TITLE: GCN CIRCULAR NUMBER: 18861 SUBJECT: GRB 160113A: Fermi GBM detection DATE: 16/01/14 00:57:55 GMT FROM: Eric Burns at U of Alabama O.J. Roberts (UCD) and E. Burns(UAH) report on behalf of the Fermi GBM Team: "At 09:32:30.52 UT on 13 January 2016, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 160113A (trigger 474370354 / 160113398). The on-ground calculated location, using the GBM trigger data, is RA = 187.3, DEC = 11.5, with an uncertainty of 1.2 degrees (radius, 1-sigma containment, statistical only; there is additionally a systematic error which we have characterized as a core-plus-tail model, with 90% of GRBs having a 3.7 deg error and a small tail suffering a larger than 10 deg systematic error. [Connaughton et al. 2015, ApJS, 216, 32] ). All of the optically variable sources detected by iPTF (Singer, GCN 18859) are contained in the uncertainty region surrounding the final location. The angle from the Fermi LAT boresight at the GBM trigger time is 98 degrees. The GBM light curve consists of a smaller peak between T-5 and T+10 followed by a bright peak from T+20 to about T+60 with a duration (T90) of about 25 s (50-300 keV). The time-averaged spectrum from T0+25.60 s to T0+51.20 s is best fit by a Band function with Epeak = 98 +/- 1 keV, alpha = -0.40 +/- 0.03, and beta = -3.16 +/- 0.11 The event fluence (10-1000 keV) in this time interval is (3.12 +/- 0.04)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0+31.51 s in the 10-1000 keV band is 27.7 +/- 0.5 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."