TITLE: GCN CIRCULAR NUMBER: 16081 SUBJECT: GRB 140406A: Fermi GBM observation DATE: 14/04/06 14:14:15 GMT FROM: Hoi-Fung Yu at MPE Subject: GRB 140406A: Fermi GBM observation Hoi-Fung Yu (MPE) reports on behalf of the Fermi GBM Team: "At 03:26:48.19 UT on 06 April 2014, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 140406A (trigger 418447611 / 140406144). This burst, tentatively classified as Unreliable Location by the FSW, is in fact due to Gamma-Ray Burst. The on-ground calculated location, using the GBM trigger data, is RA = 70.1, Dec = 13.5 (J2000 degrees, equivalent to 04h 40m, 13d 30'), with an uncertainty of 6 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 58 degrees. The GBM light curve consists of several pulses with a duration (T90) of about 42 s (50-300 keV). The time-averaged spectrum from T0-4.096 s to T0+36.864 s is well fit by a power law function with an exponential high-energy cutoff. The power law index is -0.3 +/- 0.2 and the cutoff energy, parameterized as Epeak, is 138 +/- 13 keV. The event fluence (10-1000 keV) in this time interval is (2.8 +/- 0.2)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+30.8 s in the 10-1000 keV band is 1.5 +/- 0.2 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."