TITLE: GCN CIRCULAR NUMBER: 40652 SUBJECT: GRB 250609A: Fermi GBM Final Real-time Localization DATE: 25/06/09 08:57:49 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 08:47:18 UT on 9 Jun 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250609A (trigger 771151643.61016 / 250609366).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 150.6, Dec = -8.4 (J2000 degrees, equivalent to J2000 10h 02m, -8d 24'), with a statistical uncertainty of 36.2 degrees.

The angle from the Fermi LAT boresight is 81.0 degrees.

The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250609366/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/bn250609366/q...

The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250609366/q...

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