GRB 100503A

Y. Hanabata, T. Uehara, T. Takahashi, Y. Fukazawa (Hiroshima U.)
K. Yamaoka (Aoyama Gakuin U.), S. Sugita (Nagoya U.),
Y. Terada, M. Tashiro, W. Iwakiri, K. Takahara, T. Yasuda (Saitama U.),
M. Ohno, M. Suzuki, M. Kokubun, T. Takahashi (ISAS/JAXA),
Y. E. Nakagawa, T. Tamagawa (RIKEN), N. Ohmori, A. Daikyuji, Y. Nishioka,
M. Yamauchi (Univ. of Miyazaki), N. Vasquez (Tokyo Tech.), Y. Urata,
H. M. Lin (NCU), T. Enoto, K. Nakazawa, K. Makishima (Univ. of Tokyo),
S. Hong (Nihon U.), on behalf of the Suzaku WAM team, report:

The long GRB 100503A (Fermi/GBM trigger #294585485; Tierney et al.,
GCN 10714
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 ) triggered the Suzaku Wide-band All-sky Monitor (WAM) which
covers an energy of 50 keV - 5 MeV at 2010-05-03 13:18:51.17 UT (T=0).

The observed light curve shows a multi-peaked structure lasting from
T0-51s to T0+89s with T90 of about 103 seconds. The fluence in 100 -
1000 keV was 8.56 (-2.58, +2.10)x10^-6 erg/cm^2. The 1-s peak flux
measured from T0-1s was 1.23 (-0.27, +0.24) photons/cm^2/s in the
same energy range.

Preliminary result shows that the time-averaged spectrum from T0-51s
to T0+89s is well fitted by a single power-law with a photon index
of 2.04 (-0.29, +0.36) (chi^2/d.o.f = 11.1/11).

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

The light curves for this burst wiil be available at:
http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/trig/grb_table.html

Dave Tierney (UCD) and Sheila McBreen (UCD/MPE) 
report on behalf of the Fermi GBM Team: 

"At 13:18:03.89 UT on 03 May 2010, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 100503A (trigger 294585485 / 100503554).

The on-ground calculated location, using the GBM trigger 
data, is RA = 147.5, DEC = 4.0 (J2000 degrees, 
equivalent to 09 h 50 m, 4 d 0 '), with an uncertainty 
of 1.5 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 63 degrees.

The GBM light curve consists of multiple peaks
with a duration (T90) of 129.5 +/- 9.9 s (50-300 keV). 
The time-averaged spectrum from T0-4 s to T0+52 s is 
best fit by a power law function with an exponential
high energy cutoff. The power law index is -0.99 (+0.06/-0.05)
and the cutoff energy, parameterized as Epeak, 
is 211.60 (+18.30/-15.50) keV (Cstat 877 for 601 d.o.f.).

The event fluence (10-1000 keV) in this time interval is 
(1.23 +/- 0.03)E-5 erg/cm^2. The 1-sec peak photon flux measured 
starting from T0+46.5 s in the 10-1000 keV band 
is 5.8 +/- 0.2 ph/s/cm^2.

A Band function fits the spectrum equally well 
(Cstat 871 for 600 d.o.f.) with Epeak= 162.60 (+21.60/-17.00) keV, 
alpha = -0.85 (+0.09/-0.09) and beta = -2.24 (+0.13/-0.21). 


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