米波分米波太阳射电频谱观测研究

本文介绍了云南天文台米波分米波两个波段射电频谱仪的性能指标及可能的观测研究选题。     

日食的射电观测

日食为射电天文提供了一维高空间分辨率太阳射电观测机会,日食射电观测在太阳射电物理的发展上起过重要的作用,文中对日食射电观测的若干重要因素作了介绍和分析,日食射电观测在我国太阳射电天文台发展上也起了重要作用,文中简要介绍了在我国组织观测的１９５８年,１９６８年,１９８０年及１９８７年太阳射电日食观测及其主要结果。     

太阳射电高时间分辨率观测中的干扰问题

本文对太阳射电高时间分辨率观测中的一些干扰问题作了初步分析,并提出了区分太阳射电精细结构事件与雷达干扰的相应办法。     

太阳射电观测中蝴蝶斑的一种消除方法

本试图根据蝴蝶斑的分布特征，采用平滑滤波的方法，消除太阳射电高时间分辨率观测资料中，由于某种干扰引起的蝴蝶斑，从而达到在这种资料中提取有用太阳信息的目的。     

四波段太阳射电快速同步观测系统的试观测及其意义

本文主要介绍该系统(波长21.1cm、15cm、10.6cm和7.5cm)的试观测资料及其观测的目的。     

太阳射电频谱仪超高时间分辨率观测的新结果

国家天文台分米波太阳射电频谱仪用新的观测模式获得太阳射电频谱的一些新的观测现象。新的观测模式频率在1．1—1．34GHz范围，时间分辨率是1．25ms；正常的观测模式下频率在1．1—2．06GHz范围，时间分辨率是5ms。在两种模式下频率分辨率为4MHz。发现窄带Ⅲ型爆发（“blips”）斑马纹（Zebra）和纤维结构（Fiber）中的超精细结构和一些新的精细结构。这些新的结果有助于深入理解在太阳耀斑期间低日冕中能量的释放和转移，也为拟建中的太阳射电频谱日像仪提出了新的要求。     

云南天文台太阳射电研究进展

回顾了自１９７９年以来云南天文台太阳射电天文仪器、技术和方法以及研究方面的进展。     

On Solar Intermediate Drift Radio Bursts at Decimeter and Meter Wavelength

Fiber – or intermediate drift – bursts are a continuum fine structure in some complex solar radio events. We present the analysis of such bursts in the X17 flare on 28 Oct. 2003. Based on the whistler wave model of fiber bursts we derive the 3D magnetic field structures that carry the radio sources in different stages of the event and obtain insight into the energy release evolution in the main flare phase, the related paths of nonthermal particle propagation in the corona, and the involved magnetic field structures. Additionally, we test the whistler wave model of fiber bursts for the meter and the decimeter wave range. Radio spectral data (Astrophysikalisches Institut Potsdam, Astronomical Observatory Ond?ejov) show a continuum with fibers for ≈?6 min during the main flare phase. Radio imaging data (Nançay Radio Heliograph) yield source centroid positions of the fibers at three frequencies in the spectrometer band. We compare the radio positions with the potential coronal magnetic field extrapolated from SOHO/MDI data. Given the detected source site configuration and evolution, and the change of the fiber burst frequency range with time, we can also extract those coronal flux tubes where the high-frequency fiber bursts are situated even without decimeter imaging data. To this aim we use a kinetic simulation of whistler wave growth in sample flux tubes modeled by selected potential field lines and a barometric density model. The whistler wave model of fiber bursts accurately explains the observations on 28 Oct. 2003. A laterally extended system of low coronal loops is found to guide the whistler waves. It connects several neighboring active regions including the flaring AR 10486. For varying source sites the fiber bursts are emitted at the fundamental mode of the plasma frequency over the whole range (1200?–?300 MHz). The present event can be understood without assuming two different generation mechanisms for meter and decimeter wave fiber bursts. It gives new insight into particle acceleration and propagation in the low flare and post-CME corona.     

Solar Partial N－burst

We present a new sub-class of type Ⅲ solar radio burst at the high frequencies around 6.0 GHz. In addition to a descending and an ascending branch on the dynamic spectrum, it has an inverted morphology different from the simpletype U-burst. We call it “partial N-burst“ because it is interpreted as the known N-burst minus its first branch. The partial N-burst presented here was detected among a reverse slope type Ⅲ (RS-Ⅲ) burst group prior to the type V solar radio continuum and was simultaneously recorded by two spectrometers at the National Astronomical Observatories, Chinese Academy of Sciences (NAOC, 5.20-7.60 GHz) and at Purple Mountain Observatory (PMO, 4.50-7.50 GHz) on 1999 August 25.After the N-burst and M-burst, the partial N-burst is a third piece of evidence for a magnetic mirror effect in solar radio observation, when the same electron is reflected at a pinched foot of a flare loop.     

21cm波段太阳爆发中的精细结构

本文简要介绍了云南天文台新建立的21cm波段快速(不中断采样)记录系统,及使用该系统观测到的快速尖峰事件。系统得到的太阳分米波段爆发中不同时间尺度的精细结构与Stu-rroch等提出的太阳耀斑中能量释放的模式相一致。     

一个新型分米波太阳微耀斑现象的观测分析

本文介绍一组短分米波（1．42GHz）太阳微耀斑的射电和光学辐射特征，它们包含53个叠加在连续辐射背景上的射电快速精细结构（FFS），即准周期快速脉冲链（称微耀斑），它们的形态相似，强度大约在150－200sfu范围内，其寿命（半功率宽）大多为15－50ms，有18个分离的双峰结构，该事件产生的7646活动区中出现两处新浮现的几个小黑子，呈现复杂极性，可能存在多重交叉小磁流环多次重联的复杂状况．本文定性地讨论了其产生机制，支持电流环爆炸性聚合模型的理论。     

日冕分米波射电甚短周期脉动的观测证据

利用国家天文台云南天文台“分米波(700—1500MHz)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2001年6月24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29、40和100毫秒)的脉动，后者是一个射电大爆发，在2840MHz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29—40毫秒)的脉动现象，甚短周期脉动可能是归因于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调制，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。     

Array Signal Processing for Radio Astronomy

Radio astronomy forms an interesting application area for array signal processing techniques. Current synthesis imaging telescopes consist of a small number of identical dishes, which track a fixed patch in the sky and produce estimates of the time-varying spatial covariance matrix. The observations sometimes are distorted by interference, e.g., from radio, TV, radar or satellite transmissions. We describe some of the tools that array signal processing offers to filter out the interference, based on eigenvalue decompositions and factor analysis, which is a more general technique applicable to partially calibrated arrays. We consider detection of interference, spatial filtering techniques using projections, and discuss how a reference antenna pointed at the interferer can improve the performance. We also consider image formation and its relation to beamforming.     

Some Observed Results of Solar Radio Spectrometer at 4.5—7.5GHz

A new instrument of broadband solar radio spectrometer working at waveband 4.5-7.5GHz was developed at Purple Mountain Observatory for Solar Maximum 23. Some new results of spectral observation have been obtained since August 1999.Two typical type Ⅲμbursts with rich fine structures are presented and some interesting features discussed.     

太阳大气磁精细结构的射电探讨

太阳大气磁场的研究对于太阳大气物理及太阳活动研究是十分重要的。目前探测光球以外的日够以球，过渡区磁场的几乎唯一办法，是在紧密联系其他频说段取得的信息基础上使用射电观测。根据在微波，米波段有关辐射机制和传播过程，介绍了推导磁场讯息的基本射电方法。     

Scaling-laws of Radio Spike Bursts and Their Constraints on New Solar Radio Telescopestwo

Radio observation is one of important methods in solar physics and space science. Sometimes, it is almost the sole approach to observe the physical processes such as the acceleration, emission, and propagation of non-thermal energetic particles, etc. So far, more than 100 solar radio telescopes have been built in the world, including solar radiometers, dynamic spectrometers, and radioheliographs. Some of them have been closed after the fulfillment of their primary scientific objectives, or for their malfunctions, and thus replaced by other advanced instruments. At the same time, based on some new technologies and scientific ideas, various kinds of new and much more complicated solar radio telescopes are being constructed by solar radio astronomers and space scientists, such as the American E-OVSA and the solar radio observing system under the framework of Chinese Meridian Project II, etc. When we plan to develop a new solar radio telescope, it is crucial to design the most suitable technical parameters, e.g., the observing frequency range and bandwidth, temporal resolution, frequency resolution, spatial resolution, polarization degree, and dynamic range. Then, how do we select a rational set of these parameters? The long-term observation and study revealed that a large strong solar radio burst is frequently composed of a series of small bursts with different time scales. Among them, the radio spike burst is the smallest one with the shortest lifetime, the narrowest bandwidth, and the smallest source region. Solar radio spikes are considered to be related to a single magnetic energy release process, and can be regarded as an elementary burst in solar flares. It is a basic requirement for the new solar radio telescope to observe and discriminate these solar radio spike bursts, even though the temporal and spatial scales of radio spike bursts actually vary with the observing frequency. This paper presents the scaling laws of the lifetime and bandwidth of solar radio spike bursts with respect to the observing frequency, which provide some constraints for the new solar radio telescopes, and help us to select the rational telescope parameters. Besides, we propose a spectrum-image combination mode as the best observation mode for the next-generation solar radio telescopes with high temporal, spectral, and spatial resolutions, which may have an important significance for revealing the physical essence of the various non-thermal processes in violent solar eruptions.