[vsnet-grb-info 22384] GRB 190511A: Fermi-LAT detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  24483
SUBJECT: GRB 190511A: Fermi-LAT detection
DATE:    19/05/11 13:15:11 GMT
FROM:    Magnus Axelsson at Stockholm U.  <magaxe at kth.se>

M. Axelsson (KTH and Stockholm Univ.), F. Longo (Univ. and INFN Trieste), M. Arimoto (Kanazawa Univ.) and F. Dirirsa (Univ. of Johannesburg) report on behalf of the Fermi-LAT team:

On May 11, 2019, Fermi-LAT detected high-energy emission from GRB 190511A, which was also detected by Fermi-GBM (trigger 579251669 / 190511302; GCN 24482) and Swift (GCNs 24472 and 24481).

The best LAT on-ground location is found to be

RA, Dec 126.36, -20.25 (degrees, J2000)

with an error radius of 0.2 deg (90% containment, statistical error only).
This was 24 deg from the LAT boresight at the time of the GBM trigger:

T0 =  07:14:24.36 UT.

The data from the Fermi-LAT show a significant increase in the event rate after the GBM trigger that is spatially correlated with the GBM emission with high significance and consistent with the Swift location.

The photon flux above 100 MeV in the time interval 0-1400s after the GBM trigger is 3.6e-6 ph/cm2/s.

The estimated photon index above 100 MeV is -2.0 +/- 0.2.

The Fermi-LAT point of contact for this burst is Feraol Dirirsa (fdirirsa at uj.ac.za<mailto:fdirirsa at 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.