TITLE: GCN CIRCULAR NUMBER: 44673 SUBJECT: GRB 260519D: Fermi GBM Final Localization Correction DATE: 26/05/20 03:51:26 GMT FROM: Lorenzo Scotton at UAH The Fermi GBM team reports the detection of a likely LONG GRB "At 19:37:23.371 UT on 19 May 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260519D (trigger 800912248/260519818). This trigger was initially not classified as a GRB by the flight software, but is in fact a GRB. The on-ground calculated location, using the Fermi GBM trigger data, is RA = 87.37, Dec = -6.37 (J2000 degrees, equivalent to J2000 5h 49m, -6d 22’), with a statistical uncertainty of 14 degrees. The angle from the Fermi LAT boresight is 26 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260519818/quicklook/glg_skymap_all_bn260519818.png The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260519818/quicklook/glg_healpix_all_bn260519818.fit The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260519818/quicklook/glg_lc_medres34_bn260519818.gif"