SAGE巡天介绍Ⅰ--测光系统和数据处理  

Stellar Abundance and Galaxy Evolution Survey—— Photometric System and Data Reduction

作　　者：范舟 赵刚[1,2] 王炜 赵景昆[1] 郑捷[1,2] 谈克峰[1] 刘玉娟 何维 宋轶晗[1] 姜晓军[1,2] 马路[4] FAN Zhou;ZHAO Gang;WANG Wei;ZHAO Jing-kun;ZHENG Jie;TAN Ke-feng;LIU Yu-juan;HE Wei;SONG Yi-han;JIANG Xiao-jun;MA Lu(Key Laboratory for Optical Astronomy,National Astronomical Observatories,Chinese Academy ofSciences,Beijing 100012,China;School of Astronomy and Space Science,University of ChineseAcademy of Sciences,Beijing 100049,China;Chinese Academy of Sciences South America Centerfor Astronomy,China-Chile Joint Center for Astronomy,Camino El Observatorio #1515,Las Condes,Santiago 7550000,Chile;Xinjiang Astronomical Observatory,Chinese Academy of Sciences,Urumqi830011,China)

机构地区：[1]中国科学院光学天文重点实验室,国家天文台,北京100101 [2]中国科学院大学天文与空间科学学院,北京100049 [3]中国科学院南美天文中心中智联合天文中心,智利圣地亚哥7550000 [4]中国科学院新疆天文台,乌鲁木齐830011

出　　处：《天文学进展》2018年第2期101-121,共21页Progress In Astronomy

基　　金：国家自然科学基金(11390371,11373003);国家自然科学基金联合基金(U1631102); 973项目(2015CB857002)

摘　　要：SAGE(Stellar Abundance and Galactic Evolution)巡天采用一套对恒星大气参数敏感的独特测光系统,包括uSC,vSAGE,g,r,i,Hα_n,Hα_w和λ_(DDO51)(David Dunlap Observatory,DDO)共8个波段。该系统对恒星大气参数(有效温度T_(eff)、表面重力lg g和金属丰度[Fe/H])和星际消光的测量比传统的uvbyβ系统(Str?mgren-Crawford,SC)更敏感。由于g,r,i波段带宽较宽,因而观测效率较高,对恒星大气参数的测量精度和观测效率均超过uvbyβ系统和宽带测光系统。利用美国亚利桑那大学Steward天文台2.3 m Bok望远镜、新疆天文台南山1 m望远镜和乌兹别克斯坦MAO(Maidanak Astronomical Observatory)1 m望远镜已展开巡天观测。项目计划在约4年时间内完成所有的巡天观测,北天天区覆盖面积约12000(~?)~2,高精度测光(信噪比为100σ)深度约15 mag(V波段);5σ探测极限可深至约20 mag(V波段)。最终将探测约5×108颗恒星,并得出其恒星大气参数以及星际消光。该样本比之前的u,v,b,y,β测光巡天,如GCS(Geneva-Copenhagen Survey)巡天和HM(Hauck and Mermilliod 1998)巡天,扩展到更深的区域,即深度达到7～8 mag(V波段)。利用观测得到的大样本恒星测光星表,可以开展如下课题的研究:(1)得到银河系约5×10~8颗恒星大样本的金属丰度分布,并根据恒星演化模型得到其年龄分布;(2)预期搜寻到一批贫金属星候选体,并利用其他望远镜进行下一步观测;(3)结合高质量的uSC波段数据,预期可以找到一批白矮星;(4)结合其他星表,预期找到一批长周期变源以及移动天体;(5)结合uSC波段数据和其他星表,预期可以找到一批类星体。The SAGE（Stellar Abundance and Galactic Evolution） survey utilizes a special photometric system, which includes 8 bands in total, u_（SC）, v_（SAGE）, g, r, i, Hα_w, Hα_n and λ_（DDO51）.Compared to the uvbyβ system, the SAGE system is designed more sensitive to the stellar atmospheric parameters（i.e., effective temperature T_（eff）, surface gravity lg g and metallicity[Fe/H]） and interstellar extinction. The system is also more efficient in observations as the bandwidths of g, r, i bands are much wider than those of the uvbyβ system. Therefore, the accuracy of the stellar parameter measurement of the SAGE system could actually exceed that of the broadband photometry. Three telescopes（2.3-m Bok telescope of Steward Observatory of University of Arizona, Nanshan 1-m telescope of Xinjiang Astronomical Observatory and Maidanak Astronomical Observatory（MAO） 1-m telescope of Uzbekistan） are used and all the observations of the survey will be completed within about 4 years. The footprint is more than12 000（~？）~2 of the north sky and the magnitude coverage of the high precision photometry is about 15 mag（100σ） in V-band; the 5σ detection limit is about 20.0 mag in V-band. Finally in total about 0.5 billion stars will be detected, and the stellar atmospheric parameters as well as the interstellar extinction will be determined. The SAGE survey actually could extend about7～8 mag（V-band） fainter than the previous uvbyβ survey, e.g., the Geneva-Copenhagen Survey（GCS） and the HM survey.

关 键 词：测光系统 数据处理 流量定标 天测定标 银河系结构 

分 类 号：P145.2[天文地球—天体物理]