TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2442 SUBJECT: XRF031109 (=H2919): A very long XRF localized by HETE DATE: 03/11/11 02:57:33 GMT FROM: Roland Vanderspek at MIT XRF031109 (=H2919): A very long XRF localized by HETE T. Tamagawa, G. Ricker, J-L. Atteia, N. Kawai, D. Lamb, and S. Woosley on behalf of the HETE Science Team; T. Donaghy, C. Graziani, E. Fenimore, M. Galassi, M. Matsuoka, T. Sakamoto, Y. Shirasaki, M. Suzuki, K. Torii, A. Yoshida, Y. Nakagawa, R. Satoh, Y. Urata, T. Yamazaki and Y. Yamamoto, on behalf of the HETE WXM Team; A. Dullighan, R. Vanderspek, G. Crew, J. Doty, G. Prigozhin, J. Villasenor, J. G. Jernigan, N. Butler, 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, C. Barraud, and K. Hurley on behalf of the HETE FREGATE Team; report: At 19:28:59 UTC (70138 s UT) on 9 November 2003, the HETE FREGATE and WXM instruments detected event H2919, a very long X-ray Flash (XRF). The burst triggered the WXM in the 2-25 keV energy band. No prompt notification was distributed due to the low image S/N of the burst in the flight analysis. Initial ground analyses showed the burst to be soft, with a duration of ~20s. Because this burst was detected seven minutes before the star cameras had come on line, although the WXM data localized the burst to a 15' radius, the original error estimate for the celestial coordinates was four degrees. Further analysis of the burst data set has revealed that the burst continued at a low level for at least seven and perhaps 10 minutes: we estimate t50 to be 310 seconds, t90 to be 480s. Localization of the photons detected near the end of the burst, and therefore just before the beginning of star tracker operations, allows the burst to be localized to an error circle of 20' radius centered at R.A. = 00h 17m 03s.49, (J2000) Dec. = -7o 08' 41" An automated fit of a cutoff power-law spectrum has been performed for H2919. The fit of the model to the data is posted at http://space.mit.edu/HETE/Bursts/GRB031109 The automated fit for the first 52 seconds of the burst gives the following values of Epeak and the burst fluence (25-100 keV): -- Epeak = 29 keV -- Fluence = 1.1e-06 erg/cm^2 NB: The S/N of the fit decreases significantly for longer integration times. Also posted at the above website are the following data, in the formats described by Vanderspek (GCN 2421): -- Fregate light curve and ascii data tables (energy bands A [7-30 keV], B [7-80 keV], and C [30-400 keV]) -- Color-color plot location of H2919 relative to other HETE-localized bursts -- Signal-to-noise histogram location of H2919 in Fregate Band C relative to other HETE-localized bursts This message may be cited.