Gamma-ray Burst 120323A
(All information courtesy of the instrument teams.)
Previous IAU Circulars
Results of Observations
- GCN Circular #13099
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."
- GCN Circular #13102
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
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), 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
RA(2000), deg Dec(2000), deg
340.407 (22h 41m 38s) +29.717 (+29d 43' 03")
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) is 6.2
deg from the center of the IPN box.
- GCN Circular #13103
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;
IPN localization: Golenetskii at al., GCN 13102)
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
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.
- GCN Circular #13104
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), Konus-Wind and
a few other detectors (Golenetskii at al., GCN 13102). Using the 10-degree
radius data centered on the IPN Triangulation position (GCN 13102), 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
trigger time (T0).
Extrapolating the high-energy photon index, beta, which is 2.9, in the
Band function (GCN 13103) to the LAT energy range, we derived 90% C.L.
limits (0.1-10 GeV) for the following periods as tabulated below
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
- GCN Circular #13116
E. Gorbovskoy, V. Lipunov, V.Kornilov, D.Kuvshinov, A.Belinski, N.Tyurina,
N.Shatskiy, P.Balanutsa, D.Zimnukhov, A.Kuznetsov, V.V.Chazov,
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
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.
- 1210.7252 from 30 Oct 12
S. Guiriec et al.: Evidence for a Photospheric Component in the Prompt Emission of the Short GRB120323A and its Effects on the GRB Hardness-Luminosity
The short GRB 120323A had the highest flux ever detected with the Fermi/GBM. Here we study its remarkable spectral properties and their
evolution using two spectral models: (i) a single emission component scenario, where the spectrum is modeled by the empirical Band function,
and (ii) a two component scenario, where thermal (Planck-like) emission is observed simultaneously with a non-thermal component (a Band
function). We find that the latter model fits the integrated burst spectrum significantly better than the former, and that their respective
spectral parameters are dramatically different: when fit with a Band function only, the Epeak of the event is unusually soft for a short GRB,
while adding a thermal component leads to more typical short GRB values. Our time-resolved spectral analysis produces similar results. We argue
here that the two-component model is the preferred interpretation for GRB 120323A, based on: (i) the values and evolution of the Band function
parameters of the two component scenario, which are more typical for a short GRB, and (ii) the appearance in the data of a significant
hardness-intensity correlation, commonly found in GRBs, when we employee two-component model fits; the correlation is non-existent in the
Band-only fits. GRB 110721A, a long burst with an intense photospheric emission, exhibits the exact same behavior. We conclude that GRB 120323A
has a strong photospheric emission contribution, first time observed in a short GRB. Magnetic dissipation models are difficult to reconcile
with these results, which instead favor photospheric thermal emission and fast cooling synchrotron radiation from internal shocks. Finally, we
derive a possibly universal hardness-luminosity relation in the source frame using a larger set of GRBs L,i=(1.59+/-0.84).10^50
(Epeak,i)^(1.33+/-0.07) erg/s), which could be used as a possible redshift estimator for cosmology.
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Jochen Greiner, last update: 30-Oct-2012