TITLE: GCN CIRCULAR NUMBER: 17576 SUBJECT: GRB 150314A: Fermi-LAT detection DATE: 15/03/14 14:02:47 GMT FROM: Magnus Axelsson at Stockholm U. M. Axelsson (KTH Royal Institute of Technology, Sweden), D. Kocevski (NASA/GSFC) and J. Racusin (NASA/GSFC) report on behalf of the Fermi-LAT team: At 04:54:50.9 UT on March 14, 2015, Fermi-LAT detected high-energy emission from GRB 150314A, which was also detected by Fermi-GBM (trigger 448001693/150314205) and Swift (Hagen et al., GCN 17573), and a possible optical counterpart by KAIT (Zhang et al., GCN 17574). The best LAT on-ground location is found to be RA, Dec 125.40, 64.46 (J2000) with an error radius of 0.85 deg (90% containment, statistical error only) and consistent with the Swift/XRT location. This was ~40 deg from the LAT boresight at the time of the trigger and triggered an autonomous repoint of the spacecraft. The data from the Fermi-LAT show a significant increase in the event rate within 10 degrees of the Swift/XRT location after the trigger. More than 14 photons above 100 MeV are observed within 500 seconds. The highest-energy photon is a 670 MeV event which is observed 78 seconds after the GBM trigger. The Fermi-LAT point of contact for this burst is Magnus Axelsson (magnus.axelsson@astro.su.se). 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.