GCN Circular 46118
Subject
GRB 261030B: Fermi GBM Final Real-time Localization
Event
Date
2026-10-30T21:54:00Z (2 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 21:43:27 UT on 30 Oct 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 261030B (trigger 815089412.659158 / 261030905).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 101.4, Dec = -52.8 (J2000 degrees, equivalent to J2000 06h 45m, -52d 47'), with a statistical uncertainty of 5.8 degrees.
The angle from the Fermi LAT boresight is 24.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn261030905/quicklook/glg_skymap_all_bn261030905.png
The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn261030905/quicklook/glg_healpix_all_bn261030905.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn261030905/quicklook/glg_lc_medres34_bn261030905.gif