GRB 100322A

A.J. van der Horst (NASA/MSFC/ORAU) and D. Tierney (UCD)
report on behalf of the Fermi GBM Team:

"At 01:05:09.64 UT on 22 March 2010, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 100322A (trigger 290912711 / 100322045).
The on-ground calculated location, using the GBM trigger data, is
RA=23.33, Dec=-10.22 (J2000 degrees, equivalent to 23h20m, -10d13'),
with an uncertainty of 1.20 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 multiple peaks with a duration
(T90) of 37.0 +/- 0.3 s (50-300 keV).
The time-averaged spectrum from T0-1.0 s to T0+41.0 s is best fit by
a Band function with Epeak = 309 +/- 16 keV, alpha = -0.88 +/- 0.02,
and beta = -2.15 +/- 0.05 (Cstat 1095 for 602 d.o.f.).

The event fluence (10-1000 keV) in this time interval is
(6.13 +/- 0.04)E-5 erg/cm^2. The 1-sec peak photon flux
measured starting from T0+1.1 s in the 10-1000 keV band
is 16.1 +/- 0.3 ph/s/cm^2.

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

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

The bright long GRB 100322A  (Fermi/GBM trigger #290912711
; van der Host et al., GCN 10539
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 )
triggered the Suzaku Wide-band All-sky Monitor (WAM)
which covers an  energy range of 50 keV - 5 MeV
at 2010-03-22 01:05:09.65 UT (=T0).

The observed light curve shows a multi-peaked structure
lasting from T0 to T0+50s and a weak post cursor
seen at T0+70s with T90 of about 37 seconds.
The fluence in 100 - 1000 keV was 5.00 (-0.17, +0.09)x10^-5 erg/cm^2.
The 1-s peak flux measured from T0+33s was
8.04 (-0.39, +0.26) photons/cm^2/s in the same energy range.

Preliminary result shows that the time-averaged spectrum from
T0 to T0+42s is well fitted by a power-law with exponential cutoff model:
dN/dE ~  E^{-alpha} * exp(-(2-alpha)*E/Epeak) with
alpha       1.42 (-0.15, +0.13), and
Epeak       601 (-57, +70) keV (chi^2/d.o.f. = 26.2/24).

Due to the brightness of this burst, a 2% systematic error
was added for each energy channel.
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

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 intense GRB 100322A (Fermi/GBM trigger #290912711,
van der Host et al., GCN 10539
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 ) triggered Konus-Wind
at T0=03905.772s UT (01:05:05.772)

The burst light curve shows a complex structure containing
two main pulses with a total duration of ~50 s.
Additionally, a much weaker pulse was observed around T0+75s.

The first of the two main pulses has a distinctly softer spectrum
than the second one. No evident spectral evolution was detected
within the pulses.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB100322_T03905/

As observed by Konus-Wind the burst
had a fluence of 7.3(+/-0.5)x10-5 erg/cm2,
and a 256-ms peak flux measured from T0+31.744s
of 6.5(+/-0.4)x10-6 erg/cm2/s
(both in the 20 keV - 5 MeV energy range).

The spectrum of the first, softer pulse
(measured from T0 to T0+16.384 s) is well fitted
in the 20 keV - 5 MeV range by a power law
with exponential cutoff model, for which
alpha = -0.86(+/-0.15),
and Ep = 150(-10, +12) keV (chi2 = 72/74 dof).

The spectrum of the second, harder part of the burst
(from T0+16.384 to T0+45.568 s) is also well fitted
in the 20 keV - 5 MeV range by a power law
with exponential cutoff model, for which
alpha = -0.99(+/-0.06),
and Ep = 610(-62, +75) keV (chi2 = 77/74 dof).

The spectrum at the maximum count rate
(measured from T0+31.744 to T0+37.376 s) is well fitted
in the 20 keV - 5 MeV range by a power law
with exponential cutoff model, for which
alpha = -0.92(+/-0.07),
and Ep = 707(-70, +82) keV (chi2 = 72/74 dof).

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