TITLE: GCN CIRCULAR NUMBER: 8801 SUBJECT: GRB 090108B: Fermi GBM detection DATE: 09/01/12 22:28:05 GMT FROM: Elisabetta Bissaldi at MPE E. Bissaldi (MPE) and A. von Kienlin (MPE) report on behalf of the Fermi GBM Team: "At 07:43:23.36 UT on 08 January 2009, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 090108B (trigger 253093405 / 090108322). The on-ground calculated location, using the GBM trigger data, is RA = 3.8, DEC = -32.2 (J2000 degrees, equivalent to 00h 15m, -32d 12'), with an uncertainty of 6.4 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 72 degrees. The GBM light curve shows a single spike with a duration (T90) of about 800 ms (8-1000 keV). The time-averaged spectrum from T0-0.295 s to T0+0.121 s is well fit by a simple power law function with index -0.99 +/- 0.06 (chi squared 246 for 242 d.o.f.). The event fluence (8-1000 keV) in this time interval is (7.9 +/- 0.4)E-07 erg/cm^2. The 32-ms peak photon flux measured starting from T0-0.008 s in the 8-1000 keV band is 19.0 +/- 1.3 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."