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Atmospheric Excitation of Time Variable Length-of-Day on Seasonal Scales

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chinese Journal of Astronomy and Astrophysics 2006年第1期6卷 120-124页

作者： li-hua Ma Yan-Ben {2. national astronomical Observatories Chinese Academy of Sciences Beijing 100012

We use the method of wavelet transform to analyze the time series of the Earth＇s rotation rate of the EOP （IERS） C04. The result shows that the seasonal （annual and semiannual） variation of the length-of-day （LOD） has temporal variability in its period length and amplitude. During 1965.0-2.01.0, the periods of the semiannual and annual components varied mainly from 175-day to 190-day and from 360-day to 370-day, respectively; while their amplitudes varied by more than 0.2.ms and 0.1 ms, respectively. Analyzing the axial component of atmospheric angular momentum （AAM） during this period, we have found that time-variations of period lengths and amplitudes also exist in the seasonal oscillations of the axial AAM and are in good consistency with those of the seasonal LOD change. The time variation of the axial AAM can explain largely the change of the LOD on seasonal scales.

关键词： Earth rotation -- seasonal variation -- wavelet transform

Support Vector Machine combined with K-Nearest Neighbors for Solar Flare Forecasting

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chinese Journal of Astronomy and Astrophysics 2007年第3期7卷 441-447页

作者： Rong li hua-Ning Wang {2. He Yan-Mei Cui Z{2.-Le Du national astronomical Observatories Chinese Academy of Sciences Beijing 100012

A method combining the support vector machine （SVM） the K-Nearest Neighbors （KNN）, labelled the SVM-KNN method, is used to construct a solar flare forecasting model. Based on a proven relationship between SVM and KNN, the SVM-KNN method improves the SVM algorithm of classification by taking advantage of the KNN algorithm according to the distribution of test samples in a feature space. In our flare forecast study, sunspots and 10cm radio flux data observed during Solar Cycle 2. are taken as predictors, and whether an M class flare will occur for each active region within two days will be predicted. The SVM- KNN method is compared with the SVM and Neural networks-based method. The test results indicate that the rate of correct predictions from the SVM-KNN method is higher than that from the other two methods. This method shows promise as a practicable future forecasting model.

关键词： Sun flare - Sun sunspot - Sun activity - Sun magnetic fields

The In-Flight Realtime Trigger and Localization Software of GECAM

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Research in Astronomy and Astrophysics 2024年第10期24卷 11-24页

作者： Xiao-Yun Zhao Shao-lin Xiong xiang-Yang Wen Xin-Qiao {2. Ce Cai Shuo Xiao Qi Luo Wen-Xi Peng Dong-Ya Guo Zheng-hua An Ke Gong jin-Yuan {2.ao Yan-Qiu Zhang Yue huang Lu {2. Xing Wen Fei Zhang jing Duan Chen-Wei Wang Dong-{2. Shi Peng Zhang Qi-Bin Yi Chao-Yang {2. Yan-Bing Xu Xiao-hua {2.ang Ya-Qing {2.u Da-{2. Zhang Xi-Lei Sun Fan Zhang Gang Chen huan-Yu Wang Sheng Yang Xiao-jing {2.u Min Gao Mao-Shun {2. jin-Zhou Wang Xing Zhou Yi Zhao Wang-Chen Xue Chao Zheng Jia-Cong {2.u Xing-Bo han jin-ling Qi Jia huang Ke-Ke Zhang Can Chen Xiong-Tao Yang Dong-Jie Hou Yu-Sa Wang Rui Qiao xiang Ma Xiao-Bo {2. Ping Wang Xin-Ying Song {2.-Ming Song Shi-Jie Zheng Bing {2. Hong-Mei Zhang Yue Zhu Wei Chen Jian-Jian He Zhen Zhang jin Hou Hong-Jun Wang Yan-Chao Hao xiang-Yu Wang Zong-Yuan Yang Zhi-Long Wen Zhi Chang Yuan-Yuan Du Rui Gao Xiao-Fei Lan Yan-Guo {2. Gang {2. Xu-Fang {2. Fang-Jun Lu Hong Lu Bin Meng Feng Shi Hui Wang Hui-Zhen Wang Yu-Peng Xu Jia-Wei Yang Xue-Juan Yang Shuang-Nan Zhang Chao-Yue Zhang Cheng-Mo Zhang Zhi-Cheng Tang Cheng Cheng Key Laboratory of Particle Astrophysics Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China University of chinese academy of sciences Chinese Academy of SciencesBeijing 100049China School of Information Science and Technology Southwest Jiaotong UniversityChengdu 611756China Key Laboratory of Stellar and Interstellar Physics and Department of Physics Xiangtan UniversityXiangtan 411105China Physics and Space Science College China West Normal UniversityNanchong 637002China Department of Astronomy Beijing Normal UniversityBeijing 100875China Innovation academy for Microsatellites of CAS Shanghai 201203China Changchun University of Science and Technology Changchun 130022China chinese academy of {2. South America Center for Astronomy National Astronomical ObservatoriesCASBeijing 100101China

Realtime trigger and localization of bursts are the key functions of GECAM,an all-sky gamma-ray monitor launched on 2.2. December *** developed a multifunctional trigger and localization software operating in the CPU of the GECAM Electronic *** onboard software has the following features:high trigger efficiency for real celestial bursts with a suppression of false triggers caused by charged particle bursts and background fluctuation,dedicated localization algorithm optimized for both short and long bursts,and low time latency of the trigger information which is downlinked through the Global Short Message Communication service of the global BeiDou navigation *** paper provides a detailed description of the design and development of the trigger and localization software system for *** covers the general design,workflow,the main functions,and the algorithms used in the *** paper also includes on-ground trigger tests using simulated gamma-ray bursts generated by a dedicated X-ray tube,as well as an overview of the performance for real celestial bursts during its in-orbit operation.

关键词： telescopes instrumentation:detectors methods:observational

Observation of spectral lines in the exceptional GRB 2.1009A

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Science China(Physics,Mechanics & Astronomy) 2024年第8期67卷 187-206页

作者： Yan-Qiu Zhang Shao-lin Xiong Ji-Rong Mao S{2.ng-Nan Zhang Wang-Chen Xue Chao Zheng Jia-Cong liu Zhen Zhang Xi-Lu Wang Ming-Yu Ge Shu-Xu Yi li-Ming Song Zheng-{2. An Ce Cai Xin-Qiao li Wen-Xi Peng Wen-Jun Tan Chen-Wei Wang xiang-Yang Wen Yue Wang Shuo Xiao Fan Zhang Peng Zhang Shi-Jie Zheng Key Laboratory of Particle Astrophysics Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China University of chinese academy of sciences Beijing 100049China Yunnan Observatories Chinese Academy of SciencesKunming 650011China Center for astronomical Mega-Science Chinese Academy of SciencesBeijing 100012China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of SciencesKunming 650216China College of Physics and Hebei Key Laboratory of Photophysics Research and Application Hebei Normal UniversityShijiazhuang 050024China Guizhou Provincial Key Laboratory of Radio Astronomy and Data Processing Guizhou Normal UniversityGuiyang 550001China College of Electronic and Information Engineering Tongji UniversityShanghai 201804China

As the brightest gamma-ray burst ever observed,GRB 2.1009A provided a precious opportunity to explore spectral line *** this article,we performed a comprehensive spectroscopy analysis of GRB 2.1009A jointly with GECAM-C and Fermi/GBM data to search for emission and absorption *** the first time we investigated the line feature throughout this GRB including the most bright part where many instruments suffered problems,and identified prominent emission lines in multiple time *** central energy of the Gaussian emission line evolves from about 37 to 6 MeV,with a nearly constant ratio(about 10%)between the line width and central ***,we find that both the central energy and the energy flux of the emission line evolve with time as a power law decay with power law index of–1 and–2.*** suggest that the observed emission lines most likely origin from the blue-shifted electron positron pair annihilation 511 ke V *** find that a standard high latitude emission scenario cannot fully interpret the observation,thus we propose that the emission line comes from some dense clumps with electron positron pairs traveling together with the *** this scenario,we can use the emission line to directly,for the first time,measure the bulk Lorentz factor of the jet(Γ)and reveal its time evolution(i.e.,Γ~t^(-1))during the prompt ***,we find that the flux of the annihilation line in the co-moving frame keeps *** discoveries of the spectral line features shed new and important lights on the physics of GRB and relativistic jet.

关键词： GRB GRB 2.1009A emission line

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日冕分米波射电甚短周期脉动的观测证据

天文学报 2003年第2期44卷 139-146页

作者：谢瑞祥汪敏施硕彪许春李维华颜毅华中国科学院国家天文台云南天文台昆明650011 中国科学院国家天文台北京100012

利用国家天文台云南天文台“分米波(700—1500 MHz)射电频谱仪”和“四波段太阳射电高时间分辨率同步观测系统”分别于2.01年6月2.日和1990年7月30日观测到了两个稀少事件,前者是一个小射电爆发,其上升相伴随有短周期(约2.、40和100毫秒... 详细信息

利用国家天文台云南天文台“分米波(700—1500 MHz)射电频谱仪”和“四波段太阳射电高时间分辨率同步观测系统”分别于2.01年6月2.日和1990年7月30日观测到了两个稀少事件,前者是一个小射电爆发,其上升相伴随有短周期(约2.、40和100毫秒)的脉动,后者是一个射电大爆发,在2.40 MHz上产生了周期约30毫秒的射电脉动。还着重讨论其甚短周期(如2.—40毫秒)的脉动现象,甚短周期脉动可能是归因干起源在日冕深处不稳定区域的哨声波束周期链对射电辐射的凋制,或沉降电子束驱动的静电高混杂波,经由波-波非线性相互作用导致甚短周期的射电脉动。

关键词：日冕射电辐射磁场脉动

New background quasars in the vicinity of the Andromeda Galaxy discovered with the Guoshoujing Telescope (LAMOST)

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Research in Astronomy and Astrophysics 2010年第7期10卷 612-620页

作者： Zhi-Ying Huo Xiao-Wei liu Hai-Bo Yuan Hui-hua Z{2.g Yong-Heng Zhao Jian-Jun Chen Zhong-Rui Bai Hao-Tong Z{2.g hua-Wei Z{2.g Ruben Garcia-Benito Mao-Sheng xiang Hong-liang Yan Juan-Juan Ren Shi-Wei Sun Yong Z{2.g Ye-Ping li Qi-Shuai Lu You Wang Ji-Jun Ni Hai Wang Department of Astronomy Peking University Beijing 100871 China Kavli Institute for Astronomy and Astrophysics Peking University Beijing 100871 China national astronomical Observatories Chinese Academy of Sciences Beijing 100012 China Department of Astronomy Beijing Normal University Beijing 100875 China Nanjing Institute of astronomical Optics ＆ Technology Chinese Academy of Sciences Nanjing 210042 China

We present preliminary analyses of spectra of quasar candidates in two Guoshoujing Telescope （GSJT, formerly named the Large Sky Area Multi-Object Fiber Spectroscopic Telescope - LAMOST） test fields near M 31 where one is close to the optical center of the disk and the other is towards the northeastern outskirts of the halo, obtained during the early stage of the GSJT commissioning in the last season of 2.09. Both fields contain background low-redshift quasar candidates selected from the SDSS photometry. In total, 14 new quasars with redshifts up to 2.and i magnitudes between 16.7 and 19.2. are discovered, including 7 within the 2.5° central region of M 31. We briefly discuss the potential applications of these newly discovered bright quasars.

关键词： galaxies individual (M31) -- quasars general -- quasars emission lines

New planetary nebulae in the outskirts of the Andromeda Galaxy discovered with the Guoshoujing Telescope (LAMOST)

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Research in Astronomy and Astrophysics 2010年第7期10卷 599-611页

作者： Hai-Bo Yuan Xiao-Wei liu Zhi-Ying Huo Hui-hua Z{2.g Yong-Heng Zhao Jian-Jun Chen Zhong-Rui Bai Hao-Tong Z{2.g hua-Wei Z{2.g Ruben Garcia-Benito Mao-Sheng xiang Hong-liang Yan Juan-Juan Ren Shi-Wei Sun Yong Z{2.g Ye-Ping li Qi-Shuai Lu You Wang Ji-Jun Ni Hai Wang Department of Astronomy Peking University Beijing 100871 China Kavli Institute for Astronomy and Astrophysics Peking University Beijing 100871 China national astronomical Observatories Chinese Academy of Sciences Beijing 100012 China Department of Astronomy Beijing Normal University Beijing 100875 China Nanjing Institute of astronomical Optics ＆ Technology Chinese Academy of Sciences Nanjing 210042 China

Planetary nebulae （PNe） are good tracers of the stellar populations, chemical composition and dynamics of their host galaxies. This paper reports the discovery of new PNe in the outskirts of the Andromeda Galaxy （M31） with the Guoshoujing Telescope （GSJT, formerly named the Large Sky Area Multi-Object Fiber Spectroscopic Telescope-LAMOST） during its early commissioning phase. In total, 36 candidates selected from SDSS photometry are confirmed in terms of their PN nature, including 17 new discoveries and another 19 previously known emission line objects. Their positions, spectra, radial velocities and m5007 magnitudes are presented. We discuss the potential for detecting more PNe in M 31 with GSJT＇s multi-object spectroscopy and the related app{2.cations in studies of the dynamics and chemistry of M 31 and its assemblage history.

关键词： galaxies individual (M 31) -- planetary nebulae general

Atmospheric and Oceanic Excitations to LOD Change on Quasi-biennial Tune Scales

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chinese Journal of Astronomy and Astrophysics 2006年第6期6卷 759-768页

作者： li-hua Ma De-Chun liao Yan-Ben han national astronomical Observatories Chinese Academy of Sciences Beijing 100012 Shanghai astronomical Observatory Chinese Academy of Sciences Shanghai 200030

We use wavelet transform to study the time series of the Earth＇s rotation rate （length-of-day, LOD）, the axial components of atmospheric angular momentum （AAM） and oceanic angular momentum （OAM） in the period 1962.2.05, and discuss the quasi-biennial oscillations （QBO） of LOD change. The results show that the QBO of LOD change varies remarkably in amp{2.tude and phase. It was weak before 1978, then became much stronger and reached maximum values during the strong El Nino events in around 1983 and 1997. Results from analyzing the axial AAM indicate that the QBO signals in axial AAM are extremely consistent with the QBOs of LOD change. During 1963-2.03, the QBO variance in the axial AAM can explain about 99.0% of that of the LOD, in other words, all QBO signals of LOD change are almost excited by the axial AAM, while the weak QBO signals of the axial OAM are quite different from those of the LOD and the axial AAM in both time-dependent characteristics and magnitudes. The combined effects of the axial AAM and OAM can explain about 99.1% of the variance of QBO in LOD change during this period.

关键词： Earth's variable rotation - atmospheric angular momentum - oceanic angular momentum

Acceleration feedback control (AFC) enhanced by disturbance observation and compensation (DOC) for high precision tracking in telescope systems

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Research in Astronomy and Astrophysics 2016年第8期16卷 51-60页

作者： Qiang Wang hua-xiang Cai Yong-Mei huang liang Ge Tao Tang Yan-Rui Su xiang liu jin-Ying li Dong He Sheng-Ping Du Yu ling Institute of Optics and Electronics Chinese Academy of Sciences Chengdu 610209 China Key Laboratory of Optical Engineering Chinese Academy of Sciences Chengdu 610209 China University of chinese academy of sciences Beijing 100049 China Key Laboratory of Optical Astronomy National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China

Abstract In this paper, a cascade acceleration feedback control （AFC） enhanced by a disturbance observa- tion and compensation （DOC） method is proposed to improve the tracking precision of telescope systems. Telescope systems usually suffer some uncertain disturbances, such as wind load, nonlinear friction and other unknown disturbances. To ensure tracking precision, an acceleration feedback loop which can in- crease the stiffness of such a system is introduced. Moreover, to further improve the tracking precision, we introduce the DOC method which can accurately estimate the disturbance and compensate it. Furthermore, the analysis of tracking accuracy used by this method is proposed. Finally, a few comparative experimental results show that the proposed control method has excellent performance for reducing the tracking error of a telescope system.

关键词： telescopes -- instrumentation control method - instrumentation miscellaneous high angularresolution - instrumentation detector -- control software