云南大学多通道测光巡天望远镜W巡天曝光时间优化  

On the Exposure Time of the Mephisto-W Survey

作　　者：雷磊 李晋达 吴金泰 蒋思艺 陈丙秋 Lei Lei;Li Jinda;Wu Jintai;Jiang Siyi;Chen Bingqiu(School of Physics and Astronomy,Yunnan University,Kunming 650500,China;South-Western Institute for Astronomy Research,Yunnan University,Kunming 650500,China)

机构地区：[1]云南大学物理与天文学院,云南昆明650500 [2]云南大学中国西南天文研究所,云南昆明650500

出　　处：《天文研究与技术》2021年第1期115-121,共7页Astronomical Research & Technology

基　　金：国家自然科学基金(11803029);国家级大学生创新训练项目(201910673001);云南大学科研经费(C176220100007)资助.

摘　　要：在建的云南大学多通道测光巡天望远镜(Multi-channel Photometric Survey Telescope,Mephisto)预计在2022年开展W巡天(Mephisto-W Survey),将对北半球可观测天区(赤纬δ>-15°,面积约26000平方度)开展多通道多历元测光巡天,为细致描绘银河系结构、深刻理解星系形成和演化理论、精确限制宇宙学模型、深入探究暗物质暗能量本质提供重大契机。基于丽江观测站天文台址监测系统2019全年观测数据,利用机器学习方法模拟丽江站一年的台址条件模型,简单估算了在不同曝光时间下,多通道多历元测光巡天一整年对巡天天区的可观测次数与期望极限星等。考虑到多通道多历元测光巡天的科学目标,建议对每个天区单次观测采用曝光2次,每次时长为20 s的曝光模式,在这种曝光模式下,可以实现全年对巡天天区在每组滤波片组合(ugi和vrz)下分别进行约3.8次观测,单次观测r波段极限星等可达22.37等,叠加星等可达23.11等。The multi-channel photometric survey telescope(Mephisto)that is under construction,is expected to carry out the Mephisto-W Survey in 2022.The Mephisto-W survey is a multi-channel and multi-epoch photometric survey that covers the observable northern sky(about 26000 sq.deg).The survey will provide an opportunity to describe the detailed structure of the Milky Way,to explore the formation and evolution history of galaxies,to accurately constrain the cosmology model,and to understand the nature of dark matter and dark energy.Based on the data from Astronomical Site Monitoring System(ASMS)in Lijiang Observatory during 2019,we have constructed models of the variations of values of seeing,cloud and sky brightness in Lijiang Observatory for a entire year by a machine learning method.Based on the models,we simply estimate the number of epochs and the expected limiting magnitudes of the Mephisto-W survey.To achieve the scientific goals of Mephisto-W survey,it is recommended to take the 2-time 20 s exposure mode.That is for each visit,we observe a given field twice,with each time of 20 s exposure time.In this mode,we are able to observe the survey about 3.8 times for both the ugi and vrz filter combinations.The expected 5 sigma r band depth of the single visit is 22.37 mag and co-added depth in one year 23.11 mag.

关 键 词：大天区巡天 台址条件 极限星等 

分 类 号：P141.2[天文地球—天体物理]