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astro-ph2000
Optical spectral variability of PG QSOs
D. Trevese, F. Vagnetti
In previous studies we have shown that the optical variability of quasars increases, on average, with redshift. We explained this dependance in terms of a hardening of the spectrum…
astro-ph2000
Spectral Variability of QSOs in the Optical Band
Dario Trevese, Fausto Vagnetti
A new analysis of the variability of the spectral slope of PG QSOs has been performed, on the basis of recent literature data in the B and R photometric bands. Preliminary results…