GRB 100324B

K. Hurley, on behalf of the IPN team,

I. G. Mitrofanov, D. Golovin, M. L. Litvak, and A. B. Sanin,
on behalf of the HEND-Odyssey GRB team,

W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr, on
behalf of the GRS-Odyssey GRB team,

S. Golenetskii, R. Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, and
T. Cline, on behalf of the Konus-Wind team,

K. Yamaoka, M. Ohno, Y. Hanabata, Y. Fukazawa, T. Takahashi, M. Tashiro,
Y. Terada, T. Murakami, and K. Makishima, on behalf of the Suzaku WAM team,

V. Connaughton, M. Briggs, and C. Meegan, on behalf of the Fermi GBM team,
and

J. Goldsten, on behalf of the MESSENGER NS GRB team, report:

This bright, long GRB was detected by Fermi (GBM), Suzaku (WAM),
Konus-Wind, Mars Odyssey (HEND), and MESSENGER (GRNS) AT 04:07:36 UT on
March 24, 2010.  We have triangulated it to a preliminary, 38 square
arcminute (3 sigma) error box whose coordinates are:


         RA(2000)       Dec(2000)
Center   39.672         -19.287 

Corners  39.713         -19.311
         39.717         -19.449
         39.628         -19.123
         39.632         -19.262

This error box may be improved.  Details of this burst will be presented
in forthcoming GCN Circulars.

S. Golenetskii, R.Aptekar, D. Frederiks, E. Mazets, V. Pal'shin,
P. Oleynik, M. Ulanov, D. Svinkin, and T. Cline on behalf
of the Konus-Wind team, report:

The long bright GRB 100324B (localized by IPN;
Hurley et al., GCN 10554
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 ) triggered Konus-Wind
at T0=14852.507s UT (04:07:32.507)

The burst light curve shows a complex structure
with a total duration of ~15 s. A hard to soft
spectral evolution is apparent in the course of the burst.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB100324_T14852/

As observed by Konus-Wind the burst
had a fluence of 4.6(+/-0.2)x10-5 erg/cm2,
and a 256-ms peak flux measured from T0+4.864s
of 8.8(+/-0.6)x10-6 erg/cm2/s
(both in the 20 keV - 2 MeV energy range).

The time-integrated spectrum of the burst
(from T0 to T0+13.824 s) is well fitted
in the 20 keV - 2 MeV range by the GRB (Band)
model, for which:
the low-energy photon index alpha = -0.51 (-/+0.09),
the high energy photon index beta = -2.95(<-2.6),
the peak energy Ep = 397(-30, +41)keV (chi2 = 59/57 dof).

The spectrum at the maximum count rate
(measured from T0+3.840 to T0+5.632 s) can be fitted
in the 20 keV - 2 MeV range by the GRB (Band)
model, for which:
the low-energy photon index alpha = -0.42 (-/+0.16),
the high energy photon index beta = -2.6(-0.85,+0.25),
the peak energy Ep = 283(-30, +44)keV (chi2 = 71/57 dof).

All the quoted results are preliminary.
All the quoted errors are at the 90% confidence level.

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


The bright IPN localized GRB 100324B (GCN 10554
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  ; Hurley et al.)
triggered the Suzaku Wide-band  All-sky Monitor (WAM) which covers an 
 energy range of 50 keV - 5 MeV at 04:07:36.130 UT (=T0). 
The observed light curve shows a multi-peaked structure starting at T0s, ending 
 at T0+10s, with a duration (T90) of about 9.7 seconds. 
The fluence in 100 - 1000 keV was 3.20 (-0.07, 0.05) x10^-05 erg/cm^2. 
The 1-s peak flux measured from T0+2s was 15.7 +/- 0.3 photons/cm^2/s in the same 
 energy range.

Preliminary result shows that the time-averaged spectrum from 
T0s to T0+10s is well fitted by a GRB Band model as follows.
the low-energy photon index alpha: -0.91 (-0.14, 0.16),
the high-energy photon index beta: -3.05 (-0.53, 0.26),
and the peak energy Epeak: 472 (-25, 27) keV (chi^2/d.o.f = 61.2/50).

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