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 (Hasinger et al., Paper I). We have obtained deep broad-band CCD images of the field and spectra of many optical objects near the positions of the X-ray sources. We define systematically the process leading to the optical identifications of the X-ray sources. For this purpose, we introduce five identification (ID) classes that characterize the process in each case. Among the 50 X-ray sources, we identify 39 AGNs, 3 groups of galaxies, 1 galaxy and 3 galactic stars. Four X-ray sources remain unidentified so far; two of these objects may have an unusually large ratio of X-ray to optical flux.
|Original language||English (US)|
|Number of pages||9|
|Journal||Astronomy and Astrophysics|
|State||Published - Jan 20 1998|
All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics
- Space and Planetary Science