//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9865 SUBJECT: GRB 090902: Fermi GBM detection DATE: 09/09/02 16:44:07 GMT FROM: Elisabetta Bissaldi at MPE E. Bissaldi and A. von Kienlin (MPE) report on behalf of the Fermi GBM Team: "At 09:38:05.49 UT on 2 September 2009, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 090902 (trigger 273577087 / 090902401). The on-ground calculated location, using the GBM trigger data, is RA = 291.0, DEC = 53.1 (J2000 degrees, equivalent to 19h 24m, 53d 06'), with an uncertainty of 3.8 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 82 degrees. This burst was also independently detected by INTEGRAL SPI-ACS. The GBM light curve consists of a single peak with a duration (T90) of about 1.2 s (8-1000 keV). The time-averaged spectrum from T0-0.256 s to T0+0.896 s is best fit by a Band function with Epeak = 388 (+82/-102) keV, alpha = 0.30 (+0.5/-0.26), and beta = -2.05 (+0.29/-0.24) (chi squared 372 for 356 d.o.f.). The event fluence (8-1000 keV) in this time interval is (2.11 +/- 0.14)E-06 erg/cm^2. The 64-msec peak photon flux measured starting from T0+608 s in the 8-1000 keV band is 11.4 +/- 1.3 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."