TITLE: GCN CIRCULAR NUMBER: 15503 SUBJECT: GRB 131118A: Fermi GBM detection DATE: 13/11/19 18:35:12 GMT FROM: Andrew Collazzi at NASA/MSFC/ORAU Andrew C. Collazzi (NASA/ORAU) reports on behalf of the Fermi GBM Team: "At 22:58:57.47 UT on 18 November 2013, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 131118A (trigger 406508340 / 131118.958). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 349.7, Dec = -69.4 (J2000 degrees, equivalent to J2000 23h 18.8m, -69° 24' ), with a statistical uncertainty of 1.0 degrees (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 150 degrees. Due to the high zenith angle of this burst, there may be higher than normal systematic errors on this location. This burst was also observed by Swift-BAT (ground analysis), Suzaku-WAM, and INTEGRAL/SPI-ACS. The GBM light curve shows a multi-peaked event with a duration (T90) of about 85 s (50-300 keV). The 1.024-s peak flux during this interval is 12.5 +/- 0.9 erg/s/cm^2 (10-1000 keV). The time-averaged spectrum from T0-13.8 to T0+99.8 s is equally well fit to a Comptonized model with Epeak = 370.5 +/- 10.6, alpha = -0.89 +/- 0.03 and a Band model with Epeak = 366.8 +/- 12.5, alpha = -0.89 +/- 0.03, and beta = -3.4 +/- 0.6. Both models yield a fluence (10-1000 keV) in this time interval of (9.2 +/- 0.1)E-05 erg/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."