We present X-ray observations of the narrow line radio galaxy 1138 - 262 at z = 2.156 with the High Resolution Imager ( HRI ) on ROSAT .
Observations at other wave-bands , and in particular extremely high values of Faraday rotation of the polarized radio emission , suggest that the 1138 - 262 radio source is in a dense environment , perhaps a hot , cluster-type atmosphere .
We detect X-ray emission from the vicinity of 1138 - 262 , and we discuss possible origins for this emission .
The X-ray , optical , and radio data all favor thermal emission from a hot cluster atmosphere as the mechanism responsible for the X-rays , although we can not rule out a contribution from the active nucleus .
If this interpretation is correct , then 1138 - 262 becomes the most distant , by far , of known X-ray emitting clusters .
The X-ray luminosity for 1138 - 262 is 6.7 \pm 1.3 \times 10 ^ { 44 } ergs sec ^ { -1 } for emitted energies between 2 keV and 10 keV .

Subject headings : cosmology : large scale structure ; galaxies : clusters – active ; radio continuum – galaxies ; X-rays – galaxies