TITLE:   GCN CIRCULAR
NUMBER:  42449
SUBJECT: GRB 251025C: Fermi GBM Final Real-time Localization
DATE:    25/10/25 23:19:13 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 23:08:40 UT on 25 Oct 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251025C (trigger 783126525.293544 / 251025964).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 170.7, Dec = 54.9 (J2000 degrees, equivalent to J2000 11h 22m, 54d 53'), with a statistical uncertainty of 2.2 degrees.

The angle from the Fermi LAT boresight is 103.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251025964/quicklook/glg_skymap_all_bn251025964.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/bn251025964/quicklook/glg_healpix_all_bn251025964.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251025964/quicklook/glg_lc_medres34_bn251025964.gif