摘要
We report the discovery of eight new quasars in one extragalactic field （a five-degree field centered at RA=08^h58^m08.2^s, Dec=01°32′29.7″） with the Guoshoujing Telescope （LAMOST） commissioning observations made on 2009 December 18. 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 for one source without near-IR Y-band data, seven of these eight new quasars satisfy a newly proposed quasar selection 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 uncovering missing quasars with similar optical colors to stars. Although LAMOST encountered some problems during the commissioning observations, we were still able to identify 38 other 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 miss- ing in previous quasar surveys. The implication of our results to the future LAMOST quasar survey is discussed.
We report the discovery of eight new quasars in one extragalactic field （a five-degree field centered at RA=08^h58^m08.2^s, Dec=01°32′29.7″） with the Guoshoujing Telescope （LAMOST） commissioning observations made on 2009 December 18. 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 for one source without near-IR Y-band data, seven of these eight new quasars satisfy a newly proposed quasar selection 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 uncovering missing quasars with similar optical colors to stars. Although LAMOST encountered some problems during the commissioning observations, we were still able to identify 38 other 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 miss- ing in previous quasar surveys. The implication of our results to the future LAMOST quasar survey is discussed.
基金
supported by the National Natural Science Foundation of China (Grant No.10525313)
the National Key Basic Research Science Foundation of China (2007CB815405)
The Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST,now called the Guoshoujing Telescope) is a National Major Scientific Project built by the Chinese Academy of Sciences
