GCN Circular 11831
A. von Kienlin (MPE) reports on behalf of the Fermi GBM Team: "At 12:29:19.19 UT on 28 March 2011, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 110328B (trigger 323008161 / 110328520). The on-ground calculated location, using the GBM trigger data, is RA = 121.1, DEC = 45.8 (J2000 degrees, equivalent to 8h 4m, 45d 48'), with an uncertainty of 1.2 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 31 degrees. This burst was also independently detected by INTEGRAL SPI-ACS. The GBM light curve consists of a single pulse with a duration (T90) of about 120 s (50-300 keV). The time-averaged spectrum from T0+0.003 s to T0+122.882 s is well fit by a power law function with an exponential high-energy cutoff. The power law index is -1.17 (+0.04/-0.04) and the cutoff energy, parameterized as Epeak, is 538 (+96/-70) keV. The event fluence (10-1000 keV) in this time interval is (2.6 +/- 0.1)E-05 erg/cm^2. The 1.024-sec peak photon flux measured starting from T0+4.93 s in the 10-1000 keV band is 5.8 +/- 0.3 ph/s/cm^2. A Band function fits the spectrum equally well with Epeak = 369 (+115/-69) keV, alpha = -1.11 +/-0.06 and beta = -1.94 (+0.10/-0.22). The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."