TITLE: GCN CIRCULAR NUMBER: 8497 SUBJECT: SGR 1806-20: Fermi GBM detection DATE: 08/11/07 17:26:47 GMT FROM: Sheila McBreen at MPE Sheila McBreen (UCD/MPE) and Chryssa Kouveliotou (NASA/MSFC) report on behalf of the Fermi GBM Team: "At 05:47:04.08 UT on 06 November 2008, the Fermi Gamma-Ray Burst Monitor triggered on a soft, short event (trigger 247643225 / 081106241). The on-ground calculated location, using the GBM trigger data, is RA = 271.3, DEC = -16.2 (J2000 degrees, equivalent to 18 h 05 m, -16 d 12 '), with an uncertainty of 5.6 degrees (radius, 1-sigma containment, statistical only; there is additionally a systematic error for soft localisations which is currently estimated to be 5 to 6 degrees). This position is consistent with SGR 1806-20. The angle from the Fermi LAT boresight is 41 degrees. The GBM light curve comprises a single peak with a duration of about 80 ms. The time-averaged spectrum from T0-0.045 s to T0+0.035 s is adequately fit by a simple power law function with index -2.13 +/- 0.08. (chi squared 205.1, for 242 d.o.f.) The event fluence (10-100 keV) in this time interval is (7.9 +/- 0.3)E-8 erg/cm^2. An optically thin thermal bremsstrahlung (OTTB) function fits the spectrum equally well (chi squared 203.9 for 242 d.o.f.) with kT = 36.5 +/-3.9 keV. The spectral analysis results presented above are preliminary, Final results will be published in the GBM Magnetar catalog."