对数周期偶极子天线的电特性分析

正在发展中的云南天文中０．５ＧＨｚ－１．５ＧＨｚ快速射电频谱分析仪的接收天线部分是计划在现有十米口径抛物面天线的焦点上安装两付互相垂直的对数周期偶极子天线作为馈源。本文介绍了设计一个ＦＯＲＴＲＡＮ语言程序对对数周期偶极子天线电特性进行分析的过程它可以在整个工作频段范围内计算出任意频率点上一副和周期偶极子天线两个主平面内的方向图、波瓣宽度、增益和输入阻抗，并把结果以数据文件的形式记录下来，结合     

对数周期偶极子天线的设计,制造和测试

文中所作的主要工作是为云南天文台十数抛物面设计、制造一付好的对数周期偶极子天线作馈源。天线理论上的许多成就都与数子计算机有关的。在文中，我们充分利用了计算机的功能来设计天线，分析天线特性，并从测量所得的所有数据文件中计算机的参数。     

对数周期偶极子天线的设计、制造和测试

文中所作的主要工作是为云南天文台十米抛物面设计、制造一付好的对数周期偶极子天线（ＬＰＤＡ）作馈源。工作有：（１）设计一对交叉的ＬＰ－ＤＡ；（２）分析ＬＰＤＡ特性；（３）估算抛物面的电特性；（４）讨论线极化向园极化转换的问题；（５）天线测量。ＬＰＤＡ的测量结果比较满意。该天线的方向图、平均输入阻抗、三分贝和十分贝波瓣宽度都在从０．５－１．５ＧＨｚ的频率范围内比较一致和稳定，变化很小。天线理论上的许多成就都是与数子计算机有关的。在文中，我们充分利用了计算机的功能来设计天线，分析天线特性，并从测量所得的所有数据文件中计算天线的参数。所编ＦＯＲＴＲＡＮ程序使这一切工作变得容易。最后，我们还讨论了用功率合成器实现线极化向园极化转换的各种情况     

一个含有丰富快速精细结构的射电大爆发

本文对１９９０年７月３０日云南天文台四波段（１．４２ＧＨｚ、２．００ＧＨｚ、２．８４ＧＨｚ和４．００ＧＨｚ）太阳射电高时间分辨率同步观测系统［１，２］所观测到的太阳射电大爆发进行了分析，对在１．４２ＧＨｚ、２．００ＧＨｚ、２．８４ＧＨｚ三个波段上观测到的大量尖峰辐射（ｍｓ—ｓｐｉｋｅｓ）作了关于寿命和强度的统计，最后，针对本次爆发中的ｍｓ—ｓｐｉｋｅｓ的特点做了一些讨论。     

一次特大微波IV型爆发事件的分析研究

云南天文台快速采样射电望远镜（１．４２ＧＨｚ，２．８４ＧＨｚ，４．００ＧＨｚ）于１９８８年１２月１６日观测到一次特大微波ＩＶ型爆发。爆发从世界时０８＾ｈ３１＾ｍ结束。在７０分钟的持续期内，爆发出现了五个主峰段，呈现出１２．５分钟的长周期振荡和１．２分钟的短周期振荡。其中两个频率上出现了丰富的快速精细结构。根据爆发源区的扭斜磁场位形，本文提出振荡是ＭＨＤ调制磁流管的磁场强度产生的，爆发是高能电子在磁     

单天线双馈源的研制

本文主要介绍了云南天文台单天线双馈源(λ15厘米,λ21厘米)的结构原理,设计指标及使用结果。     

一个含有丰富快速精细结构的射电大爆发

本文对１９９０年７月３０日云南天文台四波段太阳射电高时间分辨率同步观测系统＾「１，２」所观测到的太阳射电大爆发进行了分析，对在１．４２ＧＨｚ，２．００ＧＨｚ，２．８４ＧＨｚ三个波段上观测到的大量尖峰辐射作了关于寿命和强度的统计，最后，针对本次爆发中的ｍｓ－ｓｐｉｋｅｓ的特点做了一些讨论。     

微波Ⅲ型爆发的一些初步研究

云南天文台“四波段（１．４２ＧＨｚ,２．１３ＧＨｚ,２．８４ＧＨｚ和４．２６ＧＨｚ）太阳射电高时间同步观测系统”在１９９０．１￣１９９４．１期间,观测到５个具有短时标漂移结构的射电爆发事件,也就是微波Ⅲ型爆发。本文从中选取较典型的１９９１年３月１３日事件,对Ⅲ型爆发的时间轮廓（持续时间,衰减时间）作了分析,并与米波,分米波和微波段其它观测结果作了一些比较,以求对长厘米￣短分米波段（微波低端）Ⅲ型爆     

微波Ⅲ型爆发的一些初步研究

云南天文台“四波段（１．４２ＧＨｚ,２．１３ＧＨｚ,２．８４ＧＨｚ和４．２６ＧＨｚ）太阳射电高时间同步观测系统”在１９９０．１～１９９４．１期间,观测到５个具有短时标漂移结构的射电爆发事件,也就是微波Ⅲ型爆发。本文从中选取较典型的１９９１年３月１３日事件,对Ⅲ型爆发的时间轮廓（持续时间,衰减时间）作了分析,并与米波,分米波和微波段其它观测结果作了一些比较,以求对长厘米～短分米波段（微波低端）Ⅲ型爆发的时间轮廓的特征有一个初步的了解,最后对爆发的物理参数作了估计。     

1988年12月16日微波大爆发的研究

１９８８年１２月１６日世纪时０８ｈ３１ｍｉｎ至０９ｈ４１ｍｉｎ，云南天文台ＰｈｏｅｎｉｘＩ日冕射电频谱仪（１．４２ＧＨｚ，２．８４ＧＨｚ，４．００ＧＨｚ）收到一个罕见的微波Ⅳ型大爆发，爆发从米波Ⅳ型一直延伸到微波Ⅳ型，持续时间长，爆发强度大，爆发型别复杂。前后出现了五个主峰段，呈出现１．２ｍｉｎ和１．２５ｍｉｎ的短周期的长周期振荡。在其中的两个频段上叠加有丰富的Ｓｉｋｅ辐射，概括爆发源区的扭斜磁场     

数字图象压缩方法在天文上应用的研究及实验

本文研究了数字图象压缩的方法、分类和原理以及该技术在天文领域应用的必要性。针对天文观测的特点和需要，经过分析比较，提出了天文图象压缩的可行性方案。通过应用计算机编程、压缩实验得到相应结果。文中对天文数字图象分别进行了以下压缩方法实验：无失真压缩中的哈夫曼编码和位平面编码；限失真压缩中的离散余弦变换编码及混合编码等。其压缩比分别可达到２—４．５（无失真压缩）和１０—３０（限失真压缩）。图像压缩所需时间随使用的计算机而异。文中详细列出各种压缩方法的实验结果。     

Erratum: Comprehensive studies of solar activity on the CORONAS-F satellite [<Emphasis Type="Italic">Astronomy letters</Emphasis> 28, 401–410 (2002)]

The first results of comprehensive CORONAS-F observations of solar activity are presented. The CORONAS-F instrumentation and principal scientific objectives are briefly described and examples of the first results of data reduction are given. This article was republished due to two color figures (nos. 4 and 5) missed in the original translation. Our apologies to the authors and the readers of the journal. The online version of the original article can be found at     

Modeling the Star Population of Resolved Galaxies

A program is developed for determining the history of star-forming galaxies based on the use of two- or multicolor photometry of the resolved stars in a given galaxy. We create a library of synthetic color-magnitude diagrams from theoretical stellar isochrones, taking the initial mass function, distance to the galaxy, internal and external absorption, and photometric errors into account. The resulting synthetic diagrams are combined linearly and compared quantitatively with photometric data for stars in a galaxy in order to determine star formation rates as a function of age and metallicity. This program is tested in detail under different conditions using artificial color-magnitude diagrams. Special attention is given to the limiting case when only the brightest stars of a galaxy can be seen in the color-magnitude diagram and the number of resolved stars is at most a few hundred. This limiting case corresponds to a large fraction of the nearby galaxies at distances of 3-5 Mpc observed by large ground based telescopes and the Hubble Space Telescope.     

Recent observations of high-degree solar p-mode oscillations at the Kitt Peak National Observatory

A brief summary is given of a program which is currently being carried out with the McMath telescope of the Kitt Peak National Observatory in order to study high-degree (l ≳ 150) solar p-mode oscillations. This program uses a 244 × 248 pixel CID camera and the main spectrograph of the McMath telescope to obtain velocity-time maps of the oscillations which can be converted into two-dimensional (k _h - ω) power spectra of the oscillations. Several different regions of the solar spectrum have been used in order to study the oscillations at different elevations in the solar atmosphere. The program concentrates on eastward- and westward-propagating sectoral harmonic waves so that measurements can be made of the absolute rotational velocities of the solar photospheric and shallow sub-photospheric layers. Some preliminary results from this program are now available. First, we have been unable to confirm the existence of a radial gradient in the equatorial rotational velocity as was previously suggested. Second, we have indeed been able to confirm the presence of p-mode waves in the solar chromosphere as was first suggested by Rhodes et al. (1977). Third, we have been able to demonstrate differences in photospheric and chromospheric power spectra.

     

Orion: A 1–5 Micron Focal Plane for the 21st Century

The Orion program is a project to develop a 2K × 2K infrared focal plane using InSb p-on-n diodes for detectors. It is the natural follow-up to the successful Aladdin 1K × 1K program started in the early 90's. The work is being done at the Raytheon Infrared Operations Division (RIO, previously known as the Santa Barbara Research Center) by many of the same people who created the Aladdin focal plane. The design is very similar to the successful Aladdin design with the addition of reference pixels, whole array readout (no quadrants), two-adjacent-side buttability, and a packaging design that includes going directly to the ultimate focal plane size of 4K × 4K. So far we have successfully made a limited number of hybrid modules with InSb detectors. In this paper we will describe the design features and test data taken from some of these devices. This revised version was published online in July 2006 with corrections to the Cover Date.     

激变变星及相关天体的H_α与近红外电离钙三重线的光谱分析

给出了1997年4月15日至17日在北京天文台用2．16m望远镜卡焦光谱仪观测获得的6颗激变变星（ABBoo;UXUMa,TCrBAHHer,ZCam和V426Oph）及3颗相关天体（UMa3,EGUMa和Leo3）的CCD光谱,并同时拍摄了5颗晚型星（3Dra,Vir,Leo,34Boo和36Corn）的CCD光谱,作为晚型星参考谱．测量了观测样本星的Hα和近红外CaII的三重线（8498,8542和8662）的等值宽度（EW）,谱线半极大全宽（FWHM）和现向速度（Vr）,并分析了这些星的活动性．     

The Planck On-the-Flight Forecaster (POFF)

The Planck On-the-Flight Forecaster (POFF) is a tool to predict when a position in the sky will be within a selected angular distance from any instrument receiver direction in the Planck satellite taking into consideration its programmed observational plan. The tool has been developed in the framework of the Planck LFI Core Team activities, but it is now used by the whole Planck collaboration.In this paper we describe the tool and its applications to plan observations of point sources with other instruments which are expected to increase the scientific importance of Planck data, once they are publicly available. Collecting simultaneous multi-frequency data, like those that can be planned with the POFF, will aid the investigation of variability in point sources and also allow the reconstruction of point source spectral energy distributions over wide frequency range, thus minimizing the effect of variability itself.POFF is a combination of IDL routines which combine the publicly available information about the Planck scanning strategy with the focal plane shape to identify if a given (list of) position(s) could be observed by the satellite at a given frequency and/or by selected receivers in a given time range. The output can be displayed with any reasonable desired time resolution and with various sorting options.The code is not a Planck product, but has been validated with the Planck LFI pipeline, by searching for sources in the first satellite datasets. It has been implemented as one of the general tools of the LFI Data Processing Center. The code format and its large number of options make the program flexible and suitable for many applications, facilitating fast results.POFF is currently successfully used to plan activities within the Planck collaboration, including observations with several ground-based facilities, and is also available to the larger scientific community.     

Kepler discretization in regular celestial mechanics

In this paper, a special extrapolation method for the numerical integration of perturbed Kepler problems (given in KS-formulation) is worked out and analyzed in detail. The underlying so-called Kepler discretization isexact for the pure (elliptic) Kepler motion. A numerically stable realization is presented together with a backward error analysis: this analysis shows that the effect of the arising rounding errors can be regarded as a small perturbation inferior to the physical perturbation. For test purposes, a well-known example describing the motion of an artificial Earth satellite in an equator plane subject to the oblateness perturbation is used to demonstrate the efficiency of the new extrapolation method.Proceedings of the Sixth Conference on Mathematical Methods in Celestial Mechanics held at Oberwolfach (West Germany) from 14 to 19 August, 1978.     

Low-Energy Anomalous Cosmic Rays in the Ecliptic Plane: 1-5 AU

Anomalous cosmic-ray (ACR) oxygen (O) fluxes in the energy range 0.5-5.0 MeV nucleon-1 were measured in the ecliptic plane at 1 and 5 AU in 1997 and 1998. Using measurements from essentially identical instruments on the Advanced Composition Explorer (ACE) and Ulysses spacecraft, we were able to monitor the decrease with time of the ACR O fluxes in the inner heliosphere during the onset of solar cycle 23. The data obtained from three time intervals that are relatively undisturbed by solar activity during this period show that the e-folding time is approximately 140+/-40 days for the disappearance of 2-5 MeV nucleon-1 ACR oxygen from the ecliptic plane at 5 AU.