Absolute magnitudes and Hubble plot for QSOs Purchased

From a sample of 570 QSOs with redshifts ranging from 0.2 to more than 3, the optically most luminous are selected and a plot of absolute magnitude versus redshift is obtained, the absolute magnitudes being calculated on the assumption that the QSOs are at the cosmological distances implied by their redshifts. This plot shows that for redshift Z > 1, absolute magnitudes of the brightest QSOs remain nearly constant. The log Z–apparent magnitude plot for the brightest QSOs is also obtained. The slope of the least-squares fit line is consistent with the expected value of 0.2.