//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9294 SUBJECT: GRB 090428: Fermi GBM detection DATE: 09/04/29 15:20:35 GMT FROM: Elisabetta Bissaldi at MPE Elisabetta Bissaldi (MPE) reports on behalf of the Fermi GBM Team: "At 10:34:38.46 UT on 28 April 2009, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 090428 (trigger 262607680 / 090428441). The on-ground calculated location, using the GBM trigger data, is RA = 212.4, DEC = +37.3 (J2000 degrees, equivalent to 14h 10m, 37d 18'), with an uncertainty of 3.5 degrees (radius, 1-sigma containment, statistical only; there is additionally a systematic error which is currently estimated to be 2 to 3 degrees). The angle from the Fermi LAT boresight is 96 degrees. The GBM light curve consists of two peaks with a duration (T90) of about 8 s (8-1000 keV). The time-averaged spectrum from T0-0.51 s to T0+2.04 s is adequately fit by a power law function with an exponential high energy cutoff. The power law index is -0.59 +/- 0.16 and the cutoff energy, parameterized as Epeak, is 97 +/- 7 keV (chi squared 471 for 485 d.o.f.). The event fluence (8-1000 keV) in this time interval is (9.9 +/- 1.4)E-07 erg/cm^2. The 128-msec peak photon flux measured starting from T0+1.4 s in the 8-1000 keV band is 12.3 +/- 1.9 ph/s/cm^2. A Band function fits the spectrum equally well (chi squared 468 for 484 d.o.f.) with Epeak = 85 +/- 10 keV, alpha= -0.40 +/- 0.25 and beta = -2.7 +/- 0.4. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9295 SUBJECT: GRB 090428B: Fermi GBM detection DATE: 09/04/29 15:22:36 GMT FROM: Elisabetta Bissaldi at MPE Elisabetta Bissaldi (MPE) reports on behalf of the Fermi GBM Team: "At 13:15:11.06 UT on 28 April 2009, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 090428B (trigger 262617313 / 090428552). The on-ground calculated location, using the GBM trigger data, is RA = 0.8, DEC = +6.5 (J2000 degrees, equivalent to 00h 03m, 06d 30'), with an uncertainty of 4.4 degrees (radius, 1-sigma containment, statistical only; there is additionally a systematic error which is currently estimated to be 2 to 3 degrees). The angle from the Fermi LAT boresight is 101 degrees. The GBM light curve consists of a broad single peak with a duration (T90) of about 30 s (8-1000 keV). The time-averaged spectrum from T0-9.2 s to T0+15.3 s is adequately fit by a power law function with an exponential high energy cutoff. The power law index is -1.86 +/- 0.07 and the cutoff energy, parameterized as Epeak, is 65 +/- 16 keV (chi squared 279 for 241 d.o.f.). The event fluence (8-1000 keV) in this time interval is (5.2 +/- 0.3)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+3.1 s in the 8-1000 keV band is 10.1 +/- 0.7 ph/s/cm^2. A Band function fits the spectrum equally well (chi squared 278 for 240 d.o.f.) with Epeak = 53 +/- 19 keV, alpha = -1.81 +/- 0.13 and beta = -2.17 +/- 0.21. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9314 SUBJECT: GRB 090428B: Suzaku WAM observation of the prompt emission DATE: 09/05/01 05:22:26 GMT FROM: Takeshi Uehara at Hiroshima U T. Uehara, Y. Hanabata, T. Takahashi, Y. Fukazawa(Hiroshima U.), M. Ohno, M. Suzuki, M. Kokubun, T. Takahashi (ISAS/JAXA), K. Kono, E. Sonoda, M. Yamauchi, N. Ohmori, H. Hayashi, K. Noda, A. Daikyuji, Y. Nishioka (Univ. of Miyazaki), W. Iwakiri, M. Tashiro, Y. Terada, A. Endo, K. Onda, T. Sugasahara (Saitama U.), Y. Urata (NCU), T. Enoto, K. Nakazawa, K. Makishima (Univ. of Tokyo), K. Yamaoka, S. Sugita (Aoyama Gakuin U.), Y. E. Nakagawa, T. Tamagawa (RIKEN), S. Hong (Nihon U.), N. Vasquez (Tokyo Tech.), on behalf of the Suzaku WAM team, report: The long GRB 090428B (Fermi/GBM trigger 262617313 / 090428552, Bissaldi et al., GCN 9295) triggered the Suzaku Wide-band All-sky Monitor (WAM) which covers an energy range of 50 keV - 5 MeV at 13:15:12.66 UT (=T0). The observed light curve shows a single FRED-like peak starting at T0-10s, ending at T0+9s, with a duration (T90) of about 19.0 seconds. The fluence in 100 - 1000 keV was 2.6(+0.5/-0.9) X10^-6 erg/cm^2. The 1-s peak flux measured from T0+1s was 1.1 photons/cm^2/s in the same energy range. Preliminary result shows that the time-averaged spectrum from T0-10s to T0+9s is well fitted by a single power-law with a photon index of 2.0 (+0.5/-0.4) (chi^2/d.o.f = 5/7). 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