TITLE: GCN CIRCULAR NUMBER: 39459 SUBJECT: GRB 250223C: Fermi GBM Final Real-time Localization DATE: 25/02/24 17:27:23 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 16:18:20 UT on 23 Feb 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250223C (trigger 762020305.175056 / 250223679).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 262.6, Dec = 41.0 (J2000 degrees, equivalent to J2000 17h 30m, 41d 00'), with a statistical uncertainty of 5.1 degrees.

The angle from the Fermi LAT boresight is 41.0 degrees.

The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250223679/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/bn250223679/q...

The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250223679/q...

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