TITLE: GCN CIRCULAR NUMBER: 40406 SUBJECT: GRB 250509A: Fermi GBM Final Real-time Localization DATE: 25/05/09 22:43:58 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 22:33:29 UT on 9 May 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250509A (trigger 768522814.285632 / 250509940). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 46.0, Dec = -35.3 (J2000 degrees, equivalent to J2000 03h 04m, -35d 17'), with a statistical uncertainty of 3.0 degrees. The angle from the Fermi LAT boresight is 89.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250509940/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/bn250509940/q... The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250509940/q... View this GCN Circular online at https://gcn.nasa.gov/circulars/40406. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...