GRB 101123A

Sylvain Guiriec (UAH)
reports on behalf of the Fermi GBM Team:

At 22:51:34.97  UT on 23 November 2010, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 101123A (trigger 312245496 / 101123952).

The on-ground calculated location, using the GBM trigger
data, is RA = 131.24, DEC = 6.51 (J2000 degrees,
equivalent to 08 h 54 m 27 s,  06 d 30 ' 36 ''), 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).

The angle from the Fermi LAT boresight is 86 degrees.

GBM triggered on a weak pulse followed by three separate emission periods
with a total duration (T90) of about 105 s (50-300 keV).
The time-averaged spectrum of the brightest part of the burst from T0+42 s
 to T+57 s is adequately fit by a Band function with Epeak = 476 +/- 11 keV,
alpha = -0.75 +/- 0.01, and beta = -2.14 +/- 0.03.

The event fluence (10-1000 keV) over the T90 duration is
(1.283 +/- 0.006)E-4 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+51.7 s in the 8-1000 keV band is 49 +/- 2 ph/s/cm^2.

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

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

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

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

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

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

A. von Kienlin, G. Lichti, and A. Rau, on behalf of the
INTEGRAL SPI-ACS GRB team,

E. Del Monte, E. Costa, I. Donnarumma, Y. Evangelista, M. Feroci,
I. Lapshov, F. Lazzarotto, L. Pacciani, M. Rapisarda, P. Soffitta,
on behalf the SuperAGILE team,

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

and

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

Fermi (GBM), INTEGRAL (SPI-ACS), AGILE (MiniCalorimeter and
SuperAGILE), Swift (BAT), Konus-Wind, MESSENGER (GRNS), and Mars Odyssey 
(HEND) observed the bright GRB 101123A at about 22:52:14 UT (the 
Fermi/GBM trigger 312245496: Guiriec, GCN 11423
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 ). The burst was outside 
the coded fields of view of the BAT and SuperAGILE.

We have triangulated this burst to the following 3 sigma error box:
-----------------------------------------------
     RA(2000), deg              Dec(2000), deg
-----------------------------------------------
Center:
  131.381 (08h 45m 32s)   + 5.563 (+05d 33' 47")
Corners:
  130.942 (08h 43m 46s)   + 4.586 (+04d 35' 11")
  131.755 (08h 47m 01s)   + 6.277 (+06d 16' 35")
  131.827 (08h 47m 18s)   + 6.584 (+06d 35' 02")
  131.011 (08h 44m 03s)   + 4.873 (+04d 52' 23")
-----------------------------------------------

The error box area is 433 sq. arcmin.
The maximum distance between the box corners is 2.2 deg.
This error box may be improved.

A map is posted at http://ssl.berkeley.edu/ipn3/101123A
showing the GBM best-fit position (blue star), and the IPN annuli (solid
lines with centers dot-dashed).

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 bright GRB 101123A (Fermi/GBM
trigger 312245496 / 101123952: Guiriec, GCN 11423
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 ;
localized by IPN: Hurley et al., GCN 11424
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 )
triggered Konus-Wind at T0=82338.387s UT (22:52:18.387)

The burst light curve contains three main bursting
episodes with a total duration of ~120 s.
The emission is seen up to ~10 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB101123_T82338/

As observed by Konus-Wind the burst
had a fluence of (2.5 � 0.3)x10-4 erg/cm2,
and a 64-ms peak flux, measured from T0+9.984s,
of (1.9 � 0.3)x10-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum of the burst
(measured from T0 to T0+118.272 s) is best fit
in the 20 keV - 10 MeV range by the GRB (Band) model,
for which:
the low-energy photon index alpha = -0.9 (+/-0.1),
the high energy photon index beta = -2.1 (-0.2, +0.1),
the peak energy Ep = 449(-66, +83)keV (chi2 = 100/84 dof).

The spectrum at the maximum count rate
(measured from T0+9.984 to T0+11.776 s) is best fit
in the 20 keV - 10 MeV range by a power law
with exponential cutoff model, for which
alpha = -0.81(+/-0.08),
and Ep = 574(-52, +60) keV (chi2 = 69/62 dof).
Fitting this spectrum by the GRB (Band) model
yields to the same values of alpha and Ep, with
only an upper limit for beta (< -3.3)

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

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

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

MASTER II  robotic telescope (MASTER-Net: http://observ.pereplet.ru, 2x400 
mm, 2x4 square degrees)  located at 
Kislovodsk and 6 very wide field cameras (420 square degrees)was pointed 
to the long bright  GRB101123A (Fermi/GBM trigger 312245496 / 101123952: 
Guiriec, GCN 11423
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 ; localized by IPN: Hurley et al., GCN 11424
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 ) 23 
sec after  notice time and 39 sec  after trigger under Moon light 
with some haze.

After some repointing and imaging due to  continuously
  updating GRB socket position 
robotic telescope was made several frames at IPN error box (Hurley et 
al., GCN 11424
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 ).

The first 2 telescope images (20 sec exp. time) covered 90%  IPN error 
box was maded 111 sec after GRB.

The 3-sigma upper limit has been about 15.0 (telescopes) and 10.0 (wide 
field cameras).
There is no OT brighter 10 mag on Very Wide Field Cameras.
Robot find two merginally OT candidates on telescope images:

OT   Date        Time       Ra             Dec           Mag(R)
1. 2010-11-23 22:53:25 08h 45m 06.61s , +05d 14m 47s.1   14.3
2. 2010-11-23 22:55:28 08h 45m 52.58s , +05d 48m 00s.4   13.2

However both transients are visible only on single image.
The images, OT candidates and map of the error boxes position  are 
available at 
http://observ.pereplet.ru/images/GRB101123A/grb.html  .

The message may be cited.

mailto: lipunov@sai.msu.ru

W. Zheng, S. B. Pandey and C. Akerlof (U Mich), report on behalf of
the ROTSE collaboration:

ROTSE-IIIc, located at the H.E.S.S. site at Mt. Gamsberg, Namibia,
responded to GRB 101123A (Fermi/GBM trigger 312245496 / 101123952: 
Guiriec, GCN 11423
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 ; localized by IPN: Hurley et al., GCN 11424
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 )
107s after the burst. Observation was performed in 2x2 tiling mode,
covered totally ~3.6x3.6 square degrees around the center of GBM
trigger. Observation lasted for ~1.3 hours with 20s exposure time
for each image.

The location of the two OT candidates reported by Gorbovskoy et al.
(GCN 11426
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 ) were both covered by ROTSE images.
For candidate 1, the first ROTSE image was started at
2010-11-23 22:54:50.91, 196s after the burst.
For candidate 2, the first ROTSE image was started at
2010-11-23 22:53:51.31, 136s after the burst.

We do not detected any point source at either of the two candidate
locations in the single or the co-added images. The limiting
magnitude is ~16.0 mag for single image and ~16.7 mag for co-added
images.