We describe the current plans for a spectroscopic survey of millions of stars in the Milky Way galaxy using the Guo Shou Jing Telescope （GSJT, formerly calledthe Large sky Area Multi-Object fiber Spectroscopic Telescope -- LAMOST）. The survey will obtain spectra for 2.5 million stars brighter than r 〈 19 during dark/grey time, and 5 million stars brighter than r 〈 17 or J 〈 16 on nights that are moonlit or have low transparency. The survey will begin in the fall of 2012, and will run for at least four years. The telescope＇s design constrains the optimal declination range for observations to 10~ 〈 di 〈 50~, and site conditions lead to an emphasis on stars in the direction of the Galactic anticenter. The survey is divided into three parts with different target selection strategies： disk, anticenter, and spheroid. The resulting dataset will be used to study the merger history of the Milky Way, the substructure and evolution of the disks, the nature of the first generation of stars through identification of the lowest metallicity stars, and star formation through study of open clusters and OB associations. Detailed design of the LAMOST Experiment for Galactic Understanding and Exploration （LEGUE） survey will be completed in summer 2012, after a review of the results of the pilot survey.
Li-Cai DengHeidi Jo NewbergChao LiuJeffrey L. CarlinTimothy C. BeersLi ChenHsu-Tai LeeCarl J. GrillmairPuragra Guhathakurta]Zhan-Wen HanJin-Liang HouSebastien LepineJing LiXiao-Wei LiuKai-Ke PanJ. A. SellwoodBo WangHong-Chi WangFan YangBrian YannyHao-Tong ZhangYue-Yang ZhangZheng ZhengZi Zhu
The weather at the Xinglong Observing Station, where the Guo Shou Jing Telescope （GSJT） is located, is strongly affected by the monsoon climate in north- east China. The LAMOST survey strategy is constrained by these weather patterns. We present statistics on observing hours from 2004 to 2007, and the sky brightness, seeing, and sky transparency from 1995 to 2011 at the site. We investigate effects of the site conditions on the survey plan. Operable hours each month show a strong cor- relation with season： on average there are eight operable hours per night available in December, but only one-two hours in July and August. The seeing and the sky trans- parency also vary with season. Although the seeing is worse in windy winters, and the atmospheric extinction is worse in the spring and summer, the site is adequate for the proposed scientific program of the LAMOST survey. With a Monte Carlo simulation using historical data on the site condition, we find that the available observation hours constrain the survey footprint from 22h to 16h in right ascension; the sky brightness allows LAMOST to obtain a limiting magnitude of V = 19.5 mag with S/N= 10.
Song YaoChao LiuHao-Tong ZhangLi-Cai DengHeidi Jo NewbergYue-Yang ZhangJing LiNian LiuXu ZhouJeffrey L. CarlinLi ChenNorbert ChristliebShuang GaoZhan-Wen HanJin-Liang HouHsu-Tai LeeXiao-Wei LiuKai-Ke PanHong-Chi WangYan XuFan Yang
