耀变体是活动星系核中活动性最激烈的一个子类，目前已发现的耀变体超过3500个，其中绝大部分的红移低于2.0，经常观测的一些源的红移更是低于0.5。高红移耀变体处于宇宙演化早期，具有耀变体形成时的一些物理性质，也是研究早期宇宙的探针之一。截至到2019年初，关于高红移耀变体的研究论文不超过35篇，一般都是关于宽波段光谱能量分布和整体辐射模型的，尚未有较系统的光学波段的监测和研究结果发表。本项目拟利用国内外1米级及以上口径的光学望远镜，对一批红移高于2.0的耀变体的天内光变开展较为系统的多光学波段的监测，以揭示其天内光学光变的性质，包括时标、谱变化、波段间光变的相关性及可能的时延，以约束其中心黑洞质量、辐射区的位置、光变机制和辐射模型。

Blazars are those AGNs with the most violent activities. So far, more than 3500 blazars have been discovered, most of which are low-redshift objects. Those frequently observed blazars have redshifts even lower than 0.5. The high-redshift blazars are within the early stages of the universe and have some physical properties when they were just formed. They are also probes of the early universe. Less than 35 papers have been published on high-redshift blazars up to 2019 and most papers focus on the broad-band spectral energy distribution and the overall emission model. There is yet no published results of systematic monitoring of the intraday optical variability of high-redshift blazars. This project aims at systematic multi-band optical monitoring of the intraday variability of some blazars with z > 2 by using ~1m or larger telescopes. Then we can get the properties of their intraday optical variability, such as the timescale, spectral change, inter-band correlation and possible time lag. The results can be used to constrain the black hole mass, location of the emission region, variation mechnism, and emission model.