EP260416a

General information

EP260416a is an Einstein Probe WXT-triggered X-ray transient (T0 reported as 2026-04-16 05:25:24 UTC) with an EP-FXT localized uncatalogued X-ray source and a detected optical counterpart consistent with the FXT position.

Wavelength coverage

• X-ray: EP-WXT detection with spectral fit and flux estimate; EP-FXT follow-up with spectral fit and reported lack of significant variability out to T0+6 ks.
• Optical: Multiple facilities detected and monitored the counterpart in g/r/i/z/R/B bands with early non-detections, later brightening, and multi-day fading; optical spectroscopy obtained with NOT/ALFOSC and VLT/FORS2.
• Near-IR: J-band non-detection reported. No observations were mentioned in gamma-rays, radio, millimeter/submillimeter, or UV.

Lightcurve and spectrum

Redshift

• z = 1.91 (optical absorption-line spectroscopy)
• Tentative Mg II absorption at z=1.909 reported first; later VLT spectrum shows multiple absorption lines at z=1.910 and stated to confirm the earlier result.

What’s special vs typical