General information
EP260728a is a fast X-ray transient detected by Einstein Probe/WXT on 2026-07-28, with automatic FXT follow-up detecting an uncatalogued X-ray source inside the WXT error circle.
Wavelength coverage
- X-ray: EP-WXT detected a roughly 70 s transient and measured an absorbed power-law spectrum; EP-FXT followed up about 4 minutes after trigger and detected an uncatalogued X-ray source.
- Optical: COLIBRÍ/DDRAGO z-band imaging at 37.2 to 38.6 hours after trigger found no new source at the FXT position to z > 21.5 AB, 3 sigma.
Bands with no observations mentioned: gamma-ray, UV, infrared, radio, neutrino, gravitational-wave.
Lightcurve and spectrum
- WXT event started at T0=2026-07-28T16:45:19 UTC and lasted about 70 s before the observation was interrupted by autonomous follow-up.
- WXT 0.5-4 keV spectrum was fitted with an absorbed power law with hydrogen column density 3.1 (+2.0/-1.8) x 10^21 cm^-2 and photon index 1.63 (+0.77/-0.72).
- WXT average unabsorbed 0.5-4 keV flux was 4.2 (+1.6/-0.8) x 10^-9 erg/s/cm^2.
- FXT 0.5-10 keV spectrum was fitted with an absorbed power law with fixed Galactic hydrogen column density 1.2 x 10^21 cm^-2 and photon index 2.23 (-0.18/+0.18).
- FXT unabsorbed 0.5-10 keV flux was 1.22 (-0.12/+0.14) x 10^-12 erg cm^-2 s^-1.
Redshift
What’s special vs typical