MEASUREMENT OF THE BROAD-LINE REGION SIZE IN 2 BRIGHT QUASARS

We present 4 years of spectrophotometric monitoring data for two radio -quiet quasars, PG 0804+762 and PG 0953+414, with typical sampling int ervals of several months. Both sources show continuum and emission-lin e variations. Tne variations of the H beta line follow those of the co ntinuum with a time lag, as derived from a cross-correlation analysis, of 93+/-30 days for PG 0804+762 and 111+/-55 days for PG 0953+414. Th is is the first reliable measurement of such a lag in active galactic nuclei with luminosity L > 10(45) ergs s(-1). The broad-line region (B LR) size that is implied is almost an order of magnitude larger than t hat measured in several Seyfert 1 galaxies and is consistent with the hypothesis that the BLR size grows as L(0.5).