TITLE: GCN CIRCULAR NUMBER: 8897 SUBJECT: GRB 090129: Fermi GBM detection DATE: 09/02/09 17:17:37 GMT FROM: Sylvain Guiriec at UAH S. Guiriec (UAH) reports on behalf of the Fermi GBM Team: "At 21:07:15.42 UT on 29 January 2009, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 090129 (trigger 254956037 / 090129880) which was also detected by the SWIFT-BAT. The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight is 22 degrees. The GBM light curve consists of a single peak with a FRED shape starting at ~T0-0.3s with a duration (T90) of about 17.2s (8-1000 keV). The time-averaged spectrum from T0-0.3s to T0+15.1s is well fitted by a Band function with Epeak = 123.2 +/- 44.8 keV, alpha = -1.39 +/- 0.13, and beta = -1.98 +/- 0.14 (chi squared 373 for 374 d.o.f.). The event fluence (8-1000 keV) in this time interval is (5.6 +/- 0.7)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+0.8 s in the 8-1000 keV band is 8.0 +/- 0.1 ph/s/cm^2. The spectral and temporal analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."