General information
EP260729a was detected by Einstein Probe WXT as an X-ray transient at 2026-07-29T17:04:47 UTC, with FXT follow-up finding an X-ray source at RA 357.5308 deg, Dec 26.9981 deg. Subsequent analysis associates the trigger with the M4.0V high proper motion star RX J2350.0+2659 and favors a stellar flare origin.
Wavelength coverage
- X-ray: EP-WXT detected the trigger and EP-FXT detected an uncatalogued X-ray source within the WXT error circle; refined WXT analysis gives an apec spectrum with kT = 2.78 keV and average unabsorbed 0.5-4 keV flux of 9.42 (-3.00/+7.95)×10^-11 erg/s/cm^2.
- Optical: Ondrejov D50 obtained 19x120 s r'-band exposures starting about 4.1 h after trigger, found no uncatalogued object to r>21.5, and measured RX J2350.0+2659 as bright and fading.
No radio, infrared, ultraviolet, gamma-ray, gravitational-wave, or neutrino observations are mentioned.
Lightcurve and spectrum
- RX J2350.0+2659 appeared elevated in brightness at the start of the Ondrejov sequence and faded over about 40 minutes.
- A linear fit gave an initial optical excess of about 0.14 mag over the catalogued magnitude, decaying at about 0.1 mag/hour.
- The WXT 0.5-4 keV spectrum can be fitted with an apec model with best-fit temperature 2.78 keV.
- The derived average unabsorbed 0.5-4 keV flux is 9.42 (-3.00/+7.95)×10^-11 erg/s/cm^2, corresponding to luminosity 1.24 (-0.45/+1.03)×10^31 erg/s.
Redshift
What’s special vs typical