GCN Circular 9020
P. N. Bhat (UAH) report on behalf of the Fermi GBM Team: At 19:13:46.10 UT on 20 March 2009, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 090320B (trigger 259269228 / 090320801). The on-ground calculated location, using the GBM trigger data, is RA = 183.8, DEC = 57.6 (J2000 degrees, equivalent to 12 h 15.3 m, 57 d 33 '), with an uncertainty of 9.6 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 101 degrees. The GBM light curve shows one main pulse with several weaker trailing pulses with a duration (T90) of about 52 s (8-1000 keV). The time-averaged spectrum from T0-7.4 s to T0+52 s is adequately fit by a power law function with an exponential high energy cutoff. The power law index is -1.1 +/- 0.3 and the cutoff energy, parameterized as Epeak, is 72 +/- 14 keV (chi squared 255 for 237 d.o.f.). The event fluence (8-1000 keV) in this time interval is (1.1 +/- 0.3)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0 s in the 8-1000 keV band is 0.12 +/- 0.04 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."