TITLE:   GCN CIRCULAR
NUMBER:  44542
SUBJECT: GRB 260511B: Fermi GBM Final Real-time Localization
DATE:    26/05/11 11:10:56 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 11:00:31 UT on 11 May 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260511B (trigger 800190036.70394 / 260511459).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 192.2, Dec = 5.0 (J2000 degrees, equivalent to J2000 12h 48m, 5d 00'), with a statistical uncertainty of 1.4 degrees.

The angle from the Fermi LAT boresight is 101.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260511459/quicklook/glg_skymap_all_bn260511459.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/bn260511459/quicklook/glg_healpix_all_bn260511459.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260511459/quicklook/glg_lc_medres34_bn260511459.gif