The ROSAT Deep Survey II. Optical identification, photomettry and spectra of sources in the Lockman field

Maarten Schmidt, Guenther Hasinger, James Gunn +7

The ROSAT Deep Survey includes a complete sample of 50 X-ray sources with fluxes in the $0.5-2$ keV band larger than 5.5 $10^{-15}$ erg cm${}^{-2}$ s${}^{-1}$ in the Lockman field (H…