Redshifts of Chandra X‐ray sources. (a) Adaptively smoothed full‐band image of the Caltech area with the available redshifts superposed. Redshifts are given immediately below the corresponding X‐ray sources, and all redshifts are spectroscopic except for that of CXOHDFN J123651.7+621221 (marked at ﹩z=2.700﹩) where the redshift is photometric and uncertain (see Paper I). The redshift of the object marked at ﹩z=3.479﹩ was determined using both photometry and spectroscopy (see § 6). The two X‐ray sources with asterisks beneath them are stars (of type M4). The adaptive smoothing is at the 3 σ level using the code of Ebeling et al. (2001). (b) Redshift distribution of the 30 extragalactic Chandra sources with measured redshifts.