The double revolving fiber positioning technology employed in the Large Sky Area Multi-Object Fiber Spectroscopic Telescope(LAMOST)represents one of the most successful advancements in large-scale multiobjective spect...The double revolving fiber positioning technology employed in the Large Sky Area Multi-Object Fiber Spectroscopic Telescope(LAMOST)represents one of the most successful advancements in large-scale multiobjective spectroscopy.The precision of fiber positioning is crucial,as it directly impacts the observational efficiency of LAMOST.A critical component of the fiber positioning system is the closed-loop control system,which traditionally utilizes the light spot generated at fiber end.However,this study introduces a novel approach based on front-illuminated LAMOST focal plane image measurements.Unlike back-illumination,front-illumination does not necessitate internal lighting in the spectrograph,thus reducing light pollution and eliminating the need for additional photography.This method employs an artificial intelligence model to analyze images captured at the focal plane unit(FPU),using the image of the white ceramic head on the FPU as the data set for training,the model is capable of accurately measuring the fiber positions solely through front-illumination.Preliminary trials indicate that the measurement accuracy achieved using the frontillumination method is approximately 0."13.This level of precision meets the stringent fiber positioning accuracy requirement of LAMOST,set at 0."2.Furthermore,this novel approach demonstrates compatibility with LAMOST’s existing closed-loop fiber control system,offering potential for seamless integration and enhanced operational efficiency.展开更多
This work shows details of an evaluation of an observational system comprising a complementary metal-oxidesemiconductor detector, 60 cm telescope and filter complement. The system’s photometric precision and differen...This work shows details of an evaluation of an observational system comprising a complementary metal-oxidesemiconductor detector, 60 cm telescope and filter complement. The system’s photometric precision and differential photometric precision, and extinction coefficients were assessed through observations of Supersky flat fields, open clusters, standard stars and exoplanets. Photometry was precision achieved at the 0.02 mag level, with differential photometry of 0.004 mag precision. Extinction was found to agree with previous studies conducted at Xinglong Observatory. Ultimately, the results demonstrate this observing system is capable of precision scientific observations with a charge-coupled device across the optical wavelengths.展开更多
The Phased Array Feed(PAF)is considered as one of the next generation receivers for radio telescopes,which can significantly enlarge the instantaneous Field-of-View of large aperture single dish radio telescopes and e...The Phased Array Feed(PAF)is considered as one of the next generation receivers for radio telescopes,which can significantly enlarge the instantaneous Field-of-View of large aperture single dish radio telescopes and enable more flexible observing configurations.Study efforts on PAF development for radio telescopes have been made for more than two decades and have become more and more applicable.We report the development of an ambient-temperature 19 element L-band PAF system and the experimental results including its far field beam pattern and system temperature measurement,which achieve the expectations.Implementing the aperture array beam-forming method,we demonstrate a wide-field Galactic HI observations in the radio camera mode.The results indicate that this system might be applicable for strong Galactic transient detections.This system could be directly equipped to large telescopes like the Five-hundred-meter Aperture Spherical radio Telescope(FAST)and FAST array in the future.展开更多
To date,the Large Sky Area Multi-Object Fiber Spectroscopic Telescope(LAMOST)has been in operation for 12 yr.To improve the telescope's astronomical observation accuracy,the original open-loop fiber positioning sy...To date,the Large Sky Area Multi-Object Fiber Spectroscopic Telescope(LAMOST)has been in operation for 12 yr.To improve the telescope's astronomical observation accuracy,the original open-loop fiber positioning system of LAMOST is in urgent need of upgrading.The upgrade plan is to install several fiber view cameras(FVCs)around primary mirror B to build a closed-loop feedback control system.The FVCs are 20 m from the focal surface.To reduce a series of errors when the cameras detect the positions of the optical fibers,we designed fiducial fibers on the focal surface to be fiducial points for the cameras.Increasing the number of fiducial fibers can improve the detection accuracy of the FVC system,but it will also certainly reduce the number of fiber positioners that can be used for observation.Therefore,the focus of this paper is how to achieve the quantity and distribution that meet the requirements of system detection.In this paper,we introduce the necessity of using fiducial fibers,propose a method for selecting their number and present several methods for assessing the uniformity of their distribution.Finally,we implement particle swarm optimization to find the best distribution of fiducial fibers.展开更多
基金supported by NSFC under grant Nos.12073046 and 12261141689the project has been provided by the National Development and Reform Commission.
文摘The double revolving fiber positioning technology employed in the Large Sky Area Multi-Object Fiber Spectroscopic Telescope(LAMOST)represents one of the most successful advancements in large-scale multiobjective spectroscopy.The precision of fiber positioning is crucial,as it directly impacts the observational efficiency of LAMOST.A critical component of the fiber positioning system is the closed-loop control system,which traditionally utilizes the light spot generated at fiber end.However,this study introduces a novel approach based on front-illuminated LAMOST focal plane image measurements.Unlike back-illumination,front-illumination does not necessitate internal lighting in the spectrograph,thus reducing light pollution and eliminating the need for additional photography.This method employs an artificial intelligence model to analyze images captured at the focal plane unit(FPU),using the image of the white ceramic head on the FPU as the data set for training,the model is capable of accurately measuring the fiber positions solely through front-illumination.Preliminary trials indicate that the measurement accuracy achieved using the frontillumination method is approximately 0."13.This level of precision meets the stringent fiber positioning accuracy requirement of LAMOST,set at 0."2.Furthermore,this novel approach demonstrates compatibility with LAMOST’s existing closed-loop fiber control system,offering potential for seamless integration and enhanced operational efficiency.
文摘This work shows details of an evaluation of an observational system comprising a complementary metal-oxidesemiconductor detector, 60 cm telescope and filter complement. The system’s photometric precision and differential photometric precision, and extinction coefficients were assessed through observations of Supersky flat fields, open clusters, standard stars and exoplanets. Photometry was precision achieved at the 0.02 mag level, with differential photometry of 0.004 mag precision. Extinction was found to agree with previous studies conducted at Xinglong Observatory. Ultimately, the results demonstrate this observing system is capable of precision scientific observations with a charge-coupled device across the optical wavelengths.
基金supported by the National Key R&D Program of China under grant No.2018YFA0404703the Open Project Program of the Key Laboratory of FAST,NAOC,Chinese Academy of Sciences。
文摘The Phased Array Feed(PAF)is considered as one of the next generation receivers for radio telescopes,which can significantly enlarge the instantaneous Field-of-View of large aperture single dish radio telescopes and enable more flexible observing configurations.Study efforts on PAF development for radio telescopes have been made for more than two decades and have become more and more applicable.We report the development of an ambient-temperature 19 element L-band PAF system and the experimental results including its far field beam pattern and system temperature measurement,which achieve the expectations.Implementing the aperture array beam-forming method,we demonstrate a wide-field Galactic HI observations in the radio camera mode.The results indicate that this system might be applicable for strong Galactic transient detections.This system could be directly equipped to large telescopes like the Five-hundred-meter Aperture Spherical radio Telescope(FAST)and FAST array in the future.
基金Funding for the research was provided by Cui Xiangqun’s Academician StudioGuoshoujing Telescope(the Large Sky Area Multi-Object Fiber Spectroscopic Telescope,LAMOST)is a National Major Scientific Project built by the Chinese Academy of SciencesFunding for the project has been provided by the National Development and Reform Commission。
文摘To date,the Large Sky Area Multi-Object Fiber Spectroscopic Telescope(LAMOST)has been in operation for 12 yr.To improve the telescope's astronomical observation accuracy,the original open-loop fiber positioning system of LAMOST is in urgent need of upgrading.The upgrade plan is to install several fiber view cameras(FVCs)around primary mirror B to build a closed-loop feedback control system.The FVCs are 20 m from the focal surface.To reduce a series of errors when the cameras detect the positions of the optical fibers,we designed fiducial fibers on the focal surface to be fiducial points for the cameras.Increasing the number of fiducial fibers can improve the detection accuracy of the FVC system,but it will also certainly reduce the number of fiber positioners that can be used for observation.Therefore,the focus of this paper is how to achieve the quantity and distribution that meet the requirements of system detection.In this paper,we introduce the necessity of using fiducial fibers,propose a method for selecting their number and present several methods for assessing the uniformity of their distribution.Finally,we implement particle swarm optimization to find the best distribution of fiducial fibers.
