TITLE:   GCN CIRCULAR
NUMBER:  43808
SUBJECT: GRB 260223A: Fermi GBM Final Real-time Localization
DATE:    26/02/23 04:20:24 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 04:11:09 UT on 23 Feb 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260223A (trigger 793512674.810552 / 260223174).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 110.5, Dec = -29.4 (J2000 degrees, equivalent to J2000 07h 21m, -29d 23'), with a statistical uncertainty of 1.7 degrees.

The angle from the Fermi LAT boresight is 33.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260223174/quicklook/glg_skymap_all_bn260223174.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/bn260223174/quicklook/glg_healpix_all_bn260223174.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260223174/quicklook/glg_lc_medres34_bn260223174.gif