TITLE: GCN CIRCULAR NUMBER: 9509 SUBJECT: GRB 090610C: Fermi GBM detection DATE: 09/06/12 16:29:53 GMT FROM: Adam Goldstein at Fermi-GBM/UAH A. Goldstein (UAH) reports on behalf of the Fermi GBM Team: "At 21:12:07.73 UT on 10 June 2009, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 090610C (trigger 266361129 / 090610883). The on-ground calculated location, using the GBM trigger data, is RA = 70.4, DEC = +30.3 (J2000 degrees, equivalent to 04h 42m, 30d 18'), with an uncertainty of 8.2 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 104 degrees. The GBM light curve consists of a single pulse with a duration (T90) of about 18.1 s (8-1000 keV). The time-averaged spectrum from T0-4.1 s to T0+8.2 s is best fit by a simple power law function with index -1.62 +/- 0.08 (chi squared 341.6 for 362 d.o.f.). The event fluence (8-1000 keV) in this time interval is (8.54 +/- 0.38)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 1.12 +/- 0.11 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."