GCN Circular 8902
A. von Kienlin (MPE) reports on behalf of the Fermi GBM Team: "At 04:56:42.56 UT on 17 February 2009, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 090217 (trigger 256539404/ 090217206). The on-ground calculated location, using the GBM trigger data, is RA = 211.9, DEC = -2.8 (J2000 degrees, equivalent to 14h 08m, -02d 48'), with an uncertainty of 1.0 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 34 degrees. This burst was also independently detected by INTEGRAL SPI-ACS. The GBM light curve shows one major structured peak with a duration (T90) of about 32.8 s (8-1000 keV) and (T50) of about 4.6 s (8-1000 keV). The time-averaged spectrum from T0+0.003 s to T0+19.584 s is well fit by a power law function with an exponential high energy cutoff. The power law index is -0.85 +/- 0.02 and the cutoff energy, parameterized as Epeak, is 626 +/- 29 keV (chi squared 631.30 for 482 d.o.f.). The event fluence (8-1000 keV) in this time interval is (3.08 +/- 0.03)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0+6.272 s in the 8-1000 keV band is 11.2 +/- 0.3 ph/s/cm^2. A Band function fits the spectrum equally well (chi squared 629.43 for 481d.o.f.) with Epeak= 610 +/- 32 keV, alpha = -0.845 +/- 0.023 and beta = -2.86 +/- 0.36. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."