GRB 120323A

David Gruber (MPE) and Valerie Connaughton (UAH)
report on behalf of the Fermi GBM Team:

"At 12:10:19.72 UT on 23 March 2012, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 120323A (trigger 354197421 / 120323507).

The on-ground calculated location, using the GBM trigger
data, is RA = 346.8, DEC = 27.2 (J2000 degrees,
equivalent to 23 h 07 m, 27 d 12 '), with an uncertainty
of 1 degree (radius, 1-sigma containment,
statistical only; there is additionally a systematic
error which is currently estimated to be 2 to 3 degrees).
(This location has been updated from an earlier GCN notice).

The angle from the Fermi LAT boresight is 43 degrees.
Moreover, this burst was bright enough to result in a Fermi spacecraft
autonomous rapid repoint (ARR) maneuver.

This burst was also independently detected by INTEGRAL SPI-ACS.

The GBM light curve consists of a very bright, double-peaked FRED-like pulse
with a duration (T90) of about 0.446 s (50-300 keV).
The time-averaged spectrum from T0-0.064 s to T0+0.512 s is
best fit by a Band function with Epeak = 64.8 +/- 3.8 keV,
alpha = -0.82 +/- 0.07, and beta = -2.01 +/- 0.02.

The event fluence (10-1000 keV) in this time interval is
(1.080 +/- 0.002)E-05 erg/cm^2. The 0.064-sec peak photon flux measured
starting from T0-0.064 s in the 10-1000 keV band
is 574.7 +/- 7.8 ph/s/cm^2. 
This peak flux is the highest of the mission to date.

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

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

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

V. Connaughton, M. Briggs, and C. Meegan, 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, and

A. von Kienlin, X. Zhang, V. Savchencko, and A. Rau, on behalf of the
INTEGRAL SPI-ACS GRB team, report:

The short-duration, very intense GRB 120323A has been observed by 
INTEGRAL (SPI-ACS), Fermi (GBM trigger 354197421: Gruber & Connaughton, 
GCN 13099
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 ), Konus-Wind, MESSENGER (GRNS), and Swift (BAT) so far, at 
about 43820 s UT (12:10:20). The burst was outside the coded field of 
view of the BAT.

We have triangulated it to a preliminary, 3 sigma error box whose 
coordinates are:
  ---------------------------------------------
   RA(2000), deg                 Dec(2000), deg
  ---------------------------------------------
  Center:
   340.407 (22h 41m 38s) +29.717 (+29d 43' 03")
  Corners:
   340.592 (22h 42m 22s) +30.058 (+30d 03' 29")
   340.405 (22h 41m 37s) +29.942 (+29d 56' 30")
   340.226 (22h 40m 54s) +29.374 (+29d 22' 27")
   340.410 (22h 41m 38s) +29.493 (+29d 29' 35")
  ---------------------------------------------
The error box area is 262 sq. arcmin, and its maximum
dimension is 45 arcmin.

This box may be improved.

The center of the GBM location (Gruber & Connaughton, GCN 13099
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 ) is 6.2 
deg from the center of the IPN box.

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 short very intense GRB 120323A
(Fermi/GBM detection: Gruber & Connaughton, GCN 13099
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 ;
IPN localization: Golenetskii at al., GCN 13102
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 )
triggered Konus-Wind at T0=43815.970s UT (12:10:15.970)

The light curve shows a double-headed FRED-like structure.
A total duration of the burst is ~0.5 s.
The emission is seen up to ~8 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB120323_T43815/

A spectral lag between hard G3(300-1400 keV) and soft G1(22-80 keV)
instrument's light curves is estimated to (-0.002 +/- 0.004) s.

As observed by Konus-Wind the burst
had a fluence of 1.03(-0.07,+0.07)x10-5 erg/cm2,
and a 16-ms peak flux, measured from T0+0.016 s,
of 7.2(-0.9,+0.9)x10-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The spectrum of the burst
(measured from T0 to T0+0.256 s)
is well fit in the 20 keV - 10 MeV range
by a power law with exponential cutoff model, for which
alpha = -1.57 (-0.07, +0.07),
and Ep = 331(-50, +64) keV,
chi2 = 45.8/42 dof.
Fitting this spectrum with the GRB (Band) function
gives an equally good result with the following model parameters:
the low-energy photon index alpha = -1.56 (-0.07, +0.09),
the high energy photon index beta = -2.9 (<-2.4),
the peak energy Ep = 317(-76, +68) keV,
chi2 = 44.3/41 dof.

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

P.H.T. Tam and A.K.H. Kong (NTHU) report:

We report on the Fermi/LAT observations of the short (~0.5s) and very
bright GRB 120323A
that triggered Fermi/GBM (Gruber & Connaughton, GCN 13099
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 ), Konus-Wind and
a few other detectors (Golenetskii at al., GCN 13102
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 ). Using the 10-degree
radius data centered on the IPN Triangulation position (GCN 13102
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 ), we did
not find any significant emission above 60 MeV from this circular region
during the prompt emission nor between 0.5 and 100 seconds after the
Konus-Wind
trigger time (T0).

Extrapolating the high-energy photon index, beta, which is 2.9, in the
best-fit
Band function (GCN 13103
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 ) to the LAT energy range, we derived 90% C.L.
upper
limits (0.1-10 GeV) for the following periods as tabulated below
(calculated
using Feldman & Cousins, 1998 formulation):

Epoch U.L. (ph/cm2-s)
T0 to T0+0.5s 3.5e-3
T0+0.5s to T0+1.0s 3.5e-3
T0+1.0s to T0+3.0s 8.7e-4
T0+3.0s to T0+10s 2.5e-5
T0+10s to T0+100s 1.3e-5

E. Gorbovskoy, V. Lipunov, V.Kornilov, D.Kuvshinov, A.Belinski, N.Tyurina,
N.Shatskiy, P.Balanutsa, D.Zimnukhov, A.Kuznetsov,  V.V.Chazov, 
A.Kuznetsov,
A.Sankovich
Sternberg Astronomical Institute, Moscow State University

K.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk
Irkutsk State University

V.Yurkov, Yu.Sergienko, D.Varda, E.Sinyakov
Blagoveschensk Educational State University, Blagoveschensk

A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Sennik
Kislovodsk Solar Station of the Pulkovo Observatory

V.Krushinski, I.Zalozhnich,  A. Popov, A. Bourdanov, A. Punanova
Ural Federal University

Hugo Levato and Carlos Saffe
Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)

Claudio Mallamaci, Carlos Lopez and Federico Podest
Observatorio Astronomico Felix Aguilar (OAFA)


MASTER II  robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
located in Tunka was pointed to the  GRB100423A  ~56.8 hours after GRB 
time at 2012-03-25 21:00:59 UT.
On our coad image (total exposure is 1620 s )  we haven`t found 
optical transient   within IPN error-box (Golenetskii et al., GCN No 13102)
The 5-sigma upper limit has been about 19.6 mag

The image is available at 
http://observ.pereplet.ru/images/GRB120323A/GRB120323A.jpg

The list of the known galaxies in IPN error box is:


   pgc   |        objname         | objtype |  mag   |   gal coord
---------+------------------------+---------+-------+-------+-------+---------+------------------------------------------------
  3967112 | 2MASXJ22410968+2946262 | g      | 17.38 | <(22h 41m 09.7s , +29d 46m 26s) , 00d 00m 04s>
  3967215 | 2MASXJ22412549+2942234 | g      | 18.73 | <(22h 41m 25.5s , +29d 42m 23s) , 00d 00m 04s>
  3967227 | 2MASXJ22412751+2958424 | g      | 17.09 | <(22h 41m 27.5s , +29d 58m 42s) , 00d 00m 04s>
  3967373 | 2MASXJ22415652+2929572 | g      | 16.18 | <(22h 41m 56.5s , +29d 29m 57s) , 00d 00m 04s>
  1869472 | PGC1869472             | G      |  17.2 | <(22h 42m 19.7s , +29d 32m 14s) , 00d 00m 33s>
  1873303 | PGC1873303             | G      | 16.44 | <(22h 41m 08.5s , +29d 39m 07s) , 00d 00m 54s>
  1881060 | PGC1881060             | G      | 17.24 | <(22h 41m 35.2s , +29d 51m 52s) , 00d 00m 35s>
  1884891 | PGC1884891             | G      | 16.69 | <(22h 42m 13.5s , +29d 57m 54s) , 00d 00m 37s>
  1888138 | PGC1888138             | G      | 17.61 | <(22h 41m 46.0s , +30d 02m 53s) , 00d 00m 30s>


The message may be cited.