1997A&A...320..395W

We present new X-ray and optical data of six emission line galaxies detected as sources in the ROSAT all-sky survey, of which previous optical spectroscopy had resulted in ambiguous classifications. Our high S/N optical spectra show all targets to be AGN, with five narrow-line Sy 1 galaxies and one of type Sy 1.8. Three objects have permitted lines of FWHM ≲800km/s, only slightly broader than the forbidden lines. In all five narrow-line objects, the Fe II line complexes can be detected. The X-ray spectral properties of the sample, however, are consistent with a random AGN sample, and neither particularly soft X-ray spectral slopes, nor significantly enhanced variability can be seen. We briefly discuss the implications for the optical identification of current and future deep X-ray surveys.