GCN Circular 9428
P. N. Bhat (UAH) report on behalf of the Fermi GBM Team: "At 20:23:19.31 UT on 20 May 2009, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 090520C (trigger 264543801 / 090520850). The on-ground calculated location, using the GBM trigger data, is RA = 111.2, DEC = -19.7 (J2000 degrees, equivalent to 07 h 24.8 m, -19 d 42'), 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 71 degrees. The GBM light curve consists of single peak with a duration (T90) of about 4.9 s (10-1000 keV). The time-averaged spectrum from T0-0.512 s to T0+3.968 s is adequately fit by a Band function with Epeak = 204.2 +/- 27.9 keV, alpha = -0.73 +/- 0.09, and beta = -1.96 +/- 0.10 (chi squared 400.9for 362 d.o.f.). The event fluence (8-1000 keV) in this time interval is (3.54 +/- 0.25)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+0.872 s in the 8-1000 keV band is 4.47 +/- 0.32 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."