//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8876 SUBJECT: GRB 090131: Fermi GBM detection DATE: 09/02/03 03:23:47 GMT FROM: Adam Goldstein at Fermi-GBM/UAH A. Goldstein (UAH) and A.J. van der Horst (NASA/MSFC/ORAU) report on behalf of the Fermi GBM Team: "At 02:09:21.15 UT on 31 January 2009, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 090131 (trigger 255060563 / 090131090). The on-ground calculated location, using the GBM trigger data, is RA = 353.0, DEC = +16.4 (J2000 degrees, equivalent to 23h 32m, 16d 26'), with a statistical uncertainty of less than 1 degree (radius, 1-sigma containment) and an additional systematic error which is currently estimated to be 2 to 3 degrees. The angle from the Fermi LAT boresight is 40 degrees. The GBM light curve consists of two emission pulses, each with substructure and separated by a period of no significant emission above background. The total duration (T90) is about 36.4 s (8-1000 keV). The time-averaged spectrum from T0+0.0 s to T0+42.2 s is best fit by a Band function with Epeak = 58.4 +/- 3.9 keV, alpha = -1.27 +/- 0.07, and beta = -2.26 +/- 0.05 (chi-square 597.4 for 453 d.o.f.). The event fluence (8-1000 keV) in this time interval is (2.23 +/- 0.17)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0+6.4 s in the 8-1000 keV band is 47.9 +/- 10.0 ph/s/cm^2. The spectral and temporal analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8882 SUBJECT: GRB 090131: Suzaku WAM observation of the prompt emission DATE: 09/02/05 01:05:13 GMT FROM: Yoshitaka Hanabata at Hiroshima U Y. Hanabata, Y. Fukazawa, T. Takahashi, T. Uehara, C. Kira (Hiroshima U.), Y. Terada, M. Tashiro, Y. Urata, A. Endo, K. Onda, N. Kodaka, K. Morigami, T. Sugasahara, W. Iwakiri (Saitama U.), M. Ohno, M. Kokubun, M. Suzuki, T. Takahashi (ISAS/JAXA), K. Yamaoka, S. Sugita (Aoyama Gakuin U.), T. Enoto, K. Nakazawa, K. Makishima (Univ. of Tokyo), Y.E. Nakagawa, T. Tamagawa (RIKEN), E. Sonoda, M. Yamauchi, H. Tanaka, R. Hara, N. Ohmori, K. Kono, H. Hayashi (Univ. of Miyazaki), S. Hong (Nihon U.), N. Vasquez (Tokyo Tech), on behalf of the Suzaku WAM team, report: The long GRB 090131 (Goldstein et al., GCN 8876) triggered the Suzaku Wide-band All-sky Monitor (WAM) which covers an energy range of 50 keV - 5 MeV at 2009-01-31 02:09:24.187 UT (=T0). The observed light curve shows a multi-peaked structure starting at T0-5s, ending at T0+46s with a duration (T90) of about 32.6 seconds. The fluence in 100 - 1000 keV was 9.95(-0.59, +0.57) x 10^-6 erg/cm^2. The 1-s peak flux measured from T0+19s was 5.01(-0.39, +0.35) photons/cm^2/s in the same energy range. Preliminary result shows that the time-averaged spectrum from T0-5s to T0+46s is fitted by a single power-law with a photon index of 2.29(-0.15, +0.17) (chi^2/d.o.f = 11.4/13). All the quoted errors are at statistical 90% confidence level, in which the systematic uncertainties are not included. The light curves for this burst are available at: http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/trig/grb_table.html