GCN Circular 30270
M. Axelsson (KTH & Stockholm Univ.), R. Pillera (Politecnico and INFN Bari) and F. Longo (University and INFN Trieste.) report on behalf of the Fermi-LAT Collaboration: Fermi-LAT has detected high-energy emission from GRB 210619B, which was also detected by Swift (GCN 30261), Global MASTER-net (GCN 30262), Ondrejov D50 (GCN 26263), GECAM (GCN 26264), iTelescope T18 (GCN 30265) and SARA-KP (GCN 30268). The best LAT on-ground location is found to be (RA, Dec) = 319.7, 33.9 (degrees, J2000) with an error radius of 0.13 deg (90% containment, statistical error only). This position is consistent with the XRT localization (GCN 30267). The location of the GRB was outside the LAT FoV at the time of the trigger (T0 = 23:59:25 UT on 2021-06-19) and came into view at T0+200 s. The data from the Fermi-LAT show a significant increase in the event rate that is spatially correlated with the Swift emission with high significance. The highest energy photon is a 8.3 GeV event detected ~410 s after the trigger. The photon flux above 100 MeV in the time interval 200-1000 s after the Swift trigger is (1.6 +/- 1.2) e-06 ph/cm2/s. The estimated photon index above 100 MeV is -1.5 +/- 0.3. The Fermi-LAT point of contact for this burst is Roberta Pillera (email@example.com). 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.