Program: GN-2022A-FT-213

The discovery of Active Galactic Nuclei (AGNs) that change their spectral type, i.e. the broad emission lines appear/disappear, challenges the traditional orientation based AGN unified model. Here we propose GMOS-N spectroscopic observations of 11 CLAGN candidates selected with a novel method that utilizes the variability features in light curves from the public available Zwicky Transient Facility. The light curves of type-I AGNs show stochastic variation that can be empirically described by the damped random walk (DRW) model, while those of type-II AGNs are flat and noise dominated. We fit each light curve and calculate the significance that it is consistent with a DRW model rather than noise. We search for candidates whose type inferred from the light curves are opposite to what was classified using the latest spectrum, and successfully obtain more than 50 candidates in total. Our initial test of spectroscopic follow-up using MDM 2.4m proves that this novel method can provide a much higher successful rate compared to traditional method. Some targets show repeat transition, which is extremely helpful to determine the timescale of CLAGNs. With a sample of confirmed CLAGNs, we will be able to study the typical dynamical range of Eddington ratios that lead to CLAGN phonmenon and the timescale of CLAGNs.