GRB 260117A

General information

GRB 260117A is a long, faint gamma-ray burst detected by SVOM/ECLAIRs at 2026-01-17 19:43:25 UTC (T0), with follow-up identifying a fading Swift-XRT source consistent with the afterglow and an optical counterpart consistent with fading.

Wavelength coverage

• Gamma-rays / hard X-rays: Detected by SVOM/ECLAIRs (5–20 keV imaging trigger) and SVOM/GRM.
• X-rays: Swift-XRT detected uncatalogued sources; Source 1 later showed >3σ fading and is likely the afterglow.
• Optical: Early upper limits from SVOM/C-GFT (g/i), detection by SVOM/VT (VT_R; VT_B limit), detection by SVOM/COLIBRÍ in r (with z-band limit), and a later R-band upper limit from ZTSh. No observations were mentioned in UV, near-IR (beyond z), mm/sub-mm, or radio.

Lightcurve and spectrum

Prompt emission: SVOM/GRM reports a double-peak structure with T90 ≈ 20 (−4/+5) s. X-rays: Swift-XRT Source 1 flux ≈ 3.90×10^-13 erg cm^-2 s^-1 (0.3–10 keV, observed) in early PC-mode data, and later the source faded with >3σ significance; a temporal decay index constraint of alpha > 0.2 was reported. Optical: SVOM/VT detected VT_R = 22.98 ± 0.25 AB at ~4.36 hr (VT_B > 23.8); SVOM/COLIBRÍ measured r = 24.27 ± 0.12 AB at 12–18 hr with z > 23.7 (3σ), consistent with fading; ZTSh reported R > 23.2 (3σ) at ~1.07 d.

Redshift

What’s special vs typical

The burst is described as long and faint, detected only by SVOM’s count-rate trigger (no immediate SVOM slew). Deep imaging suggests a faint pre-existing source at the afterglow position (r ~ 24.4), possibly the host galaxy.