TITLE:   GCN CIRCULAR
NUMBER:  42038
SUBJECT: GRB 251001B: Fermi GBM Final Real-time Localization
DATE:    25/10/01 14:28:02 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 14:17:19 UT on 1 Oct 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251001B (trigger 781021044.051374 / 251001595).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 52.0, Dec = -11.2 (J2000 degrees, equivalent to J2000 03h 28m, -11d 11'), with a statistical uncertainty of 5.6 degrees.

The angle from the Fermi LAT boresight is 67.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251001595/quicklook/glg_skymap_all_bn251001595.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/bn251001595/quicklook/glg_healpix_all_bn251001595.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251001595/quicklook/glg_lc_medres34_bn251001595.gif