General information
Fermi GBM detected and localized GRB 251221B at 2025-12-21 18:46:21 UT, reported as a likely long-duration gamma-ray burst. The on-ground position is RA 274.7 deg, Dec -21.4 deg (J2000) with a 7.2 deg statistical uncertainty.
Wavelength coverage
- Gamma-rays: Detection and localization reported by Fermi GBM.
No observations mentioned in X-rays, UV, optical/NIR, radio, or other messengers.
Lightcurve and spectrum
Redshift
What’s special vs typical