GCN Circular 21452
Subject
GRB 170810A: Fermi-LAT detection
Event
Date
2017-08-11T02:24:00Z (8 years ago)
From
Judith Racusin at GSFC <judith.racusin@nasa.gov>
J. L. Racusin (NASA/GSFC), E. Burns (NASA/GSFC), D. Kocevski (NASA/MSFC), F. Longo (University
and INFN, Trieste), J. McEnery (NASA/GSFC), S. Razzaque (Johannesburg), G. Vianello (Stanford),
report on behalf of the Fermi-LAT team:
Fermi-LAT detected high-energy emission from GRB 170810A, which trigger Fermi-GBM (trigger
524095306 / 170810918) and Swift-BAT (Gibson et al, GCN 21450) at 22:01:41 on August, 10, 2017.
The best LAT on-ground location is found to be
RA, Dec = 187.5, 3.33 (J2000)
with an error radius of 0.53 deg (90 % containment, statistical error only), which is consistent with the
Swift BAT, XRT, and UVOT positions (Gibson et al, GCN 21450; Goad et al., GCN 21451), as well as
MASTER-NET (Rebolo et al, GCN 21449).
This was 60 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 2.3 GeV event which is observed 34 seconds after the GBM trigger.
The Fermi-LAT point of contact for this burst is Judith Racusin (judith.racusin@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.