//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17711 SUBJECT: GRB 150416A: Fermi-LAT detection DATE: 15/04/17 04:28:57 GMT FROM: Daniel Kocevski at GSFC D. Kocevski (NASA/Goddard) and E. Bissaldi (INFN Bari) report on behalf of the Fermi-LAT team: At 18:33:32 UT on April 15th, 2015, Fermi-LAT detected emission from GRB 150416A, which was also detected by Fermi-GBM (trigger 450902008/150416773). The GBM location was initially outside the LAT field of view at an angle of ~68 degrees to the LAT boresight. Therefore, no observations of events > 100 MeV are available during the emission observed by the GBM. Using the LAT Low Energy (LLE) data selection, over 25 counts above background were detected within a 50 s interval coinciding with the time of the GBM emission. This data selection has insufficient spatial resolution to provide a reliable LAT localization. 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: 17717 SUBJECT: GRB 150416A: Fermi GBM detection DATE: 15/04/17 18:32:07 GMT FROM: Peter Jenke at MSFC P. Jenke (UAH) reports on behalf of the Fermi GBM Team: "At 18:33:25.97 on April 16 2015, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 150416A (trigger 450902008/150416773) which was also detected by Fermi-LAT (D. Kocevski et al., GCN 17711) The GBM on-ground location, using the Fermi GBM trigger data, is RA = 58.8, Dec = 53.0 (J2000 degrees, equivalent to 3h 55m 00s, 53d 0’), with an uncertainty of 1.9 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 of the burst direction to the Fermi LAT boresight is 68 degrees. The GBM light curve consists of two peaks with a duration (T90) of about 33 s (50-300 keV). The time-averaged spectrum from T0+0s to T0+34.8s is well fit by a BAND function with Epeak = 940 +/- 160 keV, Alpha = -0.9 +/- 0.05 and Beta = -2.1 +/- 0.2. The event fluence (10-1000 keV) in this time interval is (1.4 +/- 0.04)E-05 erg/cm^2. The 1.0-sec peak photon flux measured starting from T0+12.8 s in the 10-1000 keV band is 3.8 +/- 0.2 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."