 22h 46m 28.6s, Dec = -02d 15m 14s RA = 22h 47m 05.5s, Dec = -02d 19m 41s Preliminary spectral analyses show the burst spectrum is well fit by a cutoff powerlaw model with an Epeak of 23 keV. The burst fluence is 1.3e-6 erg/cm2 in the 2-30 keV band, 6.3e-7 erg/cm2 in the 30-400 keV band; GRB040825B is therefore an XRF. Details of this burst can be found on the HETE web page at http://space.mit.edu/HETE/Bursts/GRB040825B. Further observations of this source are encouraged. This message can be cited.