TITLE: GCN CIRCULAR NUMBER: 13339 SUBJECT: GRB 120521B: Fermi GBM observation DATE: 12/05/23 09:16:58 GMT FROM: David Gruber at MPE David Gruber (MPE) reports on behalf of the Fermi GBM Team: "At 09:07:52.39 UT on 21 May 2012, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 120521B (trigger 359284074 / 120521380). which was also detected by the Swift/BAT (Krimm et al. 2012, GCN 13317) The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight is 84 degrees. The GBM light curve consists of a single pulse with a duration (T90) of about 91 s (50-300 keV). The time-averaged spectrum from T0-5 s to T0+29 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.34 +/- 0.20 and the cutoff energy, parameterized as Epeak, is 213 +/- 29 keV The event fluence (10-1000 keV) over the T90 time interval is (3.11 +/- 0.07)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+2.4 s in the 10-1000 keV band is 1.55 +/- 0.23 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."