GCN Circular 11952
Lin Lin (UAH) reports on behalf of the Fermi GBM Team: "At 22:42:11.73 UT on 20 April 2011, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 110420B (trigger 325032133 / 110420946). This burst was also detected by the Swift/BAT (Sbarufatti et al. 2011, GCN 11944). The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight is 123 degrees. The GBM light curve shows a fast rise slow decay peak, with a duration (T90) of about 0.048 s (50-300 keV). The time-averaged spectrum from T0-0.024 s to T0+0.040 s is well fit by a power law function with an exponential high-energy cutoff. The power law index is -0.12 +/- 0.31 and the cutoff energy, parameterized as Epeak, is 296.8 +/- 58.7 keV. The event fluence (10-1000 keV) in this time interval is (2.65 +/- 0.36)E-7 erg/cm^2. The 0.008-sec peak photon flux measured starting from T0-0.016 s in the 10-1000 keV band is 44.1 +/- 6.1 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."