TITLE: GCN CIRCULAR NUMBER: 43907 SUBJECT: GRB 260303B: Fermi GBM Final Real-time Localization DATE: 26/03/03 13:34:53 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 13:24:20 UT on 3 Mar 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260303B (trigger 794237065.456588 / 260303559). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 9.3, Dec = -26.7 (J2000 degrees, equivalent to J2000 00h 37m, -26d 41'), with a statistical uncertainty of 1.6 degrees. The angle from the Fermi LAT boresight is 67.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260303559/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/bn260303559/q... The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260303559/q... View this GCN Circular online at https://gcn.nasa.gov/circulars/43907. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...