TITLE: GCN CIRCULAR NUMBER: 9497 SUBJECT: GRB 090606: Fermi GBM detection DATE: 09/06/08 15:17:29 GMT FROM: Elisabetta Bissaldi at MPE Elisabetta Bissaldi (MPE) reports on behalf of the Fermi GBM Team: "At 11:18:08.00 UT on 06 June 2009, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 090606 (trigger 265979890 / 090606471). The on-ground calculated location, using the GBM trigger data, is RA = 146.9, DEC = -70.5 (J2000 degrees, equivalent to 09h 48m, -70d 30'), with an uncertainty of 5.6 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 128 degrees. The GBM light curve shows a long, weak pulse with a duration (T90) of about 60 s (8-1000 keV). The time-averaged spectrum from T0-5.1 s to T0+12.3 s is adequately fit by a simple power law function with index -1.63 +/- 0.09 (chi squared 243 for 237 d.o.f.). The event fluence (8-1000 keV) in this time interval is (3.19 +/- 0.16)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+8 s in the 8-1000 keV band is 2.41 +/- 0.17 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."