TITLE: GCN CIRCULAR NUMBER: 38839 SUBJECT: GRB 250107B: Fermi GBM Final Real-time Localization DATE: 25/01/07 11:44:24 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 11:34:04 UT on 7 Jan 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250107B (trigger 757942449.293284 / 250107482).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 110.8, Dec = 59.6 (J2000 degrees, equivalent to J2000 07h 23m, 59d 36'), with a statistical uncertainty of 25.9 degrees.

The angle from the Fermi LAT boresight is 69.0 degrees.

The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250107482/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/bn250107482/q...

The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250107482/q...

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