GRB 080925
GCN Circular 8291
Subject
GRB 080925: Fermi GBM Detection
Date
2008-09-27T05:56:47Z (17 years ago)
From
Alexander van der Horst at NASA/MSFC <avdhorst@science.uva.nl>
Adam Goldstein (UAH), Alexander van der Horst (NASA/ORAU) and Rob Preece
(UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team:
"At 18:35:55 UT on 25 September 2008, the Fermi Gamma-Ray Burst Monitor
(GBM) triggered and located the bright GRB 080925 (trigger 244060556 /
080925.775). The on-ground calculated location, using the GBM trigger
data, is RA = 96.1, Dec = +18.2 (J2000 degrees, equivalent to 6h 24m,
+18d 12'), with a statistical uncertainty 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
Large Area Telescope (LAT) boresight is 38 degrees.
This GRB has several peaks, with T90 (50-300 keV) = 29 s and
T50 (50-300 keV) = 9 s. The time-averaged spectrum (8 keV-1 MeV)
from T0 to T0+16.6 s is best fit by a Band function with
Epeak = 120 +/- 5 keV, alpha = -0.53 +/- 0.05, and beta = -2.26 +/- 0.08.
The fluence (50-300 keV) is 9.7E-6 erg/cm^2.
The spectral analysis results presented above are preliminary; the final
results will be published in the GBM GRB Catalog."
GCN Circular 8309
Subject
GRB 080925: Suzaku WAM observation of the prompt emission
Date
2008-10-03T01:10:38Z (17 years ago)
From
Kazutaka Yamaoka at Aoyama Gakuin U <yamaoka@phys.aoyama.ac.jp>
T. Enoto, K. Nakazawa, K. Makishima (Univ. of Tokyo), S. Sugita,
K. Yamaoka (Aoyama Gakuin U.), M. Ohno, M. Kokubun, M. Suzuki,
T. Takahashi (ISAS/JAXA), Y.E. Nakagawa, T. Tamagawa (RIKEN),
T. Uehara, T. Takahashi, Y. Fukazawa, C. Kira, Y. Hanabata (Hiroshima U.),
M. Tashiro, Y. Terada, Y. Urata, A. Endo, K. Onda,
N. Kodaka, K. Morigami, T. Sugasahara, W. Iwakiri (Saitama U.),
E. Sonoda, M. Yamauchi, H. Tanaka, R. Hara, N. Ohmori (Univ. of Miyazaki),
S. Hong (Nihon U.), on behalf of the Suzaku WAM team, report:
The long GRB080925 (Fermi-GBM triggered ; Goldstein et al., GCN
8291) triggered the the Suzaku Wide-band All-sky Monitor (WAM)
which covers an energy range of 50 keV - 5 MeV at 18:35:56.853
UT (=T0).
The observed light curve shows a multi-peaked structure (peaks at
T0+1s, T0+5s, and T0+14s) with a duration (T90) of about 15 seconds.
The fluence in 100 - 1000 keV was 7.3(+0.3, -0.2) X 10^-6 erg/cm^2.
The 1-s peak flux measured from T0+5s was 2.8 photons/cm^2/s
in the same energy range.
Preliminary result shows that the time-averaged spectrum from T0-10s
to T0+20s is well fitted by a single power-law with a photon index
of 2.33(+0.16/-0.18) (chi^2/d.o.f = 36.0/42) in the 150-1000 keV
energy band. 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 availabel at:
http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/trg/grb_table.html