TITLE: GCN CIRCULAR NUMBER: 15070 SUBJECT: GRB 130804A; Fermi GBM observation DATE: 13/08/06 00:21:07 GMT FROM: Hoi-Fung Yu at MPE Subject: GRB 130804A: Fermi GBM observation Hoi-Fung Yu (MPE), Adam Goldstein (ORAU/NASA MSFC) and Veronique Pelassa (UAH) report on behalf of the Fermi GBM Team: "At 00:33:15.53 UT on 04 August 2013, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 130804A (trigger 397269198 / 130804023). High peak flux from the GRB caused GBM to issue a repoint request that reoriented the satellite to place the GRB near the LAT boresight for 2.5 hours, subject to Earth limb contraints. The on-ground calculated location, using the GBM trigger data, is RA = 280.0, DEC = -76.2 (J2000 degrees, equivalent to 18h 40m, -76d 09'), with an uncertainty of 2.3 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 21 degrees. The GBM light curve consists of two main pulses with sub-structures, with a duration (T90) of about 0.96 s (50-300 keV). The time-averaged spectrum from T0-0.064 s to T0+1.024 s is adequately fit by a Band function with Epeak = 545 +/- 110 keV, alpha = -0.77 +/- 0.09, and beta = -2.22 +/- 0.31. The event fluence (10-1000 keV) in this time interval is (1.89 +/- 0.10)E-6 erg/cm^2. The 64 ms peak photon flux measured starting from T0-0.064 s in the 10-1000 keV band is 42.0 +/- 1.7 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."