GCN Circular 42342
Subject
GRB 251018A: Fermi GBM Final Real-time Localization
Event
Date
2025-10-18T03:19:29Z (4 days ago)
From
Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>
Via
email
The Fermi GBM team reports the detection of a likely LONG GRB
At 03:12:00 UT on 18 Oct 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251018A (trigger 782449925.633958 / 251018133).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 294.7, Dec = -40.3 (J2000 degrees, equivalent to J2000 19h 38m, -40d 17'), with a statistical uncertainty of 6.8 degrees.
The angle from the Fermi LAT boresight is 36.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251018133/quicklook/glg_skymap_all_bn251018133.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/bn251018133/quicklook/glg_healpix_all_bn251018133.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251018133/quicklook/glg_lc_medres34_bn251018133.gif