TITLE:   GCN CIRCULAR
NUMBER:  44698
SUBJECT: GRB 260523A: Fermi GBM Final Real-time Localization
DATE:    26/05/23 16:16:46 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 16:06:10 UT on 23 May 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260523A (trigger 801245175.681708 / 260523671).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 315.6, Dec = -6.8 (J2000 degrees, equivalent to J2000 21h 02m, -6d 47'), with a statistical uncertainty of 5.5 degrees.

The angle from the Fermi LAT boresight is 51.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260523671/quicklook/glg_skymap_all_bn260523671.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/bn260523671/quicklook/glg_healpix_all_bn260523671.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260523671/quicklook/glg_lc_medres34_bn260523671.gif