GCN Circular 41897
Subject
GRB 250920B: Fermi GBM Final Real-time Localization
Event
Date
2025-09-20T08:56:46Z (5 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 08:46:26 UT on 20 Sep 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250920B (trigger 780050791.161292 / 250920366).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 190.8, Dec = 47.4 (J2000 degrees, equivalent to J2000 12h 43m, 47d 23'), with a statistical uncertainty of 2.4 degrees.
The angle from the Fermi LAT boresight is 56.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250920366/quicklook/glg_skymap_all_bn250920366.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/bn250920366/quicklook/glg_healpix_all_bn250920366.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250920366/quicklook/glg_lc_medres34_bn250920366.gif