[vsnet-grb-info 20786] GRB 180703B: Fermi-LAT detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22884
SUBJECT: GRB 180703B: Fermi-LAT detection
DATE:    18/07/04 02:35:47 GMT
FROM:    Judith Racusin at GSFC  <judith.racusin at nasa.gov>

J. L. Racusin (NASA/GSFC), M. Crnogorčević (UMD), A. Barker (George Washington), 
G. Vianello (Stanford),  M. Axelsson (KTH and Stockholm University) report on behalf 
of the Fermi-LAT team:

At 22:46:51.32 UTC on July 03, 2018 Fermi-LAT detected high-energy emission from 
GRB 180703B, which was also detected by Fermi-GBM (trigger 552350816 / 180703949).
The best LAT on-ground location is found to be

RA, Dec = 96.92, -29.88 (J2000)

with an error radius of 0.4 deg (90% containment, statistical error only). 

This was 30 deg from the LAT boresight at the time of the trigger.

The data from the Fermi-LAT show a significant increase in the event rate that is spatially 
and temporally correlated with the trigger with high significance. 

The highest-energy photon is a ~1 GeV event which is observed 35 seconds after the GBM 
trigger.

A Swift ToO has been requested for this burst. 

The Fermi-LAT point of contact for this burst is Judith Racusin (judith.racusin at nasa.gov).

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.