TITLE: GCN CIRCULAR NUMBER: 8495 SUBJECT: GRB 081105B: Fermi GBM detection DATE: 08/11/07 17:01:51 GMT FROM: Andreas von Kienlin at MPE Elisabetta Bissaldi (MPE) and A. von Kienlin (MPE) report on behalf of the Fermi GBM Team: "At 14:43:51.29 UT on 05 November 2008, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 081105B (trigger 247589032 / 081105614). The on-ground calculated location, using the GBM trigger data, is RA = 215.7 deg, Dec = 42.8 (J2000 degrees, equivalent to 14h 23m, 42d 48'), with an uncertainty of 12 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 87 degrees. This short GRB consists of a single peak with an estimated T90 (8-1000 keV) of 180 ms and T50 (8-1000 keV) of 64 ms. The spectral fit to this weak event is poorly constrained. A fit of the time-averaged spectrum from T0-0.067 s to T0-0.019 s by a simple power law function yields an index of -1.17 +/- 0.05 (chi squared 311 for 421 d.o.f.). The event fluence (8-1000 keV) in this time interval is (2.28 +/- 0.11)E-07 erg/cm^2. The photon flux on the 16 ms timescale measured starting from T0-0.067 s in the 8-1000 keV band is 20 +/- 3 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."