GRB 130320B

K. Hurley on behalf of the Mars Odyssey and MESSENGER GRB teams,

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

J. Goldsten, on behalf of the MESSENGER GRNS GRB team,

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

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

S. Barthelmy, J. Cummings, N. Gehrels, H. Krimm, and D. Palmer, on
behalf of the Swift-BAT team,

A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo, and C.
Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team, and

G. Di Cocco, F. Fuschino, M. Galli, C. Labanti, and M. Marisaldi, on
behalf of the AGILE MCAL team, report:

The very long, bright GRB 130320B was observed by Konus-Wind, Mars 
Odyssey (HEND), INTEGRAL (SPI-ACS), Fermi (GBM trigger 385478797), Swift 
(BAT), AGILE (MCAL), and MESSENGER (GRNS) at about 48247 s UT 
(13:24:07). The burst was outside the coded field of view of the BAT.

The burst shows three emission episodes with a total duration of ~380 s.
The entire burst was observed  by Konus-Wind, INTEGRAL-SPI-ACS, and Mars 
Odyssey (HEND). AGILE (MCAL) observed only the first (main) episode. 
Fermi (GBM) triggered on the second episode while exiting the SAA and 
also observed the third episode. MESSENGER (GRNS) triggered twice: on 
the first and on the third episode. These two episodes were also 
observed by Swift (BAT).

We have triangulated it to a 3 sigma error box whose
coordinates are:
---------------------------------------------
   RA(2000), deg                 Dec(2000), deg
  ---------------------------------------------
  Center:
   195.539 (13h 02m 09s) -71.259 (-71d 15' 34")
  Corners:
   197.046 (13h 08m 11s) -71.078 (-71d 04' 39")
   196.172 (13h 04m 41s) -71.308 (-71d 18' 30")
   194.010 (12h 56m 02s) -71.427 (-71d 25' 38")
   194.909 (12h 59m 38s) -71.208 (-71d 12' 29")
  ---------------------------------------------
The error box area is 431 sq. arcmin, and its maximum dimension is
62 arcmin (the minimum one is 22 arcmin).

The IPN localizations of all three pulses are consistent with a common 
source.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB130320_T48251/IPN/

The time history and spectrum will be given in a forthcoming GCN
Circular.

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 very long intense GRB 130320B
(IPN triangulation: Hurley et al., GCN 14354
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triggered Konus-Wind at T0=48251.726s UT (13:24:11.726)

The burst consists of three emission episodes with a total duration of ~380 s.
The first episode (from ~T0-1 to ~T0+15s) shows very bright
multi-peaked pulse with strong hard-to-soft spectral evolution.
The second episode is a single weak soft-spectrum pulse
from T0+135 to T0+175s. The third episode (from ~T0+195 to ~T0+380s)
also shows a single pulse, more intense and harder than the second one.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB130320_T48251/

As observed by Konus-Wind, the burst
had a total fluence of (7.8 � 0.3)x10-5 erg/cm2,
and a 64-ms peak flux, measured from T0+0.704s,
of (7.2 � 1.8)x10-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum (measured from T0 to T0+384.768 s)
is best fit in the 20 keV - 15 MeV range
by a simple power law with the photon index 2.24 � 0.03,
chi2 = 85.5/98 dof.

The spectrum at the onset of the burst (measured from T0 to T0+0.256 s)
is best fit in the 20 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -1.0 � 0.3,
the high energy photon index beta = -2.0 � 0.3,
the peak energy Ep = 340 � 190 keV,
chi2 = 23/25 dof.

The average spectrum of the second emission episode
(measured from T0+139.008 to T0+188.160 s)
is best fit in the 20 keV - 2 MeV range
by a power law with exponential cutoff model,
for which:
alpha = -1.7 � 0.3,
and Ep = 46 � 23 keV,
chi2 = 47/58 dof.

The average spectrum of the third emission episode
(measured from T0+294.656 to T0+384.768 s)
is best fit in the 20 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -1.23 � 0.17,
the high energy photon index beta = -2.25 � 0.19,
the peak energy Ep = 156 � 29 keV,
chi2 = 91.6/96 dof.


All the quoted results are preliminary.