The file "searched_quasar_catalog" lists the properties of the quasars that were searched for MgII. Please see the paper for details on quasar sample selection. The columns in the quasar catalog are as follows. They were obtained from SDSS DR4. Column 1: J2000 RA-DEC name Column 2: mjd Column 3: plate Column 4: fiber Column 5: Right Ascension (J2000) Column 6: Declination (J2000) Column 7: z_emission Column 8: Error in z_emission Column 9: fiber u magnitude (from DR4 catalog) Column 10: fiber g magnitude (from DR4 catalog) Column 11: fiber r magnitude (from DR4 catalog) Column 12: fiber i magnitude (from DR4 catalog) Column 13: fiber z magnitude (from DR4 catalog) Column 14: Error in fiber u magnitude Column 15: Error in fiber g magnitude Column 16: Error in fiber r magnitude Column 17: Error in fiber i magnitude Column 18: Error in fiber z magnitude