TITLE:   GCN CIRCULAR
NUMBER:  44520
SUBJECT: GRB 260510C: Fermi GBM Final Real-time Localization
DATE:    26/05/10 17:24:27 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 17:13:43 UT on 10 May 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260510C (trigger 800126028.99095 / 260510718).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 174.6, Dec = 8.6 (J2000 degrees, equivalent to J2000 11h 38m, 8d 35'), with a statistical uncertainty of 10.4 degrees.

The angle from the Fermi LAT boresight is 66.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260510718/quicklook/glg_skymap_all_bn260510718.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/bn260510718/quicklook/glg_healpix_all_bn260510718.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260510718/quicklook/glg_lc_medres34_bn260510718.gif