//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15550 SUBJECT: IPN Triangulation of GRB 131126A (short/hard) DATE: 13/11/29 16:58:21 GMT FROM: Dmitry Svinkin at Ioffe Institute 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. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15551 SUBJECT: Konus-Wind observation of GRB 131126A DATE: 13/11/29 17:01:35 GMT FROM: Dmitry Frederiks at Ioffe Institute 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. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15572 SUBJECT: GRB 131126A: iPTF upper limits on the afterglow of a short GRB DATE: 13/12/03 19:24:27 GMT FROM: Leo Singer at CIT/PTF 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. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15573 SUBJECT: GRB 131126A: Fermi GBM observation DATE: 13/12/04 03:48:52 GMT FROM: Veronique Pelassa at UAH 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."