GRB 260510B

General information

GRB 260510B triggered SVOM/ECLAIRs at 2026-05-10T12:19:20 UTC, with refined prompt analysis later reported and follow-up observations by multiple facilities. EP-FXT reported an uncatalogued fading X-ray source within the SVOM/ECLAIRs error circle.

Wavelength coverage

• Gamma-rays / hard X-rays: SVOM/ECLAIRs trigger and refined prompt properties; SVOM/GRM detection; Fermi-GBM targeted (sub-threshold) detection reported.
• X-rays (0.5–10 keV): EP-FXT follow-up detected an uncatalogued fading source with a power-law spectrum and reported flux.
• Optical: LCO, GOTO, and SVOM/VT reported only upper limits. No observations were mentioned in radio, infrared, ultraviolet, or TeV bands.

Lightcurve and spectrum

SVOM/ECLAIRs reported a multi-peaked prompt lightcurve with T90 = 12.05 (-3.49/+2.22) s (4–120 keV), and a time-averaged 5–120 keV spectrum fit by a power law with photon index -1.43 ± 0.12; the 4–120 keV fluence is (4.604 ± 0.481)×10^-7 erg/cm^2 and the 4–120 keV photon flux is 0.93 ± 0.09 ph/cm^2/s. EP-FXT reported an average 0.5–10 keV spectrum fit by an absorbed power law (NH fixed to Galactic) with photon index 2.24 (-0.56/+0.60) and an average unabsorbed 0.5–10 keV flux of 1.17 (-0.3/+1.7)×10^-12 erg s^-1 cm^-2.

Redshift

What’s special vs typical

An uncatalogued fading X-ray source was found by EP-FXT within the SVOM error circle while several rapid optical searches yielded only upper limits, suggesting an optically faint or obscured afterglow relative to typical bright optical counterparts.