General information
EP260628a is a fast X-ray transient detected by EP-WXT at R.A. 312.9884 deg, Dec. -34.3748 deg, with a 2.8 arcmin 90% uncertainty radius. The event began on 2026-06-28T17:08:08 UTC, lasted about 30 s, and no known X-ray sources were reported inside the WXT error circle.
Wavelength coverage
- X-ray: EP-WXT detected the transient in 0.5-4 keV; EP-FXT followed up 13.5 hours later in 0.5-10 keV and detected no significant source, giving an upper limit of about 3.7 x 10^-13 erg cm^-2 s^-1.
No observations are mentioned in gamma-ray, optical, infrared, ultraviolet, radio, neutrino, or gravitational-wave bands.
Lightcurve and spectrum
- Duration: about 30 s from the EP-WXT detection.
- Peak flux: approximately 7 x 10^-9 erg cm^-2 s^-1 in 0.5-4 keV.
- Average unabsorbed flux: 1.87(-0.54/+0.71) x 10^-9 erg cm^-2 s^-1 in 0.5-4 keV.
- Spectrum: absorbed power-law fit with fixed Galactic NH = 4.86 x 10^20 cm^-2 and photon index 0.67(-0.52/+0.52).
- Follow-up fading constraint: no EP-FXT detection 13.5 hours after the WXT trigger, with a 0.5-10 keV upper limit of about 3.7 x 10^-13 erg cm^-2 s^-1.
Redshift
What’s special vs typical
- The event is notable for being a short, bright soft-X-ray transient with no known X-ray source in the WXT error circle and no detectable X-ray counterpart 13.5 hours later.