分类： 天文学 >> 天文仪器与技术 提交时间： 2025-06-03 合作期刊: 《Astronomical Techniques and Instruments》
Yiming Mao
Liang Ge
Yongkang Sun
Jingxiao Luo
Xunhao Chen
Renhao Ye
Lifu Zhang
Minglin Wang
E Xiang
Zhizhong Zhou
Hong Wu
摘要： This paper presents a comprehensive analysis of the photometric system of the University of Chinese Academy of Sciences 70 cm Telescope located at the Yan-qi Lake campus of the University of Chinese Academy of Sciences. We evaluated the linearity, bias stability, and dark current of the camera. Utilizing the Johnson-Cousins Blue-Visible-Red-Infrared filter system and an Andor DZ936 charge-coupled device camera, we conducted extensive observations of Landolt standard stars to determine the color terms, atmospheric extinction coefficients, photometric zero-points, and the sky background brightness. The results indicate that this telescope demonstrates excellent performance in photometric calibration and good system performance overall, meeting the requirements for limited scientific research and teaching purposes.
分类： 天文学 >> 天文仪器与技术 提交时间： 2024-09-30 合作期刊: 《天文技术与仪器（英文）》
摘要： Wind loads have instantaneity and turbulence characteristics that will lead to pointing errors in antenna structures, and these errors cannot be ignored in high-frequency observations. Using the Tianma 65 m radio telescope (TMRT) as an example object, the pointing errors caused by wind loads are investigated using an accelerometer system. First, the resonant frequency range of the antenna structure is used for reference to acquire useful signals through the bandpass filtering method. Then, the direct current (DC) component of these signals is filtered out using the fast discrete Fourier transform method, and the baseline of the acceleration is corrected using the least-squares method. Finally, the acceleration integral is solved approximately using the discrete trapezoidal area method, and the structural vibration displacement of the antenna is determined using a double integral of acceleration. The pointing errors are then obtained based on the displacement relationship between the primary and subreflector surfaces. When the wind speed is 3.2 m/s, the antenna pitch angle is 61.7° and the wind direction angle is 80°, the generated pitch pointing error is 3.05'', and the azimuth pointing error is 1.14''. These results are consistent with those obtained via inclinometer measurements, thus validating the signal processing method and the pointing error calculation method proposed in this paper. The research methods and data analysis results reported here provide a basis for further windinduced pointing error correction studies.
分类： 天文学 >> 天文仪器与技术 提交时间： 2024-09-30 合作期刊: 《天文技术与仪器（英文）》
ZhengxiongSun
JinqingWang
LinfengYu
YongchenJiang
ZhengLou
YongbinJiang
RongbinZhao
QianYe
QinghuiLiu
GuangliWang
摘要： The surface accuracy of a radio telescope is directly related to its operational efficiency and detection sensitivity. This is crucial under high-frequency observation conditions, where surface shape errors need to be controlled to within 1/16 of the working wavelength. In addition, the primary reflector of large radio telescopes is subject to dynamic deformation, caused by factors such as gravity and thermal effects. This paper presents a method for detecting the surface shape of radio telescopes using radio interferometry techniques combined with active reflector adjustment technology. This enables accurate assessment and correction of surface errors, ensuring the electrical performance of the radio telescope. This study investigates the practical applications of high-precision measurement techniques, such as microwave holography, out-of-focus holography, and wavefront distortion methods at the Tianma 65 m radio telescope (TMRT). Furthermore, the study presents the construction method of gravity models at different elevation angles and demonstrates the efficacy of the active reflector model. The results of the measurements indicate that the application of these methods to the TMRT has led to a notable enhancement of the accuracy of the primary reflector and a substantial improvement in efficiency in the Q-band. Through a process of iterative measurements and adjustments, the surface shape error is ultimately reduced to 0.28 mm root mean square (RMS).
分类： 天文学 >> 天文仪器与技术 提交时间： 2024-09-30 合作期刊: 《天文技术与仪器（英文）》
摘要： This paper presents an innovative surrogate modeling method using a graph neural network to compensate for gravitational and thermal deformation in large radio telescopes. Traditionally, rapid compensation is feasible for gravitational deformation but not for temperature-induced deformation. The introduction of this method facilitates realtime calculation of deformation caused both by gravity and temperature. Constructing the surrogate model involves two key steps. First, the gravitational and thermal loads are encoded, which facilitates more efficient learning for the neural network. This is followed by employing a graph neural network as an end-to-end model. This model effectively maps external loads to deformation while preserving the spatial correlations between nodes. Simulation results affirm that the proposed method can successfully estimate the surface deformation of the main reflector in real-time and can deliver results that are practically indistinguishable from those obtained using finite element analysis. We also compare the proposed surrogate model method with the out-of-focus holography method and yield similar results.
分类： 天文学 >> 天文仪器与技术 提交时间： 2024-09-30 合作期刊: 《天文技术与仪器（英文）》
摘要： A time and frequency system is a critical component of Very Long Baseline Interferometry (VLBI) stations, providing stable and reliable standards that directly impact data processing quality. At the Tianma 65 m radio telescope(TMRT), this system has been meticulously designed to ensure long-term reliability and high performance. It incorporates high-performance hydrogen atomic clocks, high-precision time standards, automatic signal switching, and robust system software. This comprehensive approach has enabled the system to achieve long-term reliable operation, successfully supporting both major national engineering tasks and daily scientific observations. The effectiveness of the system is evidenced by its consistent delivery of the precision and stability required for radio astronomy. This article provides an in-depth exploration of the design and operation of the time and frequency system at the Tianma 65 m telescope, examining various aspects of its architecture, implementation, and performance. By sharing these insights, we aim to contribute knowledge that could benefit similar systems at other VLBI stations, greatly advancing radio astronomy infrastructure.
分类： 天文学 >> 天文仪器与技术 提交时间： 2024-09-26 合作期刊: 《天文技术与仪器（英文）》
BiaoDu
YuanpengZheng
GuoxiLiu
YifanZhang
WancaiZhang
LijunZhang
ShunyouQin
ZhiqiangShen
QinghuiLiu
BinLi
JinqingWang
摘要： The Tianma 65 m radio telescope (TMRT) at Shanghai is a fully steerable single-dish radio telescope in China, operating at centimeter to millimeter wavelengths (1.25 GHz to 50 GHz). This paper presents details on the main specifications, design, performance analysis, testing, and construction of the telescope antenna. The measured total efficiency is better than 50% over the whole elevation angle range, first sidelobe levels are less than −20 dB, antenna system noise temperatures are less than 70 K at 30° elevation angle, and pointing accuracy is less than 3″. The measured and calculated results are in good agreement, verifying the effectiveness of the design and analysis.
分类： 天文学 >> 天文仪器与技术 提交时间： 2024-09-26 合作期刊: 《天文技术与仪器（英文）》
QinghuiLiu
ZhiqiangShen
XiaoyuHong
QianYe
BinLi
JinqingWang
RongbingZhao
LiFu
WeiyeZhong
LinglingWang
JuanLi
ZhenYan
WuJiang
BoXia
摘要： The Shanghai Tianma 65 m radio telescope (TMRT) is a large, fully rotatable radio telescope with multiple scientific purposes. The main body of the telescope and four low-frequency receiving systems, including L, C, and S/X bands, were completed between 2008 and 2012. From 2013 to 2017, four high-frequency receiving systems, including Ku, K, Ka, and Q bands, were constructed and their performance was comprehensively tested. There are three main innovations. (1) A fully movable large radio telescope system with advanced performance and complete functions has been built. (2) An advanced, reliable main reflector adjustment system has been completed, overcoming gravity deformation and creating a large antenna with a main reflective surface accuracy of 0.28 mm (root mean square) for any elevation. (3) Five innovative technologies have been developed to achieve high-precision pointing in any direction within 3 ″. The TMRT has made a crucial contribution to the orbital measurement and positioning of China’s lunar and deep space probes. Significantly enhancing China's ability to participate in international VLBI observations and radio astronomy, this has facilitated a series of achievements in observational radio astronomical research, in areas such as VLBI, spectral lines, and pulsars.
分类： 天文学 >> 天文仪器与技术 提交时间： 2024-06-06 合作期刊: 《天文技术与仪器（英文）》
摘要：The Educational Adaptive-optics Solar Telescope (EAST) at the Shanghai Astronomy Museum has been running routine astronomical observations since 2021. It is a 65-cm-aperture Gregorian solar telescope for scientific education, outreach, and research. The telescope system is designed in an “open” format so that the solar tower architecture can be integrated with it, and visitors can watch the observations live from inside the tower. Equipped with adaptive optics, a high-resolution imaging system, and an integral field unit spectro-imaging system, this telescope can obtain high-resolution solar images in the TiO and Hα bands, and perform spectral image reconstruction using 400 optical fibers at selected wavelengths. It can be used not only in public education and scientific outreach but also in solar physics research.
分类： 天文学 >> 天文仪器与技术 提交时间： 2024-04-16 合作期刊: 《天文技术与仪器（英文）》
Peng Jiang
Rurong Chen
Hengqian Gan
Jinghai Sun
Boqin Zhu
Hui Li
Weiwei Zhu
Jingwen Wu
Xuelei Chen
Haiyan Zhang
Tao An
摘要：The Five-hundred-meter Aperture Spherical Radio Telescope (FAST) Core Array is a proposed extension of FAST, integrating 24 secondary 40-m antennas implanted within 5 km of the FAST site. This original array design will combine the unprecedented sensitivity of FAST with a high angular resolution (4.3" at a frequency of 1.4 GHz), thereby exceeding the capabilities at similar frequencies of next-generation arrays such as the Square Kilometre Array Phase 1 or the next-generation Very Large Array. This article presents the technical specifications of the FAST Core Array, evaluates its potential relatively to existing radio telescope arrays, and describes its expected scientific prospects. The proposed array will be equipped with technologically advanced backend devices, such as real-time signal processing systems. A phased array feed receiver will be mounted on FAST to improve the survey efficiency of the FAST Core Array, whose broad frequency coverage and large field of view（ FOV） will be essential to study transient cosmic phenomena such as fast radio bursts and gravitational wave events, to conduct surveys and resolve structures in neutral hydrogen galaxies, to monitor or detect pulsars, and to investigate exoplanetary systems. Finally, the FAST Core Array can strengthen China's major role in the global radio astronomy community, owing to a wide range of potential scientific applications from cosmology to exoplanet science.
分类： 天文学 >> 天文仪器与技术 提交时间： 2024-02-07 合作期刊: 《天文技术与仪器（英文）》
Meiting Yang
Yong Yu
Liangliang Wang
Zhengjun Shang
Changshun Liu
Lixin Zheng
Zhendong Chen
Jing Yang
Dongmei Da
Shan Dong
Shiyin Shen
Zhenghong Tang
Jianhai Zhao
摘要：Before charge-coupled device detectors became widely employed in observational astronomy, for more than a hundred years, the main detection method was photography on astronomical glass plates. Recently, in order to preserve these historical data and maintain their usability, the International Astronomical Union has appealed to all countries for global digitization of astronomical plates by developing or adopting advanced digitization technology. Specialized digitizers with high precision and high measuring speed represent key equipment for this task. The Shanghai Astronomical Observatory and the Nishimura Co., Ltd in Japan cooperated between 2013 and 2016 to develop the first Chinese high-precision astronomical plate digitizer, which was then used for complete digitization of all nighttime-observation astronomical plates in China. Then, in 2019–2021, the Shanghai Astronomical Observatory independently developed new models of plate digitizers that enabled countries such as Uzbekistan and Italy to digitize their astronomical plates. Additionally, a new high-precision and multifunction digitizer was also used to digitize valuable microscope slides from the Shanghai Natural History Museum, providing a successful example of crossdomain application of high-precision digitization technology.
分类： 天文学 >> 天文仪器与技术 提交时间： 2024-02-07 合作期刊: 《天文技术与仪器（英文）》
JUST Team
Chengze Liu
Ying Zu
Fabo Feng
Zhaoyu Li
Yu Yu
Hua Bai
Xiangqun Cui
Bozhong Gu
Yizhou Gu
Jiaxin Han
Yonghui Hou
Zhongwen Hu
Hangxin Ji
Yipeng Jing
Wei Li
Zhaoxiang Qi
Xianyu Tan
Cairang Tian
Dehua Yang
摘要：The Jiao Tong University Spectroscopic Telescope (JUST) is a 4.4-meter f/6.0 segmented-mirror telescope dedicated to spectroscopic observations. The JUST primary mirror is composed of 18 hexagonal segments, each with a diameter of 1.1 m. JUST provides two Nasmyth platforms for placing science instruments. One Nasmyth focus fits a field of view of 10 ′ and the other has an extended field of view of 1.2° with correction optics. A tertiary mirror is used to switch between the two Nasmyth foci. JUST will be installed at a site at Lenghu in Qinghai Province, China, and will conduct spectroscopic observations with three types of instruments to explore the dark universe, trace the dynamic universe, and search for exoplanets: (1) a multi-fiber (2000 fibers) medium-resolution spectrometer (R=4 000−5 000) to spectroscopically map galaxies and large-scale structure; (2) an integral field unit (IFU) array of 500 optical fibers and/or a long-slit spectrograph dedicated to fast follow-ups of transient sources for multi-messenger astronomy; (3) a high-resolution spectrometer (R~100 000) designed to identify Jupiter analogs and Earth-like planets, with the capability to characterize the atmospheres of hot exoplanets.
分类： 天文学 >> 天文学 提交时间： 2023-12-25
Yuting Wang
Ruiyang Zhao
Zhongxu Zhai
Kazuya Koyama
Will J. Percival
Hong Guo
Yin Li
Gong-Bo Zhao
Takahiro Nishimichi
Héctor Gil-Marín
Yonghao Feng
Hanyu Zhang
Yi Wu
摘要： The small-scale linear information in galaxy samples typically lost during non-linear growth can be restored to a certain level by the density field reconstruction, which has been demonstrated for improving the precision of the baryon acoustic oscillations (BAO) measurements. As proposed in the literature, a joint analysis of the power spectrum before and after the reconstruction enables an efficient extraction of information carried by high-order statistics. However, the statistics of the post#2;reconstruction density field are difficult to model. In this work, we circumvent this issue by developing an accurate emulator for the pre-reconstructed, post-reconstructed, and cross power spectra (Ppre, Ppost, Pcross) up to k = 0.5 h Mpc1 based on the Dark Quest N-body simulations. The accuracy of the emulator is at percent level, namely, the error of the emulated monopole and quadrupole of the power spectra is less than 1% and 5% of the ground truth, respectively. A fit to an example power spectra using the emulator shows that the constraints on cosmological parameters get largely improved using Ppre+Ppost+Pcross with kmax = 0.25 h Mpc1 , compared to that derived from Ppre alone, namely, the constraints on (Ωm, H0, 8) are tightened by 41% 55%, and the uncertainties of the derived BAO and RSD parameters (, , f8) shrink by 28% 54%, respectively. This highlights the complementarity among Ppre, Ppost and Pcross, which demonstrates the efficiency and practicability of a joint Ppre, Ppost and Pcross analysis for cosmological implications.
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