GCN Circular 19586
Subject
GRB 160625B: Fermi-LAT refined analysis
Date
2016-06-26T07:55:38Z (9 years ago)
From
Judith Racusin at GSFC <judith.racusin@nasa.gov>
F. Dirirsa (U. Johannesburg), G. Vianello (Stanford), J. Racusin (NASA/GSFC), and
M. Axelsson (KTH Stockholm) report on behalf of the Fermi-LAT team:
We report the on-ground localization and analysis of GRB 160625B, which triggered
the LAT onboard (Dirisa et al., GCN 19580). All times are relative to the initial GBM
trigger (Burns et al, GCN 19581).
The best LAT on-ground location is found to be:
RA, Dec = 308.56, 6.93 deg (J2000)
with an error radius of 0.06 deg (90 % containment, statistical error only). This is fully
compatible with the position of the afterglow detected by Swift/XRT (Melandri et al.,
GCN 19585).
This was 42 deg from the LAT boresight at the time of the GBM trigger and triggered
an autonomous repoint of the spacecraft.
More than 300 photons were detected above 100 MeV. The LAT emission became
detectable during the second bright pulse observed by GBM at ~T0+181 s. The
highest-energy photon is a 15 GeV event which is observed ~345 seconds after
the GBM trigger. The GRB was detectable by the LAT up to ~1 ks after the
trigger. Data are still being collected, and pointed mode observations are continuing
to maximize exposure to the GRB location.
The Fermi-LAT point of contact for this burst is Feraol Dirirsa (fdirirsa@uj.ac.za <mailto:fdirirsa@uj.ac.za>).
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.