TITLE:   GCN CIRCULAR
NUMBER:  42202
SUBJECT: GRB 251011C: Fermi GBM Final Real-time Localization
DATE:    25/10/11 22:22:00 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 22:11:20 UT on 11 Oct 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251011C (trigger 781913485.841388 / 251011925).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 164.7, Dec = -2.9 (J2000 degrees, equivalent to J2000 10h 58m, -2d 53'), with a statistical uncertainty of 4.6 degrees.

The angle from the Fermi LAT boresight is 48.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251011925/quicklook/glg_skymap_all_bn251011925.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/bn251011925/quicklook/glg_healpix_all_bn251011925.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251011925/quicklook/glg_lc_medres34_bn251011925.gif