TITLE: GCN CIRCULAR NUMBER: 42179 SUBJECT: GRB 251009A: Fermi GBM Final Localization DATE: 25/10/10 00:04:26 GMT FROM: Matt Godwin msg0028@uah.edu

The Fermi GBM team reports the detection of a likely SHORT GRB

"At 15:58:56.61 UT on 09 October 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251009A (trigger 781718341/251009666).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 72.05, Dec = -25.84 (J2000 degrees, equivalent to J2000 4h 48m, -25d 50'), with a statistical uncertainty of 25.22 degrees.

The angle from the Fermi LAT boresight is 86 degrees.

The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251009666/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/bn251009666/q...

The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251009666/q..."

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