TITLE:   GCN CIRCULAR
NUMBER:  44917
SUBJECT: GRB 260611B: Fermi GBM Final Real-time Localization
DATE:    26/06/11 21:44:58 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 21:32:33 UT on 11 Jun 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260611B (trigger 802906358.618188 / 260611898).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 13.3, Dec = 22.6 (J2000 degrees, equivalent to J2000 00h 53m, 22d 36'), with a statistical uncertainty of 2.2 degrees.

The angle from the Fermi LAT boresight is 88.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260611898/quicklook/glg_skymap_all_bn260611898.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/bn260611898/quicklook/glg_healpix_all_bn260611898.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260611898/quicklook/glg_lc_medres34_bn260611898.gif