TITLE: GCN CIRCULAR NUMBER: 43274 SUBJECT: GRB 251231A: Fermi GBM Final Real-time Localization DATE: 25/12/31 00:36:41 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 SHORT GRB At 00:25:42 UT on 31 Dec 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251231A (trigger 788833547.728264 / 251231018). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 312.1, Dec = -46.0 (J2000 degrees, equivalent to J2000 20h 48m, -46d 00'), with a statistical uncertainty of 16.4 degrees. The angle from the Fermi LAT boresight is 12.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251231018/q... The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251231018/q... The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251231018/q... View this GCN Circular online at https://gcn.nasa.gov/circulars/43274. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...