GCN Circular 9336
S. Guiriec, V. Connaughton and M. Briggs (UAH) report on behalf of the Fermi GBM Team: "At 00:22:59.97 UT on 2009 May 10, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 090510 (trigger 263607781 / 090510016) which was also detected by the Swift-BAT (Hoversten et al. 2009, GCN 9331) and the Fermi-LAT (Ohno et al. 2009, GCN 9334). The GBM position is consistent with those reported by Swift and the LAT. The GBM triggered on a precursor lasting 30 ms followed 0.4 s later by an intense and hard emission period of 0.5 s and a tail lasting a further 0.5 s. The intense period has several narrow peaks and its integrated spectrum is well fit by a Band function with alpha = -0.80 +/- 0.03, beta = 2.6 +/- 0.3 and EPeak = 4.4 +/- 0.4 MeV. The peak flux on a 64 ms timescale between 8 keV and 40 MeV was measured 0.55 s after the trigger to be 80 ph.cm^-2.s^-1. The 8 keV to 40 MeV fluence in the 0.512 s long period of intense emission is (3.0 � 0.2) E-5 erg.cm^-2. The spectral analysis results presented above are preliminary; further analysis is on-going."