We have analyzed archival XMM- Newton and Chandra observations of the \gamma -ray radio-quiet pulsar J1826 - 1256 and its pulsar wind nebula .
The pulsar spectrum can be described by a power-law model with a photon index \Gamma \approx 1 .
We find that the nebular spectrum softens with increasing distance from the pulsar , implying synchrotron cooling .
The empirical interstellar absorption–distance relation gives a distance of \approx 3.5 kpc to J1826 - 1256 .
We also discuss the nebula geometry and association between the pulsar , the very high energy source HESS J1826 - 130 , the supernova remnant candidate G18.45 - 0.42 and the open star cluster Bica 3 .