梦飞巡天望远镜的正式巡天计划包括两部分：1）对北半球可观测天区开展多通道测光巡天（W巡天）；2）采用不同采样频率对多个不同面积的指定天区开展多通道测光巡天（D、H和M巡天）。

· W巡天：在正式巡天启动的第一年，用ugi、vrz两组滤光片对北半球可观测天区（δ>-15°，约27,000平方度）进行拍摄。曝光时间2×20秒，极限星等r≈22.37等。每个观测夜梦飞巡天望远镜将对同一天区进行两轮拍摄，时间间隔15-60分钟。全年预计完成两组滤光片各五组拍摄，叠加后极限星等达到r≈23.27等。经定标处理的真彩色图像将向全世界发布，供研究者使用。在随后的九年里，梦飞巡天望远镜还将用30%的时间观测W天区，平均每年完成三轮拍摄。正式巡天10年，完成两组滤光片总共18轮拍摄，最终极限星等r≈23.98等，颜色定标精度0.2-0.5%。

· D、H与M巡天：自正式巡天第二年起，梦飞巡天望远镜将用70%的观测时间对多个约1000平方度D天区、100平方度H天区及10平方度M天区进行ugi或vrz拍摄，采样频度分别为天、小时和分钟量级，开展时域天文学观测研究。D、H和M巡天将获取天体在不同时间跨度、不同采样间隔、不同采样次数、不同深度的高精度多波段亮度与实时颜色变化曲线。相比W巡天，D、H与M巡天采样频度更高、极限星等更深，为研究变源及暂现源提供极为丰富的高质量数据。

The Mephisto surveys will have two components: the Mephisto-W covering the whole northern sky of ～27,000 sq deg and the Mephisto-D, Mephisto-H, and Mephisto-M covering sky areas of respectively thousands, hundreds and tens of square degrees with a corresponding cadence of days, hours and minutes, targeting specifically fast variables and transients.

· Mephisto-W. The Mephisto-W survey will target the whole northern sky of ~27,000 sq deg at δ>-15°. The first year of the survey will be dedicated to Mephisto-W. The  entire survey area will be imaged five times over the year, in both ugi and vrz filter combinations, using pairs of 20-second exposures twice per night, delivering a typical 5σ depth of r~22.37 mag. For the following nine years, 30% of the observing time will be allocated to Mephisto-W. After 10 years of operation, Mephisto will uniformly observe the whole survey area 18 times (for both the ugi and vrz filter combinations), leading to a coadded depth of r~23.98 mag and colour accuracies of 0.2-0.5%.

· Mephisto-D, H, and M. Starting from the second year, 70% of the observing time will be allocated to Mephisto-D, H, and M surveys. Mephisto-D will cover several regions of interest, each of an area of ~1000 sq deg. Mephisto-H and Mephisto-M will target regions with higher sampling frequencies, with each D and M region covering an area of 100 sq deg, and 10 sq deg, respectively. The D, H, and M areas will be imaged in ugi or vrz filter combinations with the time intervals of days, hours, and minutes, respectively.  Compared to Mephisto-W, Mephisto-D, H and M will have better time samplings and deeper limiting magnitudes, providing high-quality data for time-domain science.

图1. 梦飞巡天望远镜不同类型巡天的面积和频次；Area and cadence for different surveys of Mephisto.