TITLE:   GCN CIRCULAR
NUMBER:  44699
SUBJECT: GRB 260523B: Fermi GBM Final Real-time Localization
DATE:    26/05/23 19:36:40 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 SHORT GRB

At 19:26:02 UT on 23 May 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260523B (trigger 801257167.544222 / 260523810).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 34.1, Dec = -63.1 (J2000 degrees, equivalent to J2000 02h 16m, -63d 06'), with a statistical uncertainty of 3.1 degrees.

The angle from the Fermi LAT boresight is 121.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260523810/quicklook/glg_skymap_all_bn260523810.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/bn260523810/quicklook/glg_healpix_all_bn260523810.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260523810/quicklook/glg_lc_medres34_bn260523810.gif