TITLE: GCN CIRCULAR NUMBER: 10539 SUBJECT: GRB 100322A: Fermi GBM detection DATE: 10/03/22 20:25:58 GMT FROM: Alexander van der Horst at NASA/MSFC A.J. van der Horst (NASA/MSFC/ORAU) and D. Tierney (UCD) report on behalf of the Fermi GBM Team: "At 01:05:09.64 UT on 22 March 2010, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 100322A (trigger 290912711 / 100322045). The on-ground calculated location, using the GBM trigger data, is RA=23.33, Dec=-10.22 (J2000 degrees, equivalent to 23h20m, -10d13'), with an uncertainty of 1.20 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 96 degrees. The GBM light curve consists of multiple peaks with a duration (T90) of 37.0 +/- 0.3 s (50-300 keV). The time-averaged spectrum from T0-1.0 s to T0+41.0 s is best fit by a Band function with Epeak = 309 +/- 16 keV, alpha = -0.88 +/- 0.02, and beta = -2.15 +/- 0.05 (Cstat 1095 for 602 d.o.f.). The event fluence (10-1000 keV) in this time interval is (6.13 +/- 0.04)E-5 erg/cm^2. The 1-sec peak photon flux measured starting from T0+1.1 s in the 10-1000 keV band is 16.1 +/- 0.3 ph/s/cm^2. The temporal and spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."