标题： LAMOST在单一河外天区发现八个新的类星体 显示英文标题

标题： Eight new quasars discovered by LAMOST in one extragalactic field

摘要： 我们报告在1个河外天区（以RA=$08^h58^m08.2^s$，Dec=$01^o32'29.7''$为中心，5度范围）中发现了8个新的类星体，这是在2009年12月18日LAMOST调试观测中发现的。 这些类星体的$i$星等从16.44到19.34，红移从0.898到2.773，其光学颜色与恒星非常相似，并未在SDSS光谱调查中被选中。 其中7个是通过一种新的涉及近红外和光学颜色的准则被选为类星体候选体。 其中2个位于类星体的“红移沙漠”（$z$从2.2到3），表明新的准则对于恢复具有与恒星类似光学颜色的缺失类星体是有效的。 尽管LAMOST在调试观测期间遇到了许多问题，包括光纤定位精度低和穹顶视宁度差，但我们仍然能够在这个天区中识别出其他38个已知的SDSS类星体，其$i$星等从16.24到19.10，红移从0.297到4.512。 我们的识别结果表明，之前类星体调查中可能有大量类星体被遗漏。 讨论了我们的结果对未来LAMOST类星体调查的影响。 显示英文摘要

摘要： We report the discovery of eight new quasars in one extragalactic field (five degree centered at RA=$08^h58^m08.2^s$, Dec=$01^o32'29.7''$) 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, have optical colors quite similar as stars and were not targeted in the SDSS spectroscopic survey. Seven of them were selected as quasar candidates by a newly proposed criterion involving both near-IR and optical colors. 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 colors as stars. Although LAMOST met many problems including the the low accuracy of fiber positioning and poor dom seeing condition 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.