GCN Circular 10811
Arne Rau (MPE) and Alexander van der Horst (UAH) report on behalf of the Fermi GBM Team: "At 01:48:01.11 UT on 28 May 2010, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 100528A (trigger 296704083 / 100528075) which was also detected by the SuperAGILE (Del Monte et al. 2010, GCN 10810). The GBM on-ground location is consistent with the SuperAGILE position. The angle from the Fermi LAT boresight is 53 degrees. The GBM light curve shows a main peak followed by a fainter second pulse with a duration (T90) of about 24.6 +/- 0.5s (50-300 keV). The time-averaged spectrum from T0+0.003 s to T0+24.576 s is best fit by a Band function with Epeak = 316.5 +/- 17.8 keV, alpha = -1.16 +/- 0.02, and beta = -1.99 +/- 0.06 (CSTAT 1868.5 for 657 d.o.f.). The event fluence (10-1000 keV) in this time interval is (2.77 +/- 0.02) E-05 erg/cm^2. The 1.024-sec peak photon flux measured starting from T0+8.576 s in the 10-1000 keV band is 14.76 +/- 0.21 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."