TITLE:   GCN CIRCULAR
NUMBER:  43069
SUBJECT: GRB 251211A: Fermi GBM Final Real-time Localization
DATE:    25/12/11 02:51:35 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 02:40:59 UT on 11 Dec 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251211A (trigger 787113664.18548 / 251211112).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 181.9, Dec = -32.3 (J2000 degrees, equivalent to J2000 12h 07m, -32d 17'), with a statistical uncertainty of 6.4 degrees.

The angle from the Fermi LAT boresight is 28.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251211112/quicklook/glg_skymap_all_bn251211112.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251211112/quicklook/glg_healpix_all_bn251211112.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251211112/quicklook/glg_lc_medres34_bn251211112.gif