检索结果-南通市图书馆

Introduction to the environmental monitoring instruments for LOT

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2020年第6期20卷 131-140页

作者： Jian-Feng Wang Jian-Feng Tian Xian-Qun Zeng Tao-Ran Li Yong Zhao Yue Wang Hua-Lin Chen Xiao-Jun Jiang Key Laboratory of Optical Astronomy National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China National Astronomical Observatories/Nanjing Institute of Astronomical Optics&Technology Chinese Academy of SciencesNanjing 210042China School of Astronomy and Space Science University of Chinese Academy of SciencesBeijing 100049China

The Large Optical/infrared Telescope(LOT)is a ground-based 12 m diameter optical/infrared telescope,which is proposed to be built in the western part of China in the next *** select the best site which satisfies the construction and future operation of LOT,data monitoring and comparing are required for all the candidate *** comparison of most of the instruments was done at Xinglong *** instruments include weather station,all sky camera,sky background meter and differential image motion monitor(DIMM).This paper introduces the instruments used in LOT site monitoring and the instruments *** results show that the instrument is stable and the data uniformity of the identical instruments is *** paper provides a fundamental description of LOT site monitoring.

关键词： atmospheric effects light pollution site testing

Quantitative Analysis of Seeing with Height and Time at Muztagh-Ata Site Based on ERA5 Database

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2024年第1期24卷 87-95页

作者： Xiao-Qi Wu Cun-Ying Xiao Ali Esamdin Jing Xu Ze-Wei Wang Luo Xiao Institute for Frontiers in Astronomy and Astrophysics Beijing Normal UniversityBeijing 102206China Department of Astronomy Beijing Normal UniversityBeijing 100875China Xinjiang Astronomical Observatory Chinese Academy of SciencesUrumqi 830011China University of Chinese Academy of Sciences Beijing 100049China

Seeing is an important index to evaluate the quality of an astronomical *** estimate seeing at the Muztagh-Ata site with height and time quantitatively,the European Centre for Medium-Range Weather Forecasts reanalysis database(ERA5)is *** calculated from ERA5 is compared consistently with the Differential Image Motion Monitor seeing at the height of 12 *** show that seeing decays exponentially with height at the Muztagh-Ata *** decays the fastest in fall in 2021 and most slowly with height in *** seeing condition is better in fall than in *** median value of seeing at 12 m is 0.89 arcsec,the maximum value is1.21 arcsec in August and the minimum is 0.66 arcsec in *** median value of seeing at 12 m is 0.72arcsec in the nighttime and 1.08 arcsec in the *** is a combination of annual and about biannual variations with the same phase as temperature and wind speed indicating that seeing variation with time is influenced by temperature and wind *** Richardson number Ri is used to analyze the atmospheric stability and the variations of seeing are consistent with Ri between *** quantitative results can provide an important reference for a telescopic observation strategy.

关键词： site testing atmospheric effects methods:data analysis telescopes Earth

Wind Environment Analysis of Ground-based Optical Observatory

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2022年第4期22卷 11-20页

作者： Tao-Ran Li Xiao-Jun Jiang Key Laboratory of Optical Astronomy National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China

The telescopes and the infrastructures may alter the local wind environment around the observatory and further affect the observing *** the completion of site testing,it is necessary to analyze the wind environment of the entire site and plan the telescope layout to make use of the excellent conditions scientifically and *** a typical observatory as an example,the effect of topographical features on the wind environment and the mutual interference between telescope enclosures are analyzed by using the Computational Fluid Dynamics(CFD)*** CFD simulations are compared with the seeing data from the Differential Image Motion Monitor,and the results are in good agreement,which verifies the effectiveness of the CFD *** results of wind environment analysis can provide reasonable suggestions for site layout and construction,reducing the interference effects and improving the observing environment.

关键词： methods:numerical telescopes atmospheric effects turbulence

在线全文

学校读者我要写书评

暂无评论

The AIMS Site Survey

Research in Astronomy and Astrophysics 2023年第11期23卷 14-24页

作者： Xing-Ming Bao Jian Wang Shuai Jing Yuan-Yong Deng Dong-Guang Wang Key Laboratory of Solar Activity National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China

This paper reports site survey results for the Infrared System for the Accurate Measurement of Solar Magnetic Field, especially in Saishiteng Mountain, Qinghai, China. Since 2017, we have installed a weather station,spectrometers for precipitable water vapor, and Solar Differential Image Motion Monitor, and have carried out observations on weather elements, precipitable water vapor, and daytime seeing conditions for more than one year in almost all candidates. At Mt. Saishiteng, the median value of daytime precipitable water vapor is 5.25 mm and its median value in winter season is 2.1 mm. The median value of the Fried parameter of daytime seeing observation at Saishiteng Mountain is 3.42 cm. Its solar direct radiation data show that solar average observable time is 446 minutes per day and premium time is 401 minutes per day in 2019 August.

关键词： site testing atmospheric effects methods:analytical

Astronomy from Dome A in Antarctica

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2020年第10期20卷 353-384页

作者： Zhaohui Shang National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China

Dome A in Antarctica has been demonstrated to be the best site on earth for optical,infrared,and terahertz astronomical observations by more and more evidence,such as excellent free-atmosphere seeing,extremely low perceptible water vapor,low sky background,and continuous dark time,*** this paper,we present a complete picture of the development of astronomy at Dome A from the very beginning,review recent progress in time-domain astronomy,demonstrate exciting results of the site testing,and address the challenges in *** proposed projects are briefly discussed.

关键词： instrumentation:miscellaneous methods:observational techniques:miscellaneous telescopes atmospheric effects site testing stars:variables:general

Two-telescope-based solar seeing profile measurement simulation

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2021年第12期21卷 305-314页

作者： Zi-Yue Wang De-Qing Ren Raffi Saadetian National Astronomical Observatories/Nanjing Institute of Astronomical Optics&Technology Chinese Academy of SciencesNanjing 210042China CAS Key Laboratory of Astronomical Optics&Technology Nanjing Institute of Astronomical Optics&TechnologyNanjing 210042China University of Chinese Academy of Sciences Beijing 100049China Physics&Astronomy Department California State University NorthridgeCalifornia 91330-8268USA

Measurements of the daytime seeing profile of the atmospheric turbulence are crucial for evaluating a solar astronomical site so that research on the profile of the atmospheric turbulence as a function of altitude C_(n)^(2)(h_(n))becomes more and more critical for performance estimation and optimization of future adaptive optics(AO)including the multi-conjugate adaptive optics(MCAO)***,the S-DIMM+method has been successfully used to measure daytime turbulence profiles above the New Solar Telescope(NST)on Big Bear ***,such techniques are limited by the requirement of using a large solar telescope which is not realistic for a new potential astronomical ***,the AMASP(advanced multiple-aperture seeing profiler)method is more portable and has been proved that can reliably retrieve the seeing profile up to 16 km with the Dunn Solar Telescope(DST)on the National Solar Observatory(Townson,Kellerer et al.).But the turbulence of the ground layer is calculated by combining A-MASP and S-DIMM+(Solar Differential Image Motion Monitor+)due to the limitation of the twoindividual-telescopes *** solve these problems,we introduce the two-telescope seeing profiler(TTSP)which consists of two portable individual *** simulations have been conducted to evaluate the performance of *** find our TTSP can effectively retrieve seeing profiles of four turbulence layers with a relative error of less than 4%and is dependable for actual seeing measurement.

关键词： turbulence atmospheric effects sun:granulation

Attitude dynamics and control of spacecraft using geomagnetic Lorentz force

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2015年第1期15卷 127-144页

作者： Yehia A.Abdel-Aziz Muhammad Shoaib National Research Institute of Astronomy and Geophysics (NRIAG) Helwan Cairo 11721Egypt University of Hail Department of Mathematics PO BOX 2440 Kingdom of Saudi Arabia

Attitude stabilization of a charged rigid spacecraft in Low Earth Orbit using torques due to Lorentz force in pitch and roll directions is considered. A spacecraft that generates an electrostatic charge on its surface in the Earth’s magnetic field will be subject to perturbations from the Lorentz force. The Lorentz force acting on an electrostatically charged spacecraft may provide a useful thrust for controlling a spacecraft’s orientation. We assume that the spacecraft is moving in the Earth’s magnetic field in an elliptical orbit under the effects of gravitational, geomagnetic and Lorentz torques. The magnetic field of the Earth is modeled as a non-tilted dipole.A model incorporating all Lorentz torques as a function of orbital elements has been developed on the basis of electric and magnetic fields. The stability of the spacecraft orientation is investigated both analytically and numerically. The existence and stability of equilibrium positions is investigated for different values of the charge to mass ratio（α＊）. Stable orbits are identified for various values of α＊. The main parameters for stabilization of the spacecraft are α＊and the difference between the components of the moment of inertia for the spacecraft.

关键词： space vehicles atmospheric effects celestial mechanics kinematics and dynamics

A Wideband Microwave Holography Methodology for Reflector Surface Measurement of Large Radio Telescopes

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2022年第9期22卷 140-151页

作者： Zan Wang De-Qing Kong Hong-Bo Zhang Xin-Ying Zhu Ze-Xin Liu Yu-Chen Liu Key Laboratory of Lunar and Deep Space Exploration National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100010China University of Chinese Academy of Sciences Beijing 100049China

Most reflector surface holographic measurements of a large radio telescope utilize a geostationary satellite as the signal source. The shortcoming is that those measurements could only be done at a limited elevation angle due to the satellite’s relatively stationary state. This paper proposed a new wideband microwave holographic measurement method based on radio sources to achieve full-elevation-angle measurement with small size reference antenna. In theoretical derivation, the time delay and phase change due to path length and device difference between the antenna under test and reference antenna are compensated first. Then the correct method of wideband holography effect, which is because of antenna pattern differing under different wavelengths when receiving a wideband signal, is presented. To verify the proposed methodology, a wideband microwave holographic measurement system is established, the data processing procedure is illustrated, and the reflector surface measurement experiments on a 40 m radio telescope at different elevation angles are conducted. The result shows that the primary reflector surface root-mean-square at around elevation angles of 28°, 44°, 49°, and 75° are respectively 0.213 mm, 0.170 mm, 0.188 mm, and 0.199 mm. It is basically consistent with the real data, indicating that the proposed wideband microwave holography methodology is feasible.

关键词： astronomical instrumentation methods and techniques telescopes methods:analytical atmospheric effects

The New Wuqing 70 m Radio Telescope and Measurements of Main Electronic Properties in the X-band

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2022年第3期22卷 122-132页

作者： De-Qing Kong Chun-Lai Li Hong-Bo Zhang Yan Su Jian-Jun Liu Xin-Ying Zhu Jun-Duo Li Xi-Ping Xue Chen Li Key Laboratory of Lunar and Deep Space Exploration National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China

The new Wuqing 70 m radio telescope is first used for the downlink data reception in the first Mars exploration mission of China,and will be used for the other deep space communications and radio astronomical observations in the *** main specifications and measurement results of some properties in the X-band are introduced in this paper,such as pointing calibration,gain and efficiency,system noise temperature,system equivalent flux density,and variations with *** 23 parameters pointing calibration model considering the atmospheric refraction correction in real time is presented in the telescope,and the pointing accuracy reaches 570 in azimuth direction and 607 in elevation direction for different weather *** than 62%efficiencies are achieved at full elevation range,and more than 70%in the *** system equivalent flux density of the X-band in the mid-elevation reaches 26 Jy.

关键词： telescopes astronomical instrumentation methods and techniques atmospheric effects