//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19379 SUBJECT: GRB 160503A: Fermi-LAT detection DATE: 16/05/04 03:08:19 GMT FROM: Nicola Omodei at Stanford U. N. Omodei, G. Vianello (Stanford), J. Racusin (GSFC), E. Bissaldi (INFN Bari) report on behalf of the Fermi-LAT team: The Fermi-LAT detected high-energy emission from GRB 160503A which triggered the Fermi-GBM at 13:36:32.01 on May, 03, 2016 (trigger 483975395 / 160503567). The best LAT on-ground location is found to be: RA, Dec = 0.54, -1.93 (degrees, J2000) with an error radius of 0.52 deg (90 % containment, statistical error only). This was 25 deg from the LAT boresight at the time of the trigger. The event is faint and soft, but detected over a long time scale (10 ks). No events at GeV energies and above have been observed. A Swift ToO has been requested for this burst. The Fermi-LAT point of contact for this burst is Elisabetta Bissaldi (elisabetta.bissaldi@ba.infn.it). The Fermi-LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19380 SUBJECT: GRB 160503A: Fermi GBM observation DATE: 16/05/04 12:34:06 GMT FROM: Kilian Toelge at MPE B. Mailyan (UAH) and K. Toelge (MPE) report on behalf of the Fermi GBM Team: "At 13:36:32.008 UT on 03 May 2016, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 160503A (trigger 483975396 / 160503567), which was also detected by the LAT (N. Omodei et al. 2016, GCN 19379) The GBM on-ground location is consistent with the LAT position. The angle from the Fermi LAT boresight at the GBM trigger time is 25 degrees. The GBM light curve consists of two peaks with a duration (T90) of about 59.4 s (50-300 keV). The time-averaged spectrum from T0-4.9 s to T0+28.9 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -1.28 +/- 0.14 and the cutoff energy, parameterized as Epeak, is 138.7 +/- 33.5 keV. The event fluence (10-1000 keV) in this time interval is (2.15 +/- 0.25)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0-0.58 s in the 8-1000 keV band is 2.5 +/- 0.2 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."