GCN Circular 10714
Dave Tierney (UCD) and Sheila McBreen (UCD/MPE) report on behalf of the Fermi GBM Team: "At 13:18:03.89 UT on 03 May 2010, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 100503A (trigger 294585485 / 100503554). The on-ground calculated location, using the GBM trigger data, is RA = 147.5, DEC = 4.0 (J2000 degrees, equivalent to 09 h 50 m, 4 d 0 '), with an uncertainty of 1.5 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 63 degrees. The GBM light curve consists of multiple peaks with a duration (T90) of 129.5 +/- 9.9 s (50-300 keV). The time-averaged spectrum from T0-4 s to T0+52 s is best fit by a power law function with an exponential high energy cutoff. The power law index is -0.99 (+0.06/-0.05) and the cutoff energy, parameterized as Epeak, is 211.60 (+18.30/-15.50) keV (Cstat 877 for 601 d.o.f.). The event fluence (10-1000 keV) in this time interval is (1.23 +/- 0.03)E-5 erg/cm^2. The 1-sec peak photon flux measured starting from T0+46.5 s in the 10-1000 keV band is 5.8 +/- 0.2 ph/s/cm^2. A Band function fits the spectrum equally well (Cstat 871 for 600 d.o.f.) with Epeak= 162.60 (+21.60/-17.00) keV, alpha = -0.85 (+0.09/-0.09) and beta = -2.24 (+0.13/-0.21). The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."