General information
EP260214a is an Einstein Probe (EP) fast X-ray transient detected by EP/WXT on 2026-02-14, with an uncatalogued X-ray source identified by EP/FXT within minutes and later refined to a ~10" (90% CL) localization.
Wavelength coverage
- X-ray: EP/WXT trigger and EP/FXT follow-up detection with spectral fits and fluxes reported.
- Optical: Multiple facilities report nondetections with limits from
17 mag (clear) to r23–24 and z22; a faint source at r26 AB is detected at the candidate radio position at 11.3 days.
- Near-IR: VLT/HAWKI J-band nondetection to J~25 AB (3σ).
- Radio: VLA reports a possible 6 GHz counterpart with flux density ~60 µJy.
- Gamma-ray: Coincidence with GRB 260214A is mentioned (no gamma-ray measurements detailed in the provided circulars).
No observations were mentioned for UV, mm/sub-mm, TeV, neutrinos, or gravitational waves.
Lightcurve and spectrum
- WXT: event start T0=2026-02-14T20:37:00 UTC; duration ~60 s; absorbed power-law fit (fixed NH=4.6×10^20 cm^-2) with photon index 0.8 (-0.6/+0.7); unabsorbed 0.5–4 keV flux 9.7 (-0.3/+0.4)×10^-11 erg s^-1 cm^-2.
- FXT: observation at 2.5 min after T0; exposure ~3.3 ks; absorbed power-law fit (fixed NH=1.6×10^20 cm^-2) with photon index 2.3 (-0.3/+0.3); unabsorbed 0.5–10 keV flux 1.4 (-0.1/+0.2)×10^-11 erg s^-1 cm^-2.
Redshift
A photometric redshift z=0.18±0.15 (PRLS) is quoted for a nearby bright galaxy used to estimate a projected offset for the candidate radio counterpart.
What’s special vs typical
A possible radio counterpart inside the refined X-ray localization and a faint optical source at that radio position (interpreted as likely host light) are reported, with explicit chance-coincidence calculations (Pcc at the few percent to ~1% level) discussed in the circulars.