TITLE: GCN CIRCULAR NUMBER: 14560 SUBJECT: GRB 130504B: Fermi GBM detection DATE: 13/05/04 19:49:10 GMT FROM: Andreas von Kienlin at MPE A. von Kienlin (MPE) reports on behalf of the Fermi GBM Team: "At 07:32:03.39 UT on 04 May 2013, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 130504B (trigger 389345526/ 130504314). The on-ground calculated location, using the GBM trigger data, is RA = 353.5, DEC = -5.6 (J2000 degrees, equivalent to 23 h 34 m, -05 d 34'), with an uncertainty of 1 degree (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 57 degrees. Moreover, this burst was bright enough to result in a Fermi spacecraft autonomous rapid repoint (ARR) maneuver. This burst was also independently detected by INTEGRAL SPI-ACS. The GBM light curve consists of a single spike with a duration (T90) of about 0.4 s (50-300 keV). The time-averaged spectrum from T0-0.064 s to T0+0.448 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.42 +/- 0.04 and the cutoff energy, parameterized as Epeak, is 1300 (+80/-70)keV. The event fluence (10-1000 keV) in this time interval is (6.01 +/- 0.14)E-06 erg/cm^2. The 0.064-sec peak photon flux measured starting from T0+0.32 s in the 10-1000 keV band is 40 +/- 2 ph/s/cm^2. A Band function fits the spectrum equally well with Epeak= 1300 +/-80 keV, alpha = -0.42 +/-0.04 and beta = -3.4 (+0.4/-0.9). The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."