TITLE:   GCN CIRCULAR
NUMBER:  46069
SUBJECT: GRB 261028A: Fermi GBM Final Localization
DATE:    26/10/28 20:29:29 GMT
FROM:    Angus Jameson <abj0023@uah.edu>

The Fermi GBM team reports the detection of a likely LONG GRB

"At 13:06:16.22 UT on 28 October 2026, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 261028A (trigger 814885581/261028546).
This trigger was initially classified as Below horizon by the flight software,
but is in fact a GRB.

The on-ground calculated location, using the Fermi GBM trigger data,
is RA = 61.09, Dec = -62.05 (J2000 degrees, equivalent to J2000 04h 04m 21.6s, -62d 03'),
with a statistical uncertainty of 11.52 degrees.

The angle from the Fermi LAT boresight is 52 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn261028546/quicklook/glg_skymap_all_bn261028546.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/bn261028546/quicklook/glg_healpix_all_bn261028546.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn261028546/quicklook/glg_lc_medres34_bn261028546.gif"