Spectroscopy of quasar binary candidates

Of our 27 new quasar pair observations, 10 are binary quasars, which doubles the number of known g<21 binaries with 3"<={Delta}{theta}<6" separations. Several of our observed binaries are wide-separation lens candidates that merit additional higher resolution spectroscopy, as well as deep imaging to search for lensing galaxies.

Our candidates are initially selected by UV excess (u-g<1), but are otherwise selected irrespective of the relative colors of the quasar pair, and we thus use them to suggest optimal color similarity and photometric redshift approaches for targeting binary quasars or projected quasar pairs. We find that a third or more of all binary quasars have quite dissimilar components on the basis of a typical color similarity criterion ({chi}^2^_color_<~20).