LAMOST Spectroscopic Survey of the Galactic Anticentre (LSS-GAC): the second release of value-added catalogues

Maosheng Xiang, Xiaowei Liu, Haibo Yuan, Zhiying Huo, Yang Huang, Chun Wang, Bingqiu Chen, Juanjuan Ren, Huawei Zhang, Zhijia Tian, Yong Yang, Jianrong Shi, Jingkun Zhao, Ji Li, Yongheng Zhao, Xiangqun Cui, Guoping Li, Yonghui Hou, Yong Zhang, Wei Zhang, Jianling Wang, Yuzhong Wu, Zihuang Cao, Hongliang Yan, Taisheng Yan, Ali Luo, Haotong Zhang, Zongui Bai, Hailong Yuan, Yiqi Dong, Yajuan Lei, Guangwei Li

Published 2017-01-19Version 1

We present the second release of value-added catalogues of the LAMOST Spectroscopic Survey of the Galactic Anticentre (LSS-GAC DR2). The catalogues present values of radial velocity $V_{\rm r}$, atmospheric parameters --- effective temperature $T_{\rm eff}$, surface gravity log$g$, metallicity [Fe/H], $\alpha$-element to iron (metal) abundance ratio [$\alpha$/Fe] ([$\alpha$/M]), elemental abundances [C/H] and [N/H], and absolute magnitudes ${\rm M}_V$ and ${\rm M}_{K_{\rm s}}$ deduced from 1.8 million spectra of 1.4 million unique stars targeted by the LSS-GAC since September 2011 until June 2014. The catalogues also give values of interstellar reddening, distance and orbital parameters determined with a variety of techniques, as well as proper motions and multi-band photometry from the far-UV to the mid-IR collected from the literature and various surveys. Accuracies of radial velocities reach 5kms$^{-1}$ for late-type stars, and those of distance estimates range between 10 -- 30 per cent, depending on the spectral signal-to-noise ratios. Precisions of [Fe/H], [C/H] and [N/H] estimates reach 0.1dex, and those of [$\alpha$/Fe] and [$\alpha$/M] reach 0.05dex. The large number of stars, the contiguous sky coverage, the simple yet non-trivial target selection function and the robust estimates of stellar radial velocities and atmospheric parameters, distances and elemental abundances, make the catalogues a valuable data set to study the structure and evolution of the Galaxy, especially the solar-neighbourhood and the outer disk.