GRB 260105A

General information

GRB 260105A is a likely long gamma-ray burst detected by Fermi/GBM and SVOM/GRM, with contemporaneous Einstein Probe reports of the fast X-ray transient EP260105a and a refined EP/FXT position and decaying X-ray light curve. Multiple optical follow-up campaigns reported only upper limits within the EP/FXT region.

Wavelength coverage

• Gamma-ray: Fermi/GBM detection and localization; SVOM/GRM reports T90 and prompt spectral fit/fluence.
• X-ray: Einstein Probe WXT/FXT detections with refined position, spectra, and evidence for decay during early FXT observation.
• Optical: Multiple facilities (MASTER, LCO, SVOM/VT, FTW, GTC/HiPERCAM) report non-detections with limits reaching i > 25.5 AB at ~10 days. No observations were mentioned in: radio, infrared, ultraviolet (distinct from optical), or very-high-energy gamma-rays.

Lightcurve and spectrum

• Prompt duration: T90 = 69(+16/-12) s (15–5000 keV; SVOM/GRM).
• Prompt spectrum: power-law index -1.64 (+0.08/-0.07) for T0-7 to T0+83 s (SVOM/GRM).
• Prompt fluence: (1.85±0.20)e-5 erg/cm^2 (10–1000 keV; SVOM/GRM).
• X-ray WXT spectrum: absorbed power law with photon index 0.89(-0.65/+0.67) (0.5–4 keV); unabsorbed flux ~ (1.1±0.5)e-9 erg/s/cm^2 (EP/WXT).
• X-ray FXT spectrum: absorbed power law with photon index 2.07(-0.56/+0.58) (0.5–10 keV); unabsorbed flux ~4.2(-1.7/+2.1)e-13 erg/s/cm^2 (EP/FXT).
• Temporal behavior: significant decay reported during the initial FXT observation (EP/FXT).

Redshift

What’s special vs typical