TITLE: GCN CIRCULAR NUMBER: 44415 SUBJECT: GRB 260428A: Fermi GBM Final Real-time Localization DATE: 26/04/28 14:31:09 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov> The Fermi GBM team reports the detection of a likely LONG GRB At 14:20:35 UT on 28 Apr 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260428A (trigger 799078840.683444 / 260428598). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 277.0, Dec = 1.9 (J2000 degrees, equivalent to J2000 18h 27m, 1d 53'), with a statistical uncertainty of 2.1 degrees. The angle from the Fermi LAT boresight is 88.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260428598/q... The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260428598/q... The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260428598/q... View this GCN Circular online at https://gcn.nasa.gov/circulars/44415. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...