TITLE:   GCN CIRCULAR
NUMBER:  45028
SUBJECT: GRB 260623A: Fermi GBM Final Real-time Localization
DATE:    26/06/23 13:09:24 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 12:56:49 UT on 23 Jun 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260623A (trigger 803912214.021094 / 260623539).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 39.3, Dec = -10.4 (J2000 degrees, equivalent to J2000 02h 37m, -10d 24'), with a statistical uncertainty of 11.8 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/bn260623539/quicklook/glg_skymap_all_bn260623539.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/bn260623539/quicklook/glg_healpix_all_bn260623539.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260623539/quicklook/glg_lc_medres34_bn260623539.gif