We use the Sloan Digital Sky Survey ( SDSS ) Quasar Data Release 12 ( DR12Q ) , containing nearly 300,000 AGNs , to calculate the monochromatic luminosities at 5100Å , 3000Å , and 1350Å , derived from the broad-band extinction-corrected SDSS magnitudes .
After matching them to their counterparts based on spectra and published in the SDSS Quasar Data Release 7 ( DR7Q ) , we find perfect correlations with minute mean offsets ( \sim 0.01 dex ) and dispersions of differences of 0.11 , 0.10 , 0.12 dex , respectively , across a 2.5 dex luminosity range .
We then estimate the active galactic nuclei ( AGNs ) black hole masses using the broad line region radius–luminosity relations and the FWHM of the MgII and CIV emission lines , to provide a catalog of 283,033 virial black hole mass estimates ( 132,451 for MgII , 213,071 for CIV , and 62,489 for both ) along with the bolometric luminosity and the Eddington ratio estimates for 0.1 < z < 5.5 and for roughly a quarter of the sky covered by SDSS .
The black hole mass estimates from MgII turned out to be closely matched to the ones from DR7Q with the dispersion of differences of 0.34 dex across a \sim 2 dex BH mass range .
We uncovered a bias in the derived CIV FWHMs from DR12Q as compared to DR7Q , that we correct empirically .
The CIV BH mass estimates should be used with caution because the CIV line is known to cause problems in the BH mass estimation from single-epoch spectra .
Finally , after the FWHM correction , the AGN black hole mass estimates from CIV closely match the DR7Q ones ( with the dispersion of 0.28 dex ) , and more importantly the MgII and CIV BH masses agree internally with the mean offset of 0.07 dex and the dispersion of 0.39 dex .