TITLE: GCN CIRCULAR NUMBER: 9474 SUBJECT: GRB 090529C: Fermi GBM detection DATE: 09/06/01 15:09:17 GMT FROM: Arne Rau at MPE Arne Rau (MPE) reports on behalf of the Fermi GBM Team: "At 13:32:00.49 UT on 29 May 2009, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 090529C (trigger 265296722 / 090529564). The on-ground calculated location, using the GBM trigger data, is RA = 162.7, DEC = 47.3 (J2000 degrees, equivalent to 10 h 51 m, 47 d 18 '), 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 69 degrees. This burst was also independently detected by INTEGRAL SPI-ACS. The GBM light curve consists of two narrow pulses with a duration (T90) of about 10.4 s (8-1000 keV). The time-averaged spectrum from T0-0.002 s to T0+10.048 s is best fit by a Band function with Epeak = 188 +/- 15 keV, alpha = -0.84 +/- 0.05, and beta = -2.1 +/- 0.1 (chi squared 795 for 648 d.o.f.). The event fluence (8-1000 keV) in this time interval is (3.1 +/- 0.1)E-06 erg/cm^2. The 1.028-sec peak photon flux measured starting from T0+9.024 s in the 8-1000 keV band is 25 +/- 1 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog. We further report that the Fermi Observatory executed a maneuver following this trigger and tracked the burst location for the next 5 hours, subject to Earth-angle constraints. "