TITLE: GCN CIRCULAR NUMBER: 9571 SUBJECT: GRB 090625: Fermi GBM detection DATE: 09/06/25 14:15:33 GMT FROM: Arne Rau at MPE Arne Rau (MPE) reports on behalf of the Fermi GBM Team: "At 05:37:00.21 UT on 25 June 2009, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 090625 (trigger 267601022 / 090625234). The on-ground calculated location, using the GBM trigger data, is RA = 20.3, DEC = -6.4 (J2000 degrees, equivalent to 01 h 21 m, -06 d 24'), with an uncertainty of 3.1 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 13 degrees. The GBM light curve shows multiple weak pulses with a duration (T90) of about 51 s (8-1000 keV). The time-averaged spectrum from T0-6.144 s to T0+12.288 s is well fit by a power law function with an exponential high energy cutoff. The power law index is -0.6 +/- 0.2 and the cutoff energy, parameterized as Epeak, is 198 +/- 36 keV (chi squared 551 for 579 d.o.f.). The event fluence (8-1000 keV) in this time interval is (8.8 +/- 1.2)E-07 erg/cm^2. The 4.096-sec peak photon flux measured starting from T0+4.096 s in the 8-1000 keV band is 0.50 +/- 0.02 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."