GCN Circular 23767

F. Longo (University and INFN Trieste), E. Bissaldi (Politecnico & INFN Bari), M. Axelsson (KTH & Stockholm Univ.), M. Arimoto (Kanazawa Univ.), F. Piron (CNRS/IN2P3/LUPM) and N. Omodei (Stanford Univ.) report on behalf of the Fermi-LAT team:

On January, 22, 2019, Fermi-LAT detected high-energy emission from GRB 190122A, which was also detected by the Fermi GBM (trigger 569834352 / 190122305).

The best LAT on-ground location is found to be

RA, Dec =  258.71, 48.12 (degrees, J2000)

with an error radius of 0.91 deg (90% containment, statistical error only).

The LAT position was 26 deg from the LAT boresight at the time of the GBM trigger time (07:19:07.57 UT) and remained in the LAT field of view for ~1000 seconds, and then re-entered the FoV ~3800s after the trigger.

The data from the Fermi-LAT show a significant increase in the event rate above 100 MeV during the interval 0 4000s that is spatially correlated with the GBM trigger. The spectrum of the GRB appears to be soft, and the highest-energy photon is a 310 MeV event, which is observed ~820 seconds after the GBM trigger.

GRB190122A is also detected with high significance in the LAT Low Energy events (LLE), with a time profile which is temporally coincident with the GBM light curve.

Further analysis will be performed as more data become available.



The Fermi-LAT point of contact for this burst is Francesco Longo (francesco.longo@ts.infn.it<mailto:francesco.longo@ts.infn.it>).

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.