TITLE: GCN CIRCULAR NUMBER: 9473 SUBJECT: GRB 090529B: Fermi GBM detection DATE: 09/06/01 15:04:50 GMT FROM: Arne Rau at MPE Arne Rau (MPE) reports on behalf of the Fermi GBM Team: "At 07:26:22.41 UT on 29 May 2009, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 090529B (trigger 265274784 / 090529310). The on-ground calculated location, using the GBM trigger data, is RA = 231.2, DEC = +32.2 (J2000 degrees, equivalent to 15 h 25 m, 32 d 12 '), with an uncertainty of 7.2 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 36 degrees. The GBM light curve consists of a single peak with a duration (T90) of about 5.1 s (8-1000 keV). The time-averaged spectrum from T0-1.792 s to T0+5.376 s is best fit by a Band function with Epeak = 142 +/- 56 keV, alpha = -0.7 +/- 0.3, and beta = -2.0 +/- 0.3 (chi squared 561 for 544 d.o.f.). The event fluence (8-1000 keV) in this time interval is (3.4 +/- 0.9)E-07 erg/cm^2. The 1.28-sec peak photon flux measured starting from T0+0.003 s in the 8-1000 keV band is 4.1 +/- 0.1 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."