TITLE:   GCN CIRCULAR
NUMBER:  45992
SUBJECT: GRB 261020A: Fermi GBM Final Real-time Localization
DATE:    26/10/20 05:47:46 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 05:37:08 UT on 20 Oct 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 261020A (trigger 814167433.941196 / 261020234).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 284.4, Dec = -33.9 (J2000 degrees, equivalent to J2000 18h 57m, -33d 53'), with a statistical uncertainty of 2.5 degrees.

The angle from the Fermi LAT boresight is 86.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn261020234/quicklook/glg_skymap_all_bn261020234.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/bn261020234/quicklook/glg_healpix_all_bn261020234.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn261020234/quicklook/glg_lc_medres34_bn261020234.gif