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1.
We present the improved solar radio spectrograph of the University of Athens operating at the Thermopylae Satellite Telecommunication Station. Observations now cover the frequency range from 20 to 650 MHz. The spectrograph has a 7-meter moving parabola fed by a log-periodic antenna for 100–650 MHz and a stationary inverted V fat dipole antenna for the 20–100 MHz range. Two receivers are operating in parallel, one swept frequency for the whole range (10 spectrums/sec, 630 channels/spectrum) and one acousto-optical receiver for the range 270 to 450 MHz (100 spectrums/sec, 128 channels/spectrum). The data acquisition system consists of two PCs (equipped with 12 bit, 225 ksamples/sec ADC, one for each receiver). Sensitivity is about 3 SFU and 30 SFU in the 20–100 MHz and 100–650 MHz range respectively. The daily operation is fully automated: receiving universal time from a GPS, pointing the antenna to the sun, system calibration, starting and stopping the observations at preset times, data acquisition, and archiving on DVD. We can also control the whole system through modem or Internet. The instrument can be used either by itself or in conjunction with other instruments to study the onset and evolution of solar radio bursts and associated interplanetary phenomena.  相似文献   

2.
本文介绍了日食射电观测及其资料预处理的基本方法。其中包括日食观测点的选址、观测前的准备、日食观测和食后资料的预处理等。通过资料预处理 ,可得到归一化天线温度和斜率食变曲线 ,为研究日面亮度温度分布和射电源参数等基本物理量提供基本数据和资料  相似文献   

3.
A new radiospectrograph at Culgoora   总被引：1，自引：0，他引：1  
IPS Radio and Space Services (IPS) commissioned a new radiospectrograph for solar observations in May 1992. The instrument operates over a frequency range from 18 MHz to 1.8 GHz and samples every three seconds. Digital data acquisition permits a variety of analysis procedures that were not previously possible. The operation of the new instrument is briefly described and some example radiospectrograms are presented.  相似文献   

4.
Fine structure observations of the frequency spectrum of the S-component in the solar radio emission are described. Measurements were carried out in August 1976 and August 1977 using a 22 m parabolic antenna and a radiospectrograph operating over the frequency range 5.0 to 7.0 GHz, with the resolution 60 MHz. Measurement techniques are described. Fine structures (150–800 MHz) as great as 20% of the local source radiation level were observed in radio emission spectra of a number of these sources. The spectrum structures observed were changed in the process of active region development.  相似文献   

5.
Maroulis  D.  Dumas  G.  Caroubalos  C.  Bougeret  J. L.  Moussas  X.  Alissandrakis  C.  Patavalis  N. 《Solar physics》1997,172(1-2):353-360
We present the new digital solar radio spectrograph located at the Thermopyles station, Greece, operated by the University of Athens. Observations cover the range from 110 to 600 MHz, using a 7-m parabolic antenna. The reception system uses two techniques in parallel: sweep frequency and multi-channel, the latter being based on the Acousto-Optical technique. The data acquisition system is based on two subsystems, a Sun Sparc-5 workstation and a front end based on a VME Motorola system. The two subsystems are connected through the Ethernet and are operated using the VxWorks real-time package. The daily operation is completely automated: pointing of the antenna to the sun, starting and stopping the observations at pre-set times, acquiring data, compressing data by silence suppression in real time, and archiving the data on a routine manner on DAT tapes. Apart from its usual function, this instrument will be used in conjunction with other instruments, including the Nançay decameter array and the low frequency radio receivers on the Wind spacecraft.  相似文献   

6.
The hardware and software for the observation of millisecond bursts with the Siberian solar radio telescope (SSRT) at 5.2 cm is described. The multiprocessing computer and data acquisition system records 180 analog signals from the SSRT multichannel receiver every 7 milliseconds. The recorded information opens the opportunity to study the position, structure, and other characteristics of solar burst sources with high temporal and spatial resolution. Examples of the observations are presented and briefly discussed in order to illustrate the overall performance of the system.  相似文献   

7.
The solar observational facilities at ARIES (erstwhile U.P. State Observatory, UPSO), Nainital, began in the sixties with the acquisition of two moderate sized (25 cm, f/66 off-axis Skew Cassegrain and 15 cm, f/15 refractor) telescopes. Both these systems receive sunlight through a 45 cm and 25 cm coelostat respectively. The backend instruments to these systems comprised of a single pass grating spectrograph for spectroscopic study of the Sun and a Bernhard-HalleHα filter, coupled with a Robot recorder camera for solar patrolling inHα respectively. With the advancement in solar observing techniques with high temporal and spatial resolution inHα and other wavelengths, it became inevitable to acquire sophisticated instrumentation for data acquisition. In view of that, the above facilities were upgraded, owing to which the conventional photographic techniques were replaced by the CCD camera systems attached with two 15 cm, f/15 Coude refractor telescopes. These CCD systems include the Peltier cooled CCD camera and photometrics PXL high speed modular CCD camera which provide high temporal and spatial resolution of ∼ 25 ms and ∼ 1.3 arcsec respectively.  相似文献   

8.
A general analysis of phased array noise properties and measurements, applied to one square meter tiles of the Thousand Element Array (THEA), has resulted in a procedure to define the noise budget for a THEA-tile (Woestenburg and Dijkstra, 2003). The THEA system temperature includes LNA and receiver noise, antenna connecting loss, noise coupling between antenna elements and other possible contributions. This paper discusses the various noise contributions to the THEA system temperature and identifies the areas where improvement can be realized. We will present better understanding of the individual noise contributions using measurements and analysis of single antenna/receiver elements. An improved design for a 1-m2 Low Noise Tile (LNT) will be discussed and optimized low noise performance for the LNT is presented. We will also give future perspectives of the noise performance for such tiles, in relation to the requirements for SKA in the 1 GHz frequency range.  相似文献   

9.
This article describes the observations of a type III radio burst observed at 103 MHz simultaneously by the two radio telescopes situated at Rajkot (22.3°N, 70.7°E) and Thaltej (23°N, 72.4°E). This event occurred on September 30, 1993 at about 0430 UT and lasted for only half a minute. The event consisted of several sharp spikes in a group. The rise and fall time of these are comparable, however the peaks of individual spikes varied by a factor of four. The comparison of these observations with the data of solar radio spectrograph HiRAS indicates that this was a metric radio burst giving highest emission at about 103 MHz.  相似文献   

10.
The observations of the solar radio emission on September 11, 2001, with the RATAN-600 radio telescope (southern sector) at four centimeter wavelengths (1.92, 2.24, 2.74, and 3.21 cm) revealed synchronous brightenings in solar radio sources. These were identified on the solar photosphere with active regions that were spaced up to ～106 km apart (AR 9608 and AR 9616). We discuss manifestations of the possible mechanisms of synchronous brightenings in solar sources in a narrow microwave spectral band. The significant linear correlation (ρc = 0.84–0.92) between the relative fluxes of AR 9610 and AR 9608 at 1.92 and 2.24 cm and the significant linear correlation (ρc = 0.65–0.84) between the relative fluxes of AR 9606 and AR 9608 at 3.21 cm in a two-hour interval of observations are indicative of the interconnection between these active regions not only during flares and bursts, but also in the periods of their absence. This confirms the existence of a large-scale temporal component in the dynamics of the radio flux variations for these active regions. We found a difference between the temporal variations of the radio emission from the halo and the solar radio sources under consideration. The times of increase in the total solar soft X-ray (0.5–4.0 Å, 1.0–8.0 Å; GOES 8, GOES 10) flux are shown to coincide with the times of increase in the fluxes from the solar radio sources at short centimeter wavelengths.  相似文献   

11.
介绍了70～700MHz低频太阳射电频谱仪的科学目标和技术方案,给出了11m 网状抛物面天线、接收系统、数字频谱终端的技术指标.并对系统的整机噪声系数、灵敏度、最小可测流量密度、LNA输入端的噪声功率进行了估计.系统频谱分辨率优于0.2MHz,时间分辨率最高可达2 ms.  相似文献   

12.
Decameter wavelength radio emission is finely structured in solar bursts. For their research it is very important to use a sufficient sensitivity of antenna systems. In this paper we study an influence of the radiotelescope‐antenna effective area on the results of decameter solar radio observations. For this purpose we compared the solar bursts received by the array of 720 ground‐based dipoles and the single dipole of the radiotelescope UTR‐2. It is shown that a larger effective area of the ground‐based antenna allows us to measure a weaker solar emission and to distinguish a fine structure of strong solar events. This feature has been also verified by simultaneous ground‐ and space‐based observations in the overlapping frequency range (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

13.
根据不同的发射波模以及偏振态（偏振度与偏振方向）的快速时变特征,对1993年10月2日07：44：34-07：44：52：99UT期间的太阳射电事件进行了证认,认为这是一个由两群、总数约为40个尖峰（spike）结构组成的罕见的宽带事件,它的总带宽＞300MHz、相对带宽■5％．根据它们在2．545GHZ,2．645GHZ;2．695GHZ和2B40GHZ上的流量资料,首次对一些spike结构作了谱分析．发现spike结构谱的峰值频率,第一群呈现为随时间由高频向低频漂移的倾向,第二群基本上位于2．695GHZ上．Spike谱的这些观测特征,可定性地用非热电子束流平均能量的时变特性来解释．对于第二群具有相同峰值频率的spike辐射,可能来自同一电子回旋脉泽不稳定区域．  相似文献   

14.
脉冲星脉冲到达时间观测系统建立在２５ｍ射电天线的１８ｃｍ波段上,消色散采用了２ｘ１２８ｘ２．５ＭＨｚ多通过滤波器和数字化器,数据采集系统由ＰＣ机完成．１９９９年５月至６月间建立了基于常温接收机的到达时间观测系统．观测到的最弱源的平均流量密度为４ｍＪｙ．  相似文献   

15.
In the dynamic spectrograms of the 60-channel solar radiospectrograph at Dwingeloo coherent groups of Type I bursts have been selected. At 243 MHz the positions of the bursts were measured. Within many groups the bursts showed a systematic angular displacement with time. Movements with apparent velocities up to 15000 km s–1 have been observed. The burst positions have been obtained with a two-element interferometer. A special data reduction method used the amplitude variation of the Type I bursts as a parameter for selection against the background radiation.  相似文献   

16.
太阳总辐照是指在地球大气层顶接收到的太阳总辐射照度,也叫"太阳常数",但它实际上并非常数。太阳总辐照随波长的分布即为太阳分光辐照。太阳辐照变化的研究,对理解太阳表面及内部活动的物理过程、机制,研究地球大气、日地关系,解决人类面临的全球气候变暖的挑战等,都具有重要意义。首先简单介绍了太阳辐照,回顾了太阳辐照的空间观测;接着介绍了观测数据的并合,以及对合成数据的一些研究;然后讨论了太阳辐照变化的原因,简述了太阳总辐照的重构及其在气候研究上的一些应用,并进行必要的评论;最后对未来的研究方向提出了一些看法。  相似文献   

17.
随着天线口径增大、频率升高,日照热对其性能的影响愈发严重.针对待建的新疆110 m大口径全可动射电望远镜,建立其热分析有限元模型,研究天线在夏至日不同太阳时刻的温度场分布特性.结果如下:一天中,主反射面的最高温度可达42.86℃,出现在14时,同时刻撑腿的温度也达到峰值,为41.74℃.背架水平分区温差在5时、18时、19.5时均超过1℃,会对天线指向性能产生较大影响.夜间天线结构温度分布亦不均匀,俯仰结构的温差明显高于其他构件,最大温差为6.42℃,通过数值模拟与试验相结合的方法,证明了构件的壁厚差异是导致结构夜间温差较大的主要原因.  相似文献   

18.
We report here a study of various solar activity phenomena occurring in both north and south hemispheres of the Sun during solar cycles 8–23. In the study we have used sunspot data for the period 1832–1976, flare index data for the period 1936-1993, Hα flare data 1993–1998 and solar active prominences data for the period 1957–1998. Earlier Verma reported long-term cyclic period in N-S asymmetry and also that the N-S asymmetry of solar activity phenomena during solar cycles 21, 22, 23 and 24 will be south dominated and the N-S asymmetry will shift to north hemisphere in solar cycle 25. The present study shows that the N-S asymmetry during solar cycles 22 and 23 are southern dominated as suggested by Verma.  相似文献   

19.
The analysis of observations of the eclipse on August 1, 2008, at wavelengths of 10.5 and 12 cm demonstrated that, in the epoch of deep minimum between the 23rd and 24th cycles of solar activity, the radio radius of the solar disk in the equatorial direction was 120 × 103 km larger than the radio radius in the polar direction. In this case, the brightness temperature of the polar region turned out to be of the order of (35–37) × 103 K and corresponded to the radiation emission from upper layers of the chromosphere from an altitude of about 11 × 103 km. At the heliolatitude <25° beyond the visible disk at a distance of about 70 × 103 km from the photosphere an increased radio brightness of up to 100 × 103 K was observed, which testifies to the increased electron density in the equatorial zone of the corona at the complete absence of groups of spots on the solar disk.  相似文献   

20.
We study the temporal behavior of the power spectra for Galactic cosmic-ray fluctuations during the last two solar cycles. We use the 5-min data for 1980–2002 corrected for the barometric effect from two widely separated high-latitude cosmic-ray stations, Tixie Bay and Oulu. The cosmicray fluctuation spectrum is shown to be subjected to a regular long-term modulation with a period of about 11 years in phase with the solar cycle, in accordance with the variations in the inertial part of the turbulence spectrum for the interplanetary magnetic field. Based on independent measurements, we confirm the previously detected cosmic-ray fluctuation power enhancement at the maximum of the 11-year solar cycle and its subsequent decrease at minimum solar activity using new, more extensive data sets. We reach the conclusion about the establishment of a new cosmic-ray modulation phenomenon that has not been described previously in scientific literature.  相似文献   

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