TITLE: GCN CIRCULAR NUMBER: 14346 SUBJECT: GRB 130327B: Fermi GBM detection DATE: 13/03/28 03:35:36 GMT FROM: Vandiver Chaplin at UAH/Fermi-GBM V.Chaplin (UAH) and G. Fitzpatrick (UCD) report on behalf of the Fermi GBM Team: "At 08:24:04.05 UT on 27 March 2013, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 130327B (trigger 386065447 / 130327350), which was also detected by several instruments on-board the AGILE spacecraft (Del Monte et al. GCN 14344). The on-ground calculated location, using the GBM trigger data, is RA = 214.9, DEC = -74.6 degrees, with an uncertainty of 1 degree (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 at the GBM trigger time was 47 degrees. The Fermi Observatory executed a maneuver following this trigger and tracked the burst location for the next 2.5 hours, subject to Earth-angle constraints. The GBM light curve consists of multiple spikes on top of a gradual rise and decay. The main emission occurs between T0 and T0+35 seconds. The total duration (T90) is about 62 s (50-300 keV). The time-averaged spectrum from T0-0.8 s to T0+33 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.57 +/- 0.02 and the cutoff energy, parameterized as Epeak, is 341 +/- 6.3 keV. The spectrum also fits a Band function with Epeak = 334 +/- 7 keV, alpha = -0.56 +/- 0.02, and beta = -3.4 +/- 0.4. The event fluence (10-1000 keV) in this time interval is (5.176 +/- 0.057)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0+32.4 s in the 8-1000 keV band is 12.7 +/- 0.3 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."