TITLE:   GCN CIRCULAR
NUMBER:  43795
SUBJECT: GRB 260221A: Fermi GBM Final Real-time Localization
DATE:    26/02/21 16:33:30 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 16:22:52 UT on 21 Feb 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260221B (trigger 793383777.240036 / 260221683).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 213.3, Dec = 51.9 (J2000 degrees, equivalent to J2000 14h 13m, 51d 53'), with a statistical uncertainty of 6.6 degrees.

The angle from the Fermi LAT boresight is 128.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260221683/quicklook/glg_skymap_all_bn260221683.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/bn260221683/quicklook/glg_healpix_all_bn260221683.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260221683/quicklook/glg_lc_medres34_bn260221683.gif