The double revolving fiber positioning technology is one of the key technologies for the success of the Large Sky Area Multi-Object Fiber Spectroscopic Telescope(LAMOST).The accuracy of fiber positioning will directly...The double revolving fiber positioning technology is one of the key technologies for the success of the Large Sky Area Multi-Object Fiber Spectroscopic Telescope(LAMOST).The accuracy of fiber positioning will directly affect the observation efficiency of LAMOST.To achieve higher fiber positioning accuracy,the original open-loop controlled fiber positioning system urgently needs to be upgraded into a closed-loop control system.The fiber detection is the most important part of the closed-loop controlled fiber positioning system.The back-illuminated detection method is usually used to detect the fiber position by directly detecting the light spot generated at the fiber end in the multi-fiber spectral surveys.In this paper,we introduce a new method to measure the fiber position based on the image of the front-illuminated LAMOST focal plane.The front-illuminated image does not require lighting devices inside the spectrograph,and it could reduce the instability and light pollution in the spectrograph end.Our method measures the fiber position by fitting the profile of the fiber pinhole with a 2D Gaussian function.A series of tests show that the relative position measurement precision of the front-illuminated method is about 012,and the method could have the same accuracy as the back-illuminated method once the system bias is calibrated by a simple radial correction function.The required fiber positioning accuracy of LAMOST is 04,and the new method satisfies the requirement of LAMOST fiber detection accuracy and could be used in the closed-loop fiber control system.展开更多
The Large Sky Area Multi-Object Fiber Spectroscopic Telescope(LAMOST),also known as the Guoshoujing Telescope,is a major national scientific facility for astronomical research located in Xinglong,China.Beginning with ...The Large Sky Area Multi-Object Fiber Spectroscopic Telescope(LAMOST),also known as the Guoshoujing Telescope,is a major national scientific facility for astronomical research located in Xinglong,China.Beginning with a pilot survey in 2011,LAMOST has been surveying the night sky for more than 10 years.The LAMOST survey covers various objects in the Universe,from normal stars to peculiar ones.展开更多
The effect of Blandford_Znajek process on the thermodynamical evolution of Kerr black holes in active galactic nuclei is discussed. It is demonstrated that a black hole does not evolve into an extreme Kerr state provi...The effect of Blandford_Znajek process on the thermodynamical evolution of Kerr black holes in active galactic nuclei is discussed. It is demonstrated that a black hole does not evolve into an extreme Kerr state provided anti_accretion process exists.展开更多
基金supported by the Maintenance and renovation project of Major Science and Technology foundational facility of the Chinese Academy of Sciences,DSS-WXGZ-2020-0009 and DSS-WXGZ-2021-0004the support of the National Key R&D Program of China(2019YFA0405000)+3 种基金NFSC 12090041,U1931207,U2031207 and U1931126the support of the National Natural Science for Youth Foundation of China(No.11603043)Guo Shou Jing Telescope(the Large sky Area Multi-Object fiber Spectroscopic Telescope,LAMOST)is a National Major Scientific Project built by the Chinese Academy of Sciences.Funding for the project has been provided by the National Development and Reform CommissionLAMOST is operated and managed by the National Astronomical Observatories,Chinese Academy of Sciences。
文摘The double revolving fiber positioning technology is one of the key technologies for the success of the Large Sky Area Multi-Object Fiber Spectroscopic Telescope(LAMOST).The accuracy of fiber positioning will directly affect the observation efficiency of LAMOST.To achieve higher fiber positioning accuracy,the original open-loop controlled fiber positioning system urgently needs to be upgraded into a closed-loop control system.The fiber detection is the most important part of the closed-loop controlled fiber positioning system.The back-illuminated detection method is usually used to detect the fiber position by directly detecting the light spot generated at the fiber end in the multi-fiber spectral surveys.In this paper,we introduce a new method to measure the fiber position based on the image of the front-illuminated LAMOST focal plane.The front-illuminated image does not require lighting devices inside the spectrograph,and it could reduce the instability and light pollution in the spectrograph end.Our method measures the fiber position by fitting the profile of the fiber pinhole with a 2D Gaussian function.A series of tests show that the relative position measurement precision of the front-illuminated method is about 012,and the method could have the same accuracy as the back-illuminated method once the system bias is calibrated by a simple radial correction function.The required fiber positioning accuracy of LAMOST is 04,and the new method satisfies the requirement of LAMOST fiber detection accuracy and could be used in the closed-loop fiber control system.
基金This work is supported by the the National Natural Science Foundation of China under grant nos.11988101,11973049,11933004,11890694,12090040,12090042,12090043,12090044,11833002,11833006,12022304,11835057,11973052,11633005,12173007,11933001,11703035,U2031203,and U1531244the National Key R&D Program of China under grant nos.2019YFA0405100,2019YFA0405500,2019YFA0405502,2019YFA0405503,2019YFA0405504,2016YFA0400804,and 2019YFA0405000+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences,grant nos.XDB34020205 and XDB41000000H.Yan,H.L.,S.W.,and Hailong Yuan acknowledge support from the Youth Innovation Promotion Association of the Chinese Academy of Sciences(nos.2019060,Y202017,2019057,and 2020060,respectively).
文摘The Large Sky Area Multi-Object Fiber Spectroscopic Telescope(LAMOST),also known as the Guoshoujing Telescope,is a major national scientific facility for astronomical research located in Xinglong,China.Beginning with a pilot survey in 2011,LAMOST has been surveying the night sky for more than 10 years.The LAMOST survey covers various objects in the Universe,from normal stars to peculiar ones.
文摘The effect of Blandford_Znajek process on the thermodynamical evolution of Kerr black holes in active galactic nuclei is discussed. It is demonstrated that a black hole does not evolve into an extreme Kerr state provided anti_accretion process exists.
