GRB 100829A

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

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

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

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

and

D. M. Smith, R. P. Lin, J. McTiernan, R. Schwartz, C. Wigger, and W.
Hajdas, on behalf of the RHESSI GRB team, report:


Fermi (GBM), Konus-Wind, Swift (BAT),  MESSENGER (GRNS), and RHESSI
observed the very bright GRB 100829A at about 75729 s UT (21:02:09) (the 
Fermi/GBM trigger 304808530). The burst was outside the coded field of 
view of the BAT.

We have triangulated this burst to the following 3 sigma error box:
-----------------------------------------------
      RA(2000), deg              Dec(2000), deg
-----------------------------------------------
Center:
   90.409 (06h 01m 38s)   +30.314 (+30d 18' 49")
Corners:
   90.335 (06h 01m 20s)   +29.523 (+29d 31' 22")
   90.353 (06h 01m 25s)   +30.317 (+30d 19' 02")
   90.490 (06h 01m 58s)   +31.121 (+31d 07' 16")
   90.464 (06h 01m 51s)   +30.310 (+30d 18' 37")
-----------------------------------------------

The error box area is 278 sq. arcmin.
The maximum distance between the box corners is 1.6 deg.
This error box may be improved.

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 bright GRB 100829A, (localized by IPN:
Golenetskii et.al, GCN 11199
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 )
triggered Konus-Wind at T0=75727.937s UT (21:02:07.937)

The burst light curve started with a bright complex
~2.5s-long structure, followed by a weaker emission
episode at T0 + 6 s. The total duration of the burst is ~10 s.
The emission is seen up to 1.5 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB100829_T75727/

As observed by Konus-Wind the burst
had a fluence of (1.40 � 0.15)x10-5 erg/cm2,
and a 16-ms peak flux, measured from T0+1.472s,
of (2.4 � 0.6)x10-5 erg/cm2/s
(both in the 20 keV - 2 MeV energy range).

The time-integrated spectrum of the burst
(from T0 to T0+10.240 s) is best fit
in the 20 keV - 2 MeV range by a power law
with exponential cutoff model, for which
alpha = -1.44(-0.12, +0.14),
and Ep = 278(-47, +73) keV (chi2 = 36.2/61 dof).

Fitting this spectrum by the GRB (Band) model
yields to the same values of alpha and Ep, with
beta = -9.4 (<-2.3), chi2 = 36.2/60 dof.

The spectrum at the maximum count rate
(measured from T0+0.256 to T0+2.048 s) is best fit
in the 20 keV - 2 MeV range by the GRB (Band)
model, for which:
the low-energy photon index alpha = -0.90 (-0.17, +0.35),
the high energy photon index beta = -2.7 (<-2.2),
the peak energy Ep = 263(-71, +56) keV (chi2 = 48.5/51 dof).

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

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

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


V.Yurkov, Yu.Sergienko, D.Varda, I.Kudelina
Blagoveschensk Educational State University, Blagoveschensk


V.Krushinski, I.Zalozhnich, T.Kopytova, A. Popov
Ural State University, Kourovka

K.Ivanov, S.Yazev, N.M.Budnev, E.Konstantinov, V.Lenok, O.Gres, O.Chuvalaev, 
V.Poleschuk
Irkutsk State University

As we  wroute (Gorbovskoy et. al., GCN CIRCULAR N11157) MASTER   robotic 
telescopes 
(MASTER-Net: http://observ.pereplet.ru, 6 Very Wide Field cameras and 2 
Wide Field Telescopes ) located  near Kislovodsk  was pointed to the FERMI 
GRB 100829A (FERMI Trigger N 304808530 ) 
30  sec  after Notice time and 44 s after trigger time.

Unfortunately error box from IPN Triangulation of the very bright GRB 
100829A (Golenetskii et al., GCN Circ N11199) very near horizont (see 
image http://observ.pereplet.ru/images/GRB100829A/WFC_FOW.jpg ).

mailto: lipunov@sai.msu.ru