GRB 260104A

General information

GRB 260104A was detected by Swift-BAT at 2026-01-04 05:37:02 UTC and followed up by Swift-XRT, which found an uncatalogued X-ray source with an enhanced position near RA 337.3992 deg, Dec −21.2955 deg. Multiple teams reported optical follow-up observations, all resulting in non-detections to limiting magnitudes.

Wavelength coverage

• Gamma-rays: Swift-BAT trigger and refined temporal/spectral analysis reported.
• X-rays: Swift-XRT position refinement, light-curve decay and spectral fit reported.
• Optical/UV: Swift-UVOT reports no credible afterglow candidate in initial products; ground-based optical imaging reports upper limits (COLIBRÍ, MASTER, FTW). No observations were mentioned in the provided circulars for radio, infrared, or very-high-energy gamma-rays.

Lightcurve and spectrum

• BAT (15–350 keV): T90 = 13.26 ± 2.65 s; mask-weighted light curve shows two pulses.
• BAT time-averaged spectrum (T−10.09 to T+5.22 s): cutoff power law with photon index 0.32 ± 1.08 and Epeak = 42.5 ± 8.8 keV; 15–150 keV fluence = (3.5 ± 0.5)×10^-7 erg/cm^2; 1 s peak flux (15–150 keV) = 1.3 ± 0.2 ph/cm^2/s.
• XRT late-time light curve (from T0+5.1 ks): power-law decay with alpha = 1.22 (+0.26/−0.23).
• XRT PC-mode spectrum: absorbed power law with photon index 1.78 (+0.16/−0.10); total NH ~3.55 (+3.69/−0.15)×10^20 cm^-2, consistent with Galactic; predicted T+24h observed 0.3–10 keV flux ~1.7×10^-13 erg/cm^2/s if decay continues.

Redshift

What’s special vs typical