GRB 131125A

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

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

K. Hurley on behalf of the IPN team, report:

The short-duration, hard spectrum GRB 131125A has been observed by Fermi 
(GBM: trigger 407089974), INTEGRAL (SPI-ACS), and Konus-Wind, so far, at 
about 59571 s UT (16:32:51).

We have triangulated it to a preliminary, 3 sigma error box whose 
coordinates are:
  ---------------------------------------------
   RA(2000), deg                 Dec(2000), deg
  ---------------------------------------------
  Center:
   114.675 (07h 38m 42s) +48.414 (+48d 24' 49")
  Corners:
   114.485 (07h 37m 56s) +45.684 (+45d 41' 01")
   115.166 (07h 40m 40s) +45.939 (+45d 56' 21")
   114.817 (07h 39m 16s) +51.137 (+51d 08' 15")
   114.077 (07h 36m 18s) +50.873 (+50d 52' 22")
  ---------------------------------------------
The error box area is 2.5  sq. deg, and its maximum
dimension is 5.5 deg (the minimum one is 29 arcmin).
The Sun distance was 130 deg.

This box may be improved.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB131125_T59571/IPN/

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

S. Golenetskii, R.Aptekar, D. Frederiks, V. Pal'shin,
P. Oleynik, M. Ulanov, D. Svinkin, and T. Cline, on behalf
of the Konus-Wind team, report:

The short-duration, hard-spectrum GRB 131125A
(IPN Triangulation: Golenetskii et al. GCN 15546
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 )
triggered Konus-Wind at T0=59572.927 s UT (16:32:52.927).

The burst duration is ~0.5 s.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB131125_T59572/

As observed by Konus-Wind, the burst
had a fluence of (1.3 � 0.2)x10-6 erg/cm2,
and a 64-ms peak flux, measured from T0-0.064,
of (5.7 � 1.2)x10-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The 3-channel time-integrated spectrum
(measured from T0-0.448 to T0+0.064 s)
can be modeled, in the 22 keV - 1.3 MeV range,
by the cutoff power law with the following model parameters:
the photon index alpha = 0.00 � 0.13,
and the peak energy Ep = 638 � 62 keV.

The 3-channel spectrum at the maximum count rate
(measured from T0-0.064 s to T0)
can be modeled, in the 22 keV - 1.3 MeV range,
by the cutoff power law with the following model parameters:
the photon index alpha = +0.2 � 0.3,
and the peak energy Ep = 665 � 113 keV.

All the quoted results are preliminary.

L. P. Singer (Caltech), M. M. Kasliwal (Carnegie Observatories), and
S. B. Cenko (NASA/GSFC) report on behalf of the intermediate Palomar
Transient Factory (iPTF) collaboration:

The short-hard GRB 131125A triggered Fermi GBM (Fermi trigger 407089974)
at 2013-11-25 16:32:47 and was localized by IPN using Fermi, INTEGRAL,
and Konus-Wind (Golenetskii et al., GCN 15546
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 ).

Starting 2013-11-26 04:16 UT, we imaged about 95 deg^2 surrounding the
Fermi GBM localization, covering most of the intersection between the
GBM 1-sigma statistical+systematic error contour and the IPN Fermi-INTEGRAL
3-sigma annulus, also including the entire intersection with the Fermi-Wind
annulus. Using standard iPTF vetting procedures including Palomar 60-inch
follow-up, we find no afterglow candidates to an average limiting magnitude
of R~20.4 at 11.8 hours after the burst.

See http://www.its.caltech.edu/~lsinger/iptf/Fermi407089974.pdf for a
diagram of the PTF fields observed in relation to the Fermi and IPN
localizations.

Gorbovskoy, V. Lipunov,D.Denisenko, V.Kornilov, D.Kuvshinov,  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.Krushinsky, I.Zalozhnih,  A. Popov
Ural Federal University, Yekaterinburg, Kourovka

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 Kislovodsk was pointed to the  GRB131125A 10 s after notice 
time and 24 sec after GRB time at 2013-11-25 16:33:25 UT.
But IPN  error box (GCN 15546
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 ) was outside of FOV of our MASTER-II 
telescope and very wide field camera (usually we follow up all Fermi 
alerts).

After first coordinates specification we cover IPN error box using very 
wide field cameras. The first images covered  error-box was obtained 49 
sec after GRB time at 2013-11-25 16:33:40 UT.
The 5-sigma upper limit has been about 12 mag on single 5 seconds exposure 
images and 13.5 on coadd of first 14 consecutive images
The 5-sigma upper limit has been about 14.1 mag
We find several optical marginal candidates to OT.

Name        R.A.           Dec.      m
MASTER_1  114.775649     46.120371   13.6
MASTER_2  114.597740     48.927898   13.7
MASTER_3  114.835195     47.047021   13.0

One sigma coordinate error is +- 7 arcsec.

The first image available here:
http://master.sai.msu.ru/static/GRB/GRB131125_first.jpeg

The coadd images here:
http://master.sai.msu.ru/static/GRB/GRB131125_coadd.jpeg

The message may be cited.