GCN Circular 23597
F. Dirirsa (U. Johannesburg) and M. Ohno (Hiroshima U.) report on behalf of the Fermi-LAT team: On December, 31, 2018 Fermi-LAT detected high-energy emission from GRB 181231A, which was also detected by Fermi-GBM (trigger 567919668 / 181231144). The best LAT on-ground location is found to be RA, Dec = 254.59, 0.61 (degrees, J2000) with an error radius of 0.24 deg (90 % containment, statistical error only). This was 51 deg from the LAT boresight at the time of the GBM trigger: T0 = 03:27:43.8 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 (7.8 degrees from the GBM location) with high significance. The photon flux above 100 MeV in the time interval 0-5000 s after the GBM trigger is 2.4 (+/-1.2)E-6 ph/cm2/s. The estimated photon index above 100 MeV is 2.21 (+/-0.37). A Swift ToO has been requested for this burst The Fermi-LAT point of contact for this burst is Feraol F. Dirirsa ( firstname.lastname@example.org). 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.