TITLE: GCN CIRCULAR NUMBER: 39503 SUBJECT: GRB 250226B: Fermi GBM Final Real-time Localization DATE: 25/02/26 22:40:51 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 22:30:23 UT on 26 Feb 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250226B (trigger 762301828.12293 / 250226938).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 284.4, Dec = -10.8 (J2000 degrees, equivalent to J2000 18h 57m, -10d 48'), with a statistical uncertainty of 1.9 degrees.

The angle from the Fermi LAT boresight is 71.0 degrees.

The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250226938/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/bn250226938/q...

The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250226938/q...

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