TITLE: GCN CIRCULAR NUMBER: 8853 SUBJECT: GRB 090126B: Fermi GBM detection DATE: 09/01/26 16:31:43 GMT FROM: Andreas von Kienlin at MPE A. von Kienlin (MPE) reports on behalf of the Fermi GBM Team: "At 05:26:22.23 UT on 26 January 2009, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 090126B (trigger 254640384 / 090126227 ). The on-ground calculated location, using the GBM trigger data, is RA = 190.5, DEC = 33.2 (J2000 degrees, equivalent to 19h 42m, 33d 12'), with an uncertainty of 4.4 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 18 degrees. The GBM light curve consists of a single peak with a duration (T90) of about 10.8 s (8-1000 keV). The time-averaged spectrum from T0-4.608 s to T0+5.632 s is best fit by a power law function with an exponential high energy cutoff. The power law index is -0.99 +/- 0.18 and the cutoff energy, parameterized as Epeak, is 47.5 +/- 3.4 keV (chi squared 404.17 for 360 d.o.f.). The event fluence (8-1000 keV) in this time interval is (1.25 +/- 0.24)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0-0.512 s in the 8-1000 keV band is 4.9 +/- 1.3 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."