General information
EP260830a is a fast X-ray transient detected by Einstein Probe/WXT, starting at 2026-08-30T15:30:23 UTC and lasting about 500 s. The reported position is RA = 2.055 deg, Dec = 16.919 deg, with no known X-ray sources in the WXT error circle.
Wavelength coverage
- X-ray: EP-WXT detected the transient and measured an average 0.5-4 keV unabsorbed flux of 3.69 (-1.65/+2.93) x 10^-11 erg cm^-2 s^-1; EP-FXT later found no significant source with a 0.5-10 keV upper limit of about 8.8e-14 erg cm^-2 s^-1.
- Optical: MASTER-OAFA observed the field and reported clear-band upper limits of 18.5-18.6 mag.
No radio, infrared, ultraviolet, gamma-ray, neutrino, or gravitational-wave observations are mentioned.
Lightcurve and spectrum
- The WXT event lasted about 500 s.
- The WXT 0.5-4 keV spectrum is fitted by an absorbed power-law model with fixed Galactic hydrogen column density 4.21 x 10^20 cm^-2 and photon index 1.03 (-0.92/+1.02).
- EP-FXT observed about 50 hours after the WXT detection for 5 ks and detected no significant X-ray source.
Redshift
What’s special vs typical
- The event is notable as a fast X-ray transient with no known X-ray source in the WXT error circle and a later X-ray nondetection, but the circulars do not establish its physical nature.