TITLE:   GCN CIRCULAR
NUMBER:  44973
SUBJECT: GRB 260618A: Fermi GBM Final Real-time Localization
DATE:    26/06/18 06:56:28 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 06:45:34 UT on 18 Jun 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260618A (trigger 803457939.281242 / 260618282).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 281.5, Dec = 21.1 (J2000 degrees, equivalent to J2000 18h 45m, 21d 06'), with a statistical uncertainty of 6.3 degrees.

The angle from the Fermi LAT boresight is 72.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260618282/quicklook/glg_skymap_all_bn260618282.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/bn260618282/quicklook/glg_healpix_all_bn260618282.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260618282/quicklook/glg_lc_medres34_bn260618282.gif