Time-domain astronomy is one of the most important areas.Large sky area,deep-field,and short timescale are the priority of time-domain observations.SiTian is an ambitious ground-based project processing all sky optica...Time-domain astronomy is one of the most important areas.Large sky area,deep-field,and short timescale are the priority of time-domain observations.SiTian is an ambitious ground-based project processing all sky optical monitoring,aiming for a sky-survey timescale of less than 1 day.It is developed by the Chinese Academy of Sciences,an integrated network of dozens of 1 m class telescopes deployed worldwide.The Mini-SiTian Telescope Array is being carried out for demonstrations on optical design,group scheduling,and software pipeline developments,to overcome the high technical and financial difficulties of the SiTian project.One array contains three 300 mm F/3 telescopes,with an FOV of 5°over the 400–1000 nm wavelength range.The Mini-SiTian Telescope Array is now under commissioning in Xinglong Observatory,and a perfect platform for technical research and educational purposes.展开更多
The Large Sky Area Multi-Object Fiber Spectroscopic Telescope(LAMOST)has been in normal operation for more than 10 yr,and routine maintenance is performed on the fiber positioner every summer.The positioning accuracy ...The Large Sky Area Multi-Object Fiber Spectroscopic Telescope(LAMOST)has been in normal operation for more than 10 yr,and routine maintenance is performed on the fiber positioner every summer.The positioning accuracy of the fiber positioner directly affects the observation performance of LAMOST,and incorrect fiber positioner positioning accuracy will not only increase the interference probability of adjacent fiber positioners but also reduces the observation efficiency of LAMOST.At present,during the manual maintenance process of the positioner,the fault cause of the positioner is determined and analyzed when the positioning accuracy does not meet the preset requirements.This causes maintenance to take a long time,and the efficiency is low.To quickly locate the fault cause of the positioner,the repeated positioning accuracy and open-loop calibration curve data of each positioner are obtained in this paper through the photographic measurement method.Based on a systematic analysis of the operational characteristics of the faulty positioner,the fault causes are classified.After training a deep learning model based on long short-term memory,the positioner fault causes can be quickly located to effectively improve the efficiency of positioner fault cause analysis.The relevant data can also provide valuable information for annual routine maintenance methods and positioner designs in the future.The method of using a deep learning model to analyze positioner operation failures introduced in this paper is also of general significance for the maintenance and design optimization of fiber positioners using a similar double-turn gear transmission system.展开更多
Accurate flux density calibration is essential for precise analysis and interpretation of observations across different observation modes and instruments.In this research,we first introduce the flux calibration model ...Accurate flux density calibration is essential for precise analysis and interpretation of observations across different observation modes and instruments.In this research,we first introduce the flux calibration model that incorporated in Hi FAST pipeline,and designed for processing HⅠ21 cm spectra.Furthermore,we investigate different calibration techniques and assess the dependence of the gain parameter on the time and environmental factors.A comparison is carried out in various observation modes(e.g.,tracking and scanning modes)to determine the flux density gain(G),revealing insignificant discrepancies in G among different methods.Long-term monitoring data shows a linear correlation between G and atmospheric temperature.After subtracting the G-Temperature dependence,the dispersion of G is reduced to<3%over a one-year timescale.The stability of the receiver response of Five-hundred-meter Aperture Spherical radio Telescope(FAST)is considered sufficient to facilitate HⅠobservations that can accommodate a moderate error in flux calibration(e.g.,>~5%)when utilizing a constant G for calibration purposes.Our study will serve as a useful addition to the results provided by Jiang et al.Detailed measurement of G for the 19 beams of FAST,covering the frequency range 1000-1500 MHz,can be found on the Hi FAST homepage:https://hifast.readthedocs.io/fluxgain.展开更多
基金supported from the Strategic Pioneer Program of the Astronomy Large-Scale Scientific Facility,Chinese Academy of Sciences and the Science and Education Integration Funding of University of Chinese Academy of Sciencessupported by the National Key Basic R&D Program of China via 2023YFA1608304。
文摘Time-domain astronomy is one of the most important areas.Large sky area,deep-field,and short timescale are the priority of time-domain observations.SiTian is an ambitious ground-based project processing all sky optical monitoring,aiming for a sky-survey timescale of less than 1 day.It is developed by the Chinese Academy of Sciences,an integrated network of dozens of 1 m class telescopes deployed worldwide.The Mini-SiTian Telescope Array is being carried out for demonstrations on optical design,group scheduling,and software pipeline developments,to overcome the high technical and financial difficulties of the SiTian project.One array contains three 300 mm F/3 telescopes,with an FOV of 5°over the 400–1000 nm wavelength range.The Mini-SiTian Telescope Array is now under commissioning in Xinglong Observatory,and a perfect platform for technical research and educational purposes.
基金Funding for the research was provided by Cui Xiangqun’s Academician StudioFunding for the project has been provided by the National Development and Reform Commission。
文摘The Large Sky Area Multi-Object Fiber Spectroscopic Telescope(LAMOST)has been in normal operation for more than 10 yr,and routine maintenance is performed on the fiber positioner every summer.The positioning accuracy of the fiber positioner directly affects the observation performance of LAMOST,and incorrect fiber positioner positioning accuracy will not only increase the interference probability of adjacent fiber positioners but also reduces the observation efficiency of LAMOST.At present,during the manual maintenance process of the positioner,the fault cause of the positioner is determined and analyzed when the positioning accuracy does not meet the preset requirements.This causes maintenance to take a long time,and the efficiency is low.To quickly locate the fault cause of the positioner,the repeated positioning accuracy and open-loop calibration curve data of each positioner are obtained in this paper through the photographic measurement method.Based on a systematic analysis of the operational characteristics of the faulty positioner,the fault causes are classified.After training a deep learning model based on long short-term memory,the positioner fault causes can be quickly located to effectively improve the efficiency of positioner fault cause analysis.The relevant data can also provide valuable information for annual routine maintenance methods and positioner designs in the future.The method of using a deep learning model to analyze positioner operation failures introduced in this paper is also of general significance for the maintenance and design optimization of fiber positioners using a similar double-turn gear transmission system.
基金the support of the China National Key Program for Science and Technology Research and Development of China(2022YFA1602901,2023YFA1608204)the National Natural Science Foundation of China(Nos.11988101,11873051,12125302,12373011,12041305,12173016)the CAS Project for Young Scientists in Basic Research grant(No.YSBR-062)。
文摘Accurate flux density calibration is essential for precise analysis and interpretation of observations across different observation modes and instruments.In this research,we first introduce the flux calibration model that incorporated in Hi FAST pipeline,and designed for processing HⅠ21 cm spectra.Furthermore,we investigate different calibration techniques and assess the dependence of the gain parameter on the time and environmental factors.A comparison is carried out in various observation modes(e.g.,tracking and scanning modes)to determine the flux density gain(G),revealing insignificant discrepancies in G among different methods.Long-term monitoring data shows a linear correlation between G and atmospheric temperature.After subtracting the G-Temperature dependence,the dispersion of G is reduced to<3%over a one-year timescale.The stability of the receiver response of Five-hundred-meter Aperture Spherical radio Telescope(FAST)is considered sufficient to facilitate HⅠobservations that can accommodate a moderate error in flux calibration(e.g.,>~5%)when utilizing a constant G for calibration purposes.Our study will serve as a useful addition to the results provided by Jiang et al.Detailed measurement of G for the 19 beams of FAST,covering the frequency range 1000-1500 MHz,can be found on the Hi FAST homepage:https://hifast.readthedocs.io/fluxgain.
