General information
GRB 251226A triggered multiple high-energy instruments on 2025-12-26 around 08:01:03 UTC, including GECAM-B and SVOM/GRM, with additional detections reported by HXMT and the ISS-based Glowbug telescope. A coarse sky localization was reported by GECAM-B near RA 260.2 deg, Dec 47.0 deg.
Wavelength coverage
- Gamma-rays / hard X-rays: detections by GECAM-B (70–6000 keV), SVOM/GRM (15–5000 keV), and Glowbug; HXMT is also reported as a detector.
No observations were mentioned in optical/UV, soft X-ray (imaging follow-up), infrared, radio, GeV/TeV, or neutrinos/GW.
Lightcurve and spectrum
- Timing: SVOM/GRM reports a precursor followed by main emission with T90 = 58.7 (+9.0/-9.4) s (15–5000 keV). GECAM-B reports T90 = 35.9 (+3.4/-6.0) s (70–6000 keV) with a precursor-like pulse and relatively short quiescent time before the main emission. Glowbug reports a single peak with duration 9.2 s and total significance ~15.9σ (adaptive 32 ms window).
- Spectrum (SVOM/GRM): time-averaged T0−3 to T0+100 s best fit by cutoff power law with index −1.29 (+0.22/−0.19) and Epeak = 632 (+279/−146) keV; fluence (10–1000 keV) = (4.33 ± ~0.20)×10^−5 erg cm^−2.
- Peak spectrum (SVOM/GRM): 1 s interval T0+3 to T0+4 s best fit by cutoff power law with index −1.18 (+0.27/−0.20) and Epeak = 1520 (+122/−56) keV; flux (10–1000 keV) = (2.61 ± 0.17)×10^−6 erg cm^−2 s^−1.
Redshift
What’s special vs typical
- A precursor-like pulse with a relatively short quiescent gap before the main emission is explicitly noted.
- Glowbug reports detection despite an unfavorable geometry/passive-material path on the ISS, with preliminary response-systematics caveats.