TITLE: GCN CIRCULAR NUMBER: 9419 SUBJECT: GRB 090518: Fermi GBM detection DATE: 09/05/22 16:29:30 GMT FROM: Bill Paciesas at UAH W. Paciesas (UAH) reports on behalf of the Fermi GBM Team: "At 01:54:44.52 UT on 18 May 2009, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 090518 (trigger 264304486 / 090518080). which was also detected by the SWIFT-BAT (Evans et al. 2009, GCN 9386) The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight is 53 degrees. The GBM light curve consists of a single asymmetric peak with a duration (T90) of about 9 s (8-1000 keV). The time-averaged spectrum from T0-2.048 s to T0+7.04 s is adequately fit by a simple power law function with index -1.59 +/- 0.06 (chi squared 688 for 688 d.o.f.). The event fluence (8-1000 keV) in this time interval is (1.60 +/- 0.05)E-6 erg/cm^2. The 1-sec peak photon flux measured starting from T0-0.64 s in the 8-1000 keV band is 4.7 +/- 0.1 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."