TITLE: GCN CIRCULAR NUMBER: 39141 SUBJECT: GRB 250204B: Fermi GBM Final Localization DATE: 25/02/04 14:58:59 GMT FROM: Marianna Dafčíková at Masaryk University 500025@mail.muni.cz

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

At 06:41:14.00 UT on 04 February 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250204B (trigger 760344078/250204279).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 2.35, Dec = 29.70 (J2000 degrees, equivalent to J2000 0h 9m, +29d 41'), with a statistical uncertainty of 2.80 degrees.

The angle from the Fermi LAT boresight is 124 degrees.

The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250204279/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/bn250204279/q...

The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250204279/q...

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