[vsnet-grb-info 16295] GRB 150314A: Fermi-LAT detection

[GCN Circulars]

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.  <magaxe at kth.se>

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 at astro.su.se<mailto:magnus.axelsson at 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.