XDQSO, written in IDL, calculates photometric quasar probabilities to mimick SDSS-III’s BOSS quasar target selection or photometric redshifts for quasars, whether in three redshift ranges (z < 2.2; 2.2 leq z leq 3.5; z > 3.5) or arbitrary redshift ranges.
Please see citation information here: http://www.sdss3.org/svn/repo/xdqso/tags/v0_6/doc/build/html/index.html#ack