TITLE: GCN CIRCULAR NUMBER: 9507 SUBJECT: GRB 090610: Fermi GBM detection DATE: 09/06/12 16:27:36 GMT FROM: Adam Goldstein at Fermi-GBM/UAH A. Goldstein (UAH) reports on behalf of the Fermi GBM Team: "At 15:33:25.94 UT on 10 June 2009, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 090610 (trigger 266340807 / 090610648). The on-ground calculated location, using the GBM trigger data, is RA = 84.2, DEC = 35.4 (J2000 degrees, equivalent to 05h 37m, 35d 224'), with an uncertainty of 5.2 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 70 degrees. This burst was also independently detected by INTEGRAL SPI-ACS. The GBM light curve consists of one main pulse with a duration (T90) of about 6.5 s (8-1000 keV). The time-averaged spectrum from T0-3.1 s to T0+3.2 s is best fit by a simple power law function with index -1.30 +/- 0.03 (chi squared 621.1 for 606 d.o.f.). The event fluence (8-1000 keV) in this time interval is (7.32 +/- 0.24)E-07 erg/cm^2. The 1-sec peak photon flux measured starting from T0-0.51 s in the 8-1000 keV band is 0.94 +/- 0.09 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."