[vsnet-grb-info 19636] GRB 170728B: Fermi-LAT detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  21380
SUBJECT: GRB 170728B: Fermi-LAT detection
DATE:    17/07/29 13:03:36 GMT
FROM:    Manal Yassine at IN2P3/LUPM/CNRS  <manal.yassine at lupm.in2p3.fr>

M. Yassine (LUPM,CNRS,IN2P3) and J. L. Racusin (NASA/GSFC) report on 
behalf of the Fermi-LAT team:

On July 28, 2017, Fermi-LAT detected high-energy emission from GRB 170728B,
which triggered the Fermi-GBM (trigger 522975804) at 23:33:32 UT July, 
28 2017. This burst was also detected by Swift (Cenko et al., GCN Circ. 
21371).

The best LAT on-ground location is found to be

RA, Dec 238.97, 69.74 (degrees, J2000)

with an error radius of 0.53 deg (90% containment, statistical error only).
This was 30 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 is spatially and temporally correlated
with the GBM emission with high significance.
More than 10 photons above 100 MeV are observed within 100 seconds.
The highest-energy photon is a 0.6 GeV event which is
observed 9.3 seconds after the GBM trigger.

The Fermi-LAT point of contact for this burst is
Manal Yassine (manal.yassine at lupm.in2p3.fr).

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.