General information
EP260610a is a fast X-ray transient detected by Einstein Probe WXT, with the corrected trigger time reported as 2026-06-10T04:49:21 UTC. EP-FXT follow-up detected an uncatalogued X-ray source at RA = 306.1022 deg, Dec = -25.9045 deg with a 10 arcsec radius uncertainty.
Wavelength coverage
- X-ray: EP-WXT detected the transient; refined analysis reports a WXT light curve lasting around 450 s, and EP-FXT detected an uncatalogued X-ray source in a roughly 3.5 ks follow-up.
- Optical: COLIBRÍ observed from 3.78 to 5.32 hours after trigger in r and z, with no detection to r > 24.0 mag and z > 22.6 mag; the refined EP circular also notes no optical counterpart in COLIBRÍ and SVOM/VT observations.
No radio, infrared, ultraviolet, gamma-ray, neutrino, or gravitational-wave observations are mentioned.
Lightcurve and spectrum
- WXT light curve lasted around 450 seconds before interruption of the autonomous follow-up.
- WXT 0.5-4 keV spectrum: absorbed power-law with fixed Galactic NH = 0.46 x 10^21 cm^-2, photon index 0.89 (+0.60/-0.57), and average unabsorbed flux 2.71 (+1.21/-0.70) x 10^-10 erg s^-1 cm^-2.
- FXT 0.5-10 keV spectrum: absorbed power-law with fixed Galactic NH = 0.46 x 10^21 cm^-2, photon index 1.95 (+0.07/-0.07), and average unabsorbed flux 0.82 (+0.06/-0.05) x 10^-11 erg s^-1 cm^-2.
- COLIBRÍ stacked imaging found no new source at the FXT position to 5-sigma limits of r > 24.0 mag and z > 22.6 mag.
Redshift
What’s special vs typical
The event is notable as a fast X-ray transient with an uncatalogued FXT counterpart and rapid X-ray follow-up, but no optical counterpart or redshift is reported in the provided circulars.