TITLE: GCN CIRCULAR NUMBER: 14969 SUBJECT: GRB 130628A: Fermi GBM detection DATE: 13/07/03 11:40:30 GMT FROM: David Byrne at UCD D. Byrne (UCD), C. Meegan (UAH) and M. Burgess (UAH) report on behalf of the Fermi GBM Team: "At 12:44:02.12 UT on 28 June 2013, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 130628A (trigger 394116245/130628531) High peak flux from the GRB caused GBM to issue a repoint request that reoriented the satellite to place the GRB near the LAT boresight for 2.5 hours, subject to Earth limb contraints. The on-ground calculated location, using the GBM trigger data, is RA = 6.29, DEC = -5.07 (J2000 degrees, equivalent to 00 h 25m, -5 d 0'), with an uncertainty of 1.71 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 67 degrees. The GBM light curve consists of two pulses with a duration (T90) of about 22 s (50-300 keV). The time-averaged spectrum from T0-3.1 s to T0+25.6 s is well fit by a power law function with an exponential high-energy cutoff. The power law index is -1.51 +/- 0.04 and the cutoff energy, parameterized as Epeak, is 128 +/- 11 keV. The event fluence (10-1000 keV) in this time interval is (9.9 +/- 0.3)E-6 erg/cm^2. The 1-sec peak photon flux measured starting from T0+2.8 s in the 10-1000 keV band is 14.5 +/- 0.3 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog." -- David Byrne BSc. School of Physics, Science Center North, University College Dublin, Belfield, Dublin 4, Ireland.