Wavelet Analysis of Solar Diameter Measurements Performed at Calern Observatory Astrolabe

Since 1975, a visual program of solar diameter measurement is pursuedat Calern Observatory (France). These observations allowed to put inevidence variations in solar data. Several studies were developed inorder to analyze the data using appropriate me thods (deconvolution ofthe observation window function and least square fits) (Moussaouiet al., 1999). We present in this work a time-frequency studyof the found harmonic terms. It is developed using the wavelettransform. The obtained results are presented and discussed.     

Solar diameter measurements with Calern Observatory astrolabe and atmospheric turbulence effects

In order to deduce significant astrophysical results from solar diameter measurements it is necessary to take an accurate account of instrumental and atmospheric effects. This paper presents a comparison between visual and CCD camera measurements performed by means of the Calern Observatory solar astrolabe during the last 4 years; this allows us to evaluate visual measurements done previously (from 1975 to 1989). Then, a study of atmospheric effects is developed. From CCD measurements, the image quality, expressed by Fried's seeing parameter,r ₀, is estimated and related to the errors occurring in solar diameter measurements. A statistical analysis gives about 0.26 arc sec (or 0.13 arc sec for the semi-diameter) as the lowest value that this error may reach at Calern Observatory. One conclusion of this work is that it is important in the future to have image quality observations, obtained using a dedicated monitor, in order to evaluate and classify the measurements. A survey of the seeing might so lead to improve the precision of the results by weighting each diameter estimation and eventually to schedule the observations.     

Measurements of Atmospheric Extinction at a Ground Level Observatory

In order to determine the atmospheric extinction at Physics Department Astronomical Observatory of the University of Extremadura, located at Badajoz (Spain), several stars were observed during some clear nights of atmospheric stability in the period 1998–2000, at optical wavelengths corresponding to the filters of the Kron-Cousins and Strömgren photometric systems. The determination of the extinction coefficients was made by assuming the Bouguer's law, which was shown to be a good approximation for this study. The results exhibited temporal variations and can be considered to be associated with clean atmospheres at locations of low altitude.     

云台等高仪自控系统和光子计数接收处理终端研制

在等高仪的转轴上安装角检测元件——圆感应同步器和数显表,用微机控制等高仪自动导星定位、自动方位跟踪。定位精度±3～4″,跟踪精度±4″。采用光子计数接收处理终端,使等高仪观测极限星等从原来的7等提高到11等。     

Measurements of atmospheric turbulence parameters at Vainu Bappu Observatory using short-exposure CCD images

We report atmospheric turbulence parameters, namely atmospheric seeing, tilt-anisoplanatic angle(θ_0) and coherence time(Τ_0), measured under various sky conditions, at Vainu Bappu Observatory in Kavalur. Bursts of short exposure images of selected stars were recorded with a high-speed, frame-transfer CCD mounted on the Cassegrain focus of a newly commissioned 1.3 m telescope. The estimated median seeing is ≈ 1.85 " at wavelength of ～ 600 nm, the image motion correlation between different pairs of stars is ～44% for θ0≈ 36" and mean Τ_0 is ≈ 2.4 ms. This work was motivated by the design considerations and expected performance of an adaptive optics system that is currently being planned for the telescope.     

Earth Radioactivity Measurements with a Deep Ocean Anti-neutrino Observatory

We consider the detector size, location, depth, background, and radio-purity required of a mid-Pacific deep-ocean instrument to accomplish the twin goals of making a definitive measurement of the electron anti-neutrino flux due to uranium and thorium decays from Earth’s mantle and core, and of testing the hypothesis for a natural nuclear reactor at the core of Earth. We take the experience with the KamLAND detector in Japan as our baseline for sensitivity and background estimates. We conclude that an instrument adequate to accomplish these tasks should have an exposure of at least 10 kilotonne-years (kT-y), should be placed at least at 4 km depth, may be located close to the Hawaiian Islands (no significant background from them), and should aim for KamLAND radio-purity levels, except for radon where it should be improved by a factor of at least 100. With an exposure of 10 kT-y we should achieve a 25% measurement of the flux of U/Th neutrinos from the mantle plus core. Exposure at multiple ocean locations for testing lateral heterogeneity is possible.     

云南天文台天文新技术实验室工作进展

云南天文台新技术实验室成立至今已走过十几个年头，这些年来为云南天文台的发展作出了很多的贡献。从我国的第一套ＣＣＤ系统到天文遥在观测，不但在天文技术领域有所发展，而且目前拥有一支老中青相结合的相对稳定的队伍。本文主要回顾了新技术室这些年来的主要工作。     

Asteroid mass determination at Nikolaev Observatory

Masses of asteroids are topical for research in ephemerides computations and density evaluations. Details of the dynamical method are given for asteroid mass determinations. Preliminary masses of 13 asteroids, obtained with relative errors less than 50%, are presented from non-weighted least squares. Accuracy improvement of mass values for dynamical computations is evident using contemporary observations of 1999-2006. Statistics of the fitting ephemerides to the observations is also discussed.     

Video observation of meteors at Yunnan Observatory

In the last 20 years, with the development of the CCD and image intensifiers, the use of small flexible video meteor observation systems has gradually increased, with the prospect that one day video observation will replace the visual observation and ordinary photographic observations. In this paper we report on the research and development of the No.1 meteor-comet video camera system of Yunnan Observatory and some preliminary observed results. The system consists of 5 changeable modules; it has a 36° large-field camera dedicated to the observation of meteors, with which a magnitude 6 star can be recorded on a single frame with an accuracy of about 0.2 mag. We also present a comparison of the video camera system with the traditional photographic system, and outline the merits, possible improvements and future development of the video system.     

Measurements of the vertical distribution of ozone by ground-based microwave techniques at the Bordeaux Observatory during the June 1981 intercomparison campaign

Spectra of the ozone emission line at 110.832 GHz were obtained by a ground-based technique using radio microwaves at the Bordeaux Observatory, France, during the Intercomparison Ozone Campaign on 19 and 26 June 1981. From the spectra, it is possible to obtain altitude profiles of the ozone concentration by a model-fitting computation method which is briefly described.The resulting profiles are given, which can be compared with other observations in the same altitude range.     

云南天文台的非太阳天体物理观测研究

简要总结了自１９７９年以来云南天文台在宇宙学、星系物理、行星和彗星物理方面的主要进展。也对相关仪器的研制和选址工作进行了评述。     

Solar research at the Pulkovo Astronomical Observatory

The paper deals with the review of works on solar observations at Abastumani Astrophysical Observatory during the past 12 years. The works accomplished on the basis of patrol observations, with the horizontal solar telescope, small and large coronagraphs, and those based on the data obtained during eclipse observations are discussed separately.     

云南天文台的精密定轨系统

概述了精密定轨轮廓及其重要性,重点介绍了云南天文台的精密定轨系统,包括处理流程、所采用的动力学模型及其参考系的选取,并介绍了残差分析方法,用以剔除"野值"以及分析测站数据质量。运用该精密定轨系统,分析处理了LAGEOS从2004年1月1日到2004年10月26日的全球SLR数据以及AJISAI从2008年5月3日到2009年2月26日全球SLR数据,每3天一个弧段,LAGEOS的测站总RMS不超过3cm,主要集中在1.5cm附近,AJISAI的测站总RMS不超过6cm,主要集中在3.5cm附近,与同期空间研究中心CSR的RMS相当,表明云南天文台用于精密定轨的系统运算结果是可信的。     

Chandra and his students at Yerkes Observatory

S. Chandrasekhar’s interactions with graduate students in his more than a quarter century at Yerkes Observatory are described. His graduate teaching, Ph.D. thesis students, colloquia and colloquium series, and seminar series were all important aspects of this side of his scientific research career. His managing editorship ofThe Astrophysical Journal, his one experience in observational astrophysics, a second paper he wrote describing some of the early observational work at Yerkes Observatory, and a third on “the case for astronomy” are all discussed. A famous myth about one of his courses is corrected, and the circumstances under which the “S. Candlestickmaker” parody was written are recounted. Chandra’s computers, recruited in the Williams Bay community, are mentioned. A complete or nearly complete table of all the thesis students who received their Ph.D. degrees under his supervision, at Yerkes and on the campus in Chicago up through his last one in Astronomy and Astrophysics in 1973, is presented, with references to their published thesis papers.     

从窗口看云南天文台

简要总结了云南天文台２０年来的科研工作及人才培养情况，并对未来的发展提出了设想。