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
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
The Large Sky Area Multi-Object Fiber Spectroscopic Telescope（LAMOST） is the largest existing spectroscopic survey telescope, having 32 scientific charge-coupled-device（CCD） cameras for acquiring spectra. Stabilit...The Large Sky Area Multi-Object Fiber Spectroscopic Telescope（LAMOST） is the largest existing spectroscopic survey telescope, having 32 scientific charge-coupled-device（CCD） cameras for acquiring spectra. Stability and automation of the camera-control software are essential, but cannot be provided by the existing system. The Remote Telescope System 2 nd Version（RTS2） is an open-source and automatic observatory-control system. However, all previous RTS2 applications were developed for small telescopes. This paper focuses on implementation of an RTS2-based camera-control system for the 32 CCDs of LAMOST. A virtual camera module inherited from the RTS2 camera module is built as a device component working on the RTS2 framework. To improve the controllability and robustness, a virtualized layer is designed using the master-slave software paradigm, and the virtual camera module is mapped to the 32 real cameras of LAMOST. The new system is deployed in the actual environment and experimentally tested. Finally, multiple observations are conducted using this new RTS2-frameworkbased control system. The new camera-control system is found to satisfy the requirements for automatic camera control in LAMOST. This is the first time that RTS2 has been applied to a large telescope, and provides a referential solution for full RTS2 introduction to the LAMOST observatory control system.展开更多
We present the estimation of solar observation with the Five-hundred-meter Aperture Spherical radio Telescope(FAST).For both the quiet Sun and the Sun with radio bursts,when pointing directly to the Sun,the total powe...We present the estimation of solar observation with the Five-hundred-meter Aperture Spherical radio Telescope(FAST).For both the quiet Sun and the Sun with radio bursts,when pointing directly to the Sun,the total power received by FAST would be out of the safe operational range of the signal chain,even resulting in damage to the receiver.As a conclusion,the Sun should be kept at least~2°away from the main beam during observations at~1.25 GHz.The separation for lower frequency should be larger.For simplicity,the angular separation between the FAST beam and the Sun is suggested to be~5°for observations at 200 MHz or higher bands.展开更多
The increasing number of space debris has created an orbital debris environment that poses increasing impact risks to existing space systems and human space flights. For the safety of in-orbit spacecrafts, we should o...The increasing number of space debris has created an orbital debris environment that poses increasing impact risks to existing space systems and human space flights. For the safety of in-orbit spacecrafts, we should optimally schedule surveillance tasks for the existing facilities to allocate re- sources in a manner that most significantly improves the ability to predict and detect events involving affected spacecrafts. This paper analyzes two criteria that mainly affect the performance of a scheduling scheme and introduces an artificial intelligence algorithm into the scheduling of tasks of the space debris surveillance network. A new scheduling algorithm based on the particle swarm optimization algorithm is proposed, which can be implemented in two different ways： individual optimization and joint optimiza- tion. Numerical experiments with multiple facilities and objects are conducted based on the proposed algorithm, and simulation results have demonstrated the effectiveness of the proposed algorithm.展开更多
We describe the photometric calibration of the Lunar-based Ultraviolet Telescope（LUT）, the first robotic astronomical telescope working on the lunar surface, for its first six months of operation on the lunar surfac...We describe the photometric calibration of the Lunar-based Ultraviolet Telescope（LUT）, the first robotic astronomical telescope working on the lunar surface, for its first six months of operation on the lunar surface. Two spectral datasets（set A and B） from near-ultraviolet（NUV） to the optical band were constructed with 44 International Ultraviolet Explorer（IUE） standards, because of the LUT＇s relatively wide wavelength coverage. Set A was obtained by extrapolating the IUE NUV spectra（λ 〈 3200 ） to the optical band based upon the theoretical spectra of stellar atmosphere models. Set B was composed of theoretical spectra from 2000 to 8000 extracted from the same model grid. In total, seven standards have been observed in15 observational runs until May 2014. The calibration results show that the photometric performance of LUT is highly stable in its first six months of operation. The magnitude zero points obtained from the two spectral datasets are also consistent with each other, i.e., zp = 17.54 ± 0.09 mag（set A） and zp = 17.52 ± 0.07 mag（set B）.展开更多
DATE5, a 5 m telescope for terahertz exploration, was proposed for acquiring observations at Dome A, Antarctica. In order to observe the terahertz spectrum, it is necessary to maintain high surface accuracy in the the...DATE5, a 5 m telescope for terahertz exploration, was proposed for acquiring observations at Dome A, Antarctica. In order to observe the terahertz spectrum, it is necessary to maintain high surface accuracy in the the antenna when it is exposed to Antarctic weather conditions. Structural analysis shows that both machined aluminum and carbon fiber reinforced plastic （CFRP） panels can meet surface accuracy requirements. In this paper, one design concept based on aluminum panels is introduced. This includes panel layout, details on panel support, design of a CFRP backup structure, and detailed finite element analysis. Modal, gravity and thermal analysis are all performed and surface deformations of the main reflector are evaluated for all load cases. At the end of the paper, the manufacture of a prototype panel is also described. Based on these results, we found that using smaller aluminum reflector panels has the potential to meet the surface requirements in the harsh Dome A environment.展开更多
A bistatic space debris observation system using a radio telescope as the receiving part is introduced. The detection capability of the system at different working frequencies is analyzed based on real instruments. Th...A bistatic space debris observation system using a radio telescope as the receiving part is introduced. The detection capability of the system at different working frequencies is analyzed based on real instruments. The detection range of targets with a fixed radar cross section and the detection ability of small space debris at a fixed range are discussed. The simulations of this particular observation system at different transmitting powers are also implemented and the detection capability is discussed. The simulated results approximately match the actual experiments. The analysis in this paper provides a theoretical basis for developing a space debris observation system that can be built in China.展开更多
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.
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supported by the National Key Research and Development Program of China(Grant No.2016YFE0100300)the Joint Research Fund in Astronomy(Grant Nos.U1531132,U1631129 and U1231205)under cooperative agreement between the National Natural Science Foundation of China(NSFC)+1 种基金the Chinese Academy of Sciences(CAS)the National Natural Science Foundation of China(Grant Nos.11603044,11703044,11503042,11403009and 11463003)
文摘The Large Sky Area Multi-Object Fiber Spectroscopic Telescope（LAMOST） is the largest existing spectroscopic survey telescope, having 32 scientific charge-coupled-device（CCD） cameras for acquiring spectra. Stability and automation of the camera-control software are essential, but cannot be provided by the existing system. The Remote Telescope System 2 nd Version（RTS2） is an open-source and automatic observatory-control system. However, all previous RTS2 applications were developed for small telescopes. This paper focuses on implementation of an RTS2-based camera-control system for the 32 CCDs of LAMOST. A virtual camera module inherited from the RTS2 camera module is built as a device component working on the RTS2 framework. To improve the controllability and robustness, a virtualized layer is designed using the master-slave software paradigm, and the virtual camera module is mapped to the 32 real cameras of LAMOST. The new system is deployed in the actual environment and experimentally tested. Finally, multiple observations are conducted using this new RTS2-frameworkbased control system. The new camera-control system is found to satisfy the requirements for automatic camera control in LAMOST. This is the first time that RTS2 has been applied to a large telescope, and provides a referential solution for full RTS2 introduction to the LAMOST observatory control system.
基金supported by National Key R&D Program of China No. 2018YFE0202900 and National SKA Program of China No. 2020SKA0120100supported by the Specialized Research Fund for State Key Laboratories and National Natural Science Foundation of China (NSFC, Grant Nos. 11703047, 11773041, U2031119, 12041303, 12173052, 12003047 and 12173053)+2 种基金supported by the CAS “Light of West China” Programsupported by the Youth Innovation Promotion Association of CAS (id. 2018075)the CAS “Light of West China” Program and the Science and Technology Program of Guizhou Province ([2021] 4001)。
文摘We present the estimation of solar observation with the Five-hundred-meter Aperture Spherical radio Telescope(FAST).For both the quiet Sun and the Sun with radio bursts,when pointing directly to the Sun,the total power received by FAST would be out of the safe operational range of the signal chain,even resulting in damage to the receiver.As a conclusion,the Sun should be kept at least~2°away from the main beam during observations at~1.25 GHz.The separation for lower frequency should be larger.For simplicity,the angular separation between the FAST beam and the Sun is suggested to be~5°for observations at 200 MHz or higher bands.
基金funded by the National Natural Science Foundation of China (Grant No. 11503044)by the Young Researcher Grant of National Astronomical Observatories, Chinese Academy of Sciences
文摘The increasing number of space debris has created an orbital debris environment that poses increasing impact risks to existing space systems and human space flights. For the safety of in-orbit spacecrafts, we should optimally schedule surveillance tasks for the existing facilities to allocate re- sources in a manner that most significantly improves the ability to predict and detect events involving affected spacecrafts. This paper analyzes two criteria that mainly affect the performance of a scheduling scheme and introduces an artificial intelligence algorithm into the scheduling of tasks of the space debris surveillance network. A new scheduling algorithm based on the particle swarm optimization algorithm is proposed, which can be implemented in two different ways： individual optimization and joint optimiza- tion. Numerical experiments with multiple facilities and objects are conducted based on the proposed algorithm, and simulation results have demonstrated the effectiveness of the proposed algorithm.
基金Supported by the National Natural Science Foundation of China
文摘We describe the photometric calibration of the Lunar-based Ultraviolet Telescope（LUT）, the first robotic astronomical telescope working on the lunar surface, for its first six months of operation on the lunar surface. Two spectral datasets（set A and B） from near-ultraviolet（NUV） to the optical band were constructed with 44 International Ultraviolet Explorer（IUE） standards, because of the LUT＇s relatively wide wavelength coverage. Set A was obtained by extrapolating the IUE NUV spectra（λ 〈 3200 ） to the optical band based upon the theoretical spectra of stellar atmosphere models. Set B was composed of theoretical spectra from 2000 to 8000 extracted from the same model grid. In total, seven standards have been observed in15 observational runs until May 2014. The calibration results show that the photometric performance of LUT is highly stable in its first six months of operation. The magnitude zero points obtained from the two spectral datasets are also consistent with each other, i.e., zp = 17.54 ± 0.09 mag（set A） and zp = 17.52 ± 0.07 mag（set B）.
基金supported by the National Natural Science Foundation of China(NSFC,Grant Nos.11190014,11503093,11403109 and 11373073)the Natural Science Foundation of Jiangsu Province(Grant No.BK20141042)
文摘DATE5, a 5 m telescope for terahertz exploration, was proposed for acquiring observations at Dome A, Antarctica. In order to observe the terahertz spectrum, it is necessary to maintain high surface accuracy in the the antenna when it is exposed to Antarctic weather conditions. Structural analysis shows that both machined aluminum and carbon fiber reinforced plastic （CFRP） panels can meet surface accuracy requirements. In this paper, one design concept based on aluminum panels is introduced. This includes panel layout, details on panel support, design of a CFRP backup structure, and detailed finite element analysis. Modal, gravity and thermal analysis are all performed and surface deformations of the main reflector are evaluated for all load cases. At the end of the paper, the manufacture of a prototype panel is also described. Based on these results, we found that using smaller aluminum reflector panels has the potential to meet the surface requirements in the harsh Dome A environment.
基金Supported by the National Natural Science Foundation of China
文摘A bistatic space debris observation system using a radio telescope as the receiving part is introduced. The detection capability of the system at different working frequencies is analyzed based on real instruments. The detection range of targets with a fixed radar cross section and the detection ability of small space debris at a fixed range are discussed. The simulations of this particular observation system at different transmitting powers are also implemented and the detection capability is discussed. The simulated results approximately match the actual experiments. The analysis in this paper provides a theoretical basis for developing a space debris observation system that can be built in China.
