General information
EP260901a is a fast X-ray transient detected by Einstein Probe/WXT starting at 2026-09-01T05:07:45 UTC and lasting about 500 s. The reported position is RA 260.845 deg, Dec -19.232 deg with a 2.4 arcmin 90% uncertainty radius, and no known X-ray sources were reported inside the WXT error circle.
Wavelength coverage
- X-ray: EP-WXT detected the transient and measured an average unabsorbed 0.5-4 keV flux of 3.96e-10 erg cm^-2 s^-1 and peak flux about 3.7e-9 erg cm^-2 s^-1; EP-FXT observed about 17 hr later for 4 ks and found no significant source, with a 0.5-10 keV upper limit of about 1.0e-13 erg cm^-2 s^-1.
- Optical: MASTER-SAAO observed the field starting 53037 s after trigger and reported clear-band upper limits up to 17.8 mag.
No radio, gamma-ray, infrared, ultraviolet, neutrino, or gravitational-wave observations are mentioned.
Lightcurve and spectrum
- The WXT transient lasted about 500 s.
- The average WXT 0.5-4 keV spectrum was fit by an absorbed power-law model with fixed Galactic hydrogen column density NH = 3.34e21 cm^-2 and photon index 1.12 +/- 0.07.
- EP-FXT non-detection about 17 hr later implies the source had faded below about 1.0e-13 erg cm^-2 s^-1 in 0.5-10 keV.
- MASTER-SAAO obtained clear-band non-detections between about 53068 s and 53973 s after trigger, with limits from 17.4 to 17.8 mag.
Redshift
What’s special vs typical
The notable features are the short, bright soft X-ray flare, the absence of a known X-ray source in the WXT error circle, and the later X-ray non-detection by EP-FXT. However, the available circulars do not report a counterpart, host, redshift, or established classification.