* Astronomy

Title: Eight new quasars discovered by LAMOST in one extragalactic field
Authors: Xue-Bing Wu, Zhendong Jia, Zhaoyu Chen, Wenwen Zuo, Yongheng Zhao, Ali Luo, Zhongrui Bai, Jianjun Chen, Haotong Zhang, Hongliang Yan, Juanjuan Ren, Shiwei Sun, Hong Wu, Yong Zhang, Yeping Li, Qishuai Lu, You Wang, Jijun Ni, Hai Wang, Xu Kong, Shiyin Shen
(Version v3)

We report the discovery of eight new quasars in one extragalactic field (five degree centred at RA=08 58 08.2, Dec=01°32'29.7'') with the LAMOST commissioning observations on December 18, 2009. These quasars, with i magnitudes from 16.44 to 19.34 and redshifts from 0.898 to 2.773, were not identified in the SDSS spectroscopic survey, though six of them with redshifts less than 2.5 were selected as quasar targets in SDSS. Except one source without near-IR Y-band data, seven of these eight new quasars meet a newly proposed quasar selection criterion involving both near-IR and optical colours. Two of them were found in the 'redshift desert' for quasars (z from 2.2 to 3), indicating that the new criterion is efficient for recovering the missing quasars with similar optical colours as stars. Although LAMOST met some problems during the commissioning observations, we were still able to identify other 38 known SDSS quasars in this field, with i magnitudes from 16.24 to 19.10 and redshifts from 0.297 to 4.512. Our identifications imply that a substantial fraction of quasars may be missing in the previous quasar surveys. The implication of our results to the future LAMOST quasar survey is discussed.

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