GRB 131126A
GCN Circular 15550
Subject
IPN Triangulation of GRB 131126A (short/hard)
Date
2013-11-29T16:58:21Z (12 years ago)
From
Dmitry Svinkin at Ioffe Institute <svinkin@mail.ioffe.ru>
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,
K. Yamaoka, M. Ohno, Y. Hanabata, Y. Fukazawa, T. Takahashi, M. Tashiro,
Y. Terada, T. Murakami, and K. Makishima on behalf of the Suzaku WAM
team, and
K. Hurley on behalf of the IPN team, report:
The short-duration, hard spectrum, bright GRB 131126A has been observed
by Fermi (GBM: trigger 407130853) and Konus-Wind, so far, at about 14050
s UT (03:54:10).
We have triangulated it to a Konus-GBM annulus centered at
RA(2000)=219.687 deg (14h 38m 45s) Dec(2000)=-12.489 deg (-12d 29'
20"), whose radius is 65.710 �� 0.084 deg (3 sigma).
Combined with the GBM 1-sigma statistical+systematic error contour, this
constrains the arrival direction to that portion of the annulus between
RA, Dec = 206.1, +52.1 and 222.6, +53.2 degrees.
A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB131126_T14048/IPN/
The time history and spectrum will be given in forthcoming GCN Circulars.
GCN Circular 15551
Subject
Konus-Wind observation of GRB 131126A
Date
2013-11-29T17:01:35Z (12 years ago)
From
Dmitry Frederiks at Ioffe Institute <fred@mail.ioffe.ru>
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, bright GRB 131126A
(IPN Triangulation: Golenetskii et al., GCN 15550)
triggered Konus-Wind at T0=14048.270 s UT (03:54:08.270).
The burst light curve shows a pulse with a duration of ~140 ms.
The emission is seen up to ~6 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB131126_T14048/
As observed by Konus-Wind, the burst
had a fluence of (2.1 � 0.2)x10-6 erg/cm2,
and a 16-ms peak flux, measured from T0+0.016,
of (2.4 � 0.2)x10-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
The time-integrated spectrum
(measured from T0 to T0+0.128 s)
is best fit, in the 20 keV - 15 MeV range,
by a cutoff power law with the following model parameters:
the photon index alpha = -0.43 � 0.14
and the peak energy Ep = 633 � 85 keV,
chi2 = 46.2/65 d.o.f.
The spectrum near the maximum count rate
(measured from T0 to T0+0.064 s)
is best fit, in the 20 keV - 15 MeV range,
by a cutoff power law with the following model parameters:
the photon index alpha = -0.20 � 0.20
and the peak energy Ep = 680 � 100 keV,
chi2 = 40.6/60 d.o.f.
All the quoted results are preliminary.
GCN Circular 15572
Subject
GRB 131126A: iPTF upper limits on the afterglow of a short GRB
Date
2013-12-03T19:24:27Z (12 years ago)
From
Leo Singer at CIT/PTF <lsinger@caltech.edu>
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 131126A triggered Fermi GBM (Fermi trigger
407130853) at 2013-11-26 03:54:10 and was localized by IPN using
Fermi and Konus-Wind (Golenetskii et al., GCN 15550; Golenetskii
et al., GCN 15551).
Starting 2013-11-26 10:50:40, we imaged about 60 deg^2 surrounding
the trigger's localization using the Palomar 48-inch Oschin telescope
(P48), covering most of the GBM 1-sigma statistical+systematic error
region and most of its intersection with the IPN Fermi-Konus 3-sigma
annulus. Sifting through candidate variable sources using standard
iPTF vetting procedures, we find no afterglow candidates to an
average limiting magnitude of R~19.5 at 7 hours after the burst.
See http://www.its.caltech.edu/~lsinger/iptf/Fermi407130853.pdf for
a diagram of the PTF fields observed in relation to the Fermi and
IPN localizations.
GCN Circular 15573
Subject
GRB 131126A: Fermi GBM observation
Date
2013-12-04T03:48:52Z (12 years ago)
From
Veronique Pelassa at UAH <vero.pelassa@gmail.com>
V. Pelassa and C. Meegan (UAH) report on behalf of the Fermi GBM Team:
"At 03:54:10.43 UT on 26 November 2013, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 131126A (trigger 407130853 / 131126163)
which was also detected by Konus/Wind (Golenetskii et al 2013, GCN 15551)
leading to an IPN Konus/GBM annulus (Golenetskii et al 2013, GCN 15550).
The angle from the Fermi LAT boresight is 108 degrees.
iPTF also performed a tiled observation of the localization error box and
established an upper limit on the GRB afterglow (Singer et al 2013, GCN 15572).
The GBM light curve consists of a single pulse with a duration (T90)
of about 0.3 s (50-300 keV).
The time-averaged spectrum from T0-0.064 s to T0+0.256 s is
adequately fit by a power law function with an exponential
high-energy cutoff. The power law index is -0.06 +/- 0.13 and
the cutoff energy, parameterized as Epeak, is 600 +/- 62 keV
(Castor statistics 397.51 for 364 d.o.f.).
A Band function fits the spectrum equally well (Castor statistics 391.35
for 363 d.o.f.) with Epeak= 489 +/- 74 keV, alpha = 0.13 +/- 0.20
and beta = -2.29 +/- 0.26.
The event fluence (10-1000 keV) in this time interval is
(2.0 +/- 0.1)E-06 erg/cm^2. The 64-msec peak photon flux measured
starting from T0+0.000 s in the 10-1000 keV band
is 36 +/- 2 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."