GRB 090530B

A.J. van der Horst (NASA/MSFC/ORAU) reports on behalf of the
Fermi GBM Team:

"At 18:14:24.42 UT on 30 May 2009, the Fermi Gamma-ray Burst Monitor
(GBM) triggered and located GRB 090530B (trigger 265400066 / 090530.760).
The on-ground calculated location, using the Fermi GBM trigger data,
is RA = 73.2, Dec = +13.8 (J2000 degrees, equivalent to
J2000 4h53m, +13d47'), with a statistical uncertainty of less than 1 degree
(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 84 degrees.

The GBM light curve of this long and soft GRB consists of a double peaked
FRED, with a total duration (T90) of 194 s (8-1000 keV). The time-averaged
spectrum from T0-3.1 to T0+110.6 s is best fit by a Band function with
alpha = -0.71 +/- 0.06, beta = -2.42 +/- 0.05, and Epeak = 67 +/- 3.
The fluence (8-1000 keV) in this interval is (5.9 +/- 0.4)E-5 erg/cm^2.
The 1-sec peak photon flux measured starting from T0+10.2s in the
8-1000 keV band is 10.8 +/- 2.0 ph/s/cm^2.

The spectral and temporal analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."

K. Noda, E. Sonoda, M. Yamauchi, N. Ohmori, H. Hayashi,
K. Kono, A. Daikyuji, Y. Nishioka (Univ. of Miyazaki),
Y. Hanabata, T. Uehara, T. Takahashi, Y. Fukazawa (Hiroshima U.),
M. Ohno, M. Suzuki, M. Kokubun, T. Takahashi (ISAS/JAXA),
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 090530B (Fermi/GBM trigger #265400066 / 090530.760;
van der Horst et al., GCN 9472
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was detected by the the Suzaku Wide-band All-sky Monitor (WAM) which
covers an energy range of 50 keV - 5 MeV at 18:14:23 UT (=T0).

The observed light curve shows a single peak
starting at T0-1s, ending at T0+219s,
with a duration (T90) of about 113 seconds.
The fluence in 100 - 1000 keV was 2.41 ( +0.06/ -0.07 )x10-5 erg/cm2.
The 1-s peak flux measured from T0+8s was 2.39 ( +0.08/ -1.41 )
photons/cm2/s
in the same energy range.

Preliminary result shows that the time-averaged spectrum from T0-1s to
T0+219s is well fitted by a single power-law with a photon index
of 3.30 ( +0.14/ -0.13 ) (chi2/d.o.f = 31/17 ).

All the quoted errors are at statistical 90% confidence level,
in which the systematic uncertainties are not included.

The light curves with 1-sec time resolution for this burst will be
appeared at:

http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/untrig/grb_table.html