Program: GN-2022B-Q-219

Black hole (BH) mass is the most fundamental parameter in understanding Active Galactic Nuclei (AGN) physics and BH-galaxy coevolution. AGN size-luminosity relation derived from reverberation mapping (RM) studies provides an extreme powerful tool for estimating BH mass. The current RM sample suffers from limited dynamical range of luminosity, that only a few AGNs with logL5100>45.0 have been studied. In addition, highly accreting AGNs are claimed to deviate from pre-calibrated size-luminosity relation. We propose GMOS spectroscopy monitoring for a sample of 12 uniquely selected quasars at logL5100~[45.0,46.0], whose expected lag in observe frame are close to 1 year. With the help of dense photometric light curves from ZTF and ATLAS, our strategy of selecting 1 year lag targets minimizes the affection of seasonal gap, and achieves a successful rate of >90% to recover their lags from simulation. In 2022B, we request repeated observations of nine targets with a desireble cadence is about a month. These new data will enable us to properly measure the lag and anchor the size-luminosity relation at high luminosity end. These results will provide crucial constraints on single epoch BH mass calibration especially for high-z quasars.