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《天文研究与技术》2016,(3)
明安图射电频谱日像仪(Mingantu Ultrawide Sp Ectral Radioheliograph,MUSER)是新一代具有高时间、高空间、高频率分辨率的太阳专用射电望远镜,采用综合孔径原理成像,所以幅度和相位是决定最后成图质量的关键因素。天线的相位方向图会影响日像仪输出的幅度和相位,根据日像仪的馈源设计和综合孔径原理,针对明安图射电频谱日像仪天线数目多,且为户外环境,根据天文观测须经常测试天线性能的特点,给出了基于相关结果测量日像仪天线相位方向图的方法,该方法可以直接通过日像仪的相关输出结果高效准确地得到天线的相位方向图。对MUSER-I天线的相位方向图进行了测量和分析,同时分析了天线相位方向图对日像仪成像的影响,为得到高质量的太阳图像提供了参考和保障。 相似文献
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射频干扰是射电天文观测设备无法回避的问题。国家天文台(内蒙古)明安图观测基地多台各具特色的射电观测设备、各类电磁辐射源及其传播路径共同组成了复杂的电磁环境。现有超宽带高分辨太阳射电成像观测设备——明安图射电频谱日像仪,以及即将建设的子午二期工程的太阳行星际监测系统,包括米波-十米波射电日像仪、行星际闪烁望远镜和超宽带射电频谱仪等,全部频率覆盖1 MHz～15 GHz,观测结果用于太阳物理、空间天气监测和预报的关键问题研究,也对电磁环境提出了更高要求。介绍了明安图观测基地的观测设备及其地理环境,给出了方位频率功率谱、立体方向图、时间频率功率谱等射频干扰的初步监测结果,讨论了射频干扰预防、消减及射频干扰自监测方案。 相似文献
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中国新一代射电频谱日像仪——明安图射电频谱日像仪以高时间、高空间、高频率分辨率工作在0.4 GHz~15 GHz,为太阳爆发活动初始能量释放区的物理过程、太阳电子加速等研究开辟了新的窗口。高性能、高质量太阳成像算法是日像仪数据处理流水线至关重要的研究内容。参考法国墨东天文台太阳干涉阵的数据处理方法,系统讨论分析了多尺度洁化(Multi-Scale CLEAN)算法,给出了适用于日像仪的多尺度洁化算法参数,并重点讨论了算法的图形处理器并行实现。实验结果表明,改进的多尺度洁化在算法效率上比基于图形处理器实现的H9gbom CLEAN提高了近3倍,有效提高了整个数据处理流水线的性能。 相似文献
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明安图射电频谱日像仪每天产生海量观测数据,传统的关系型数据库存储和管理这些数据时,面临着读写延迟高、性能和容量扩展能力有限以及可用性弱等诸多问题。针对这些问题,开展了基于No SQL的海量数据存储与检索应用研究。首先,详细分析了明安图射电频谱日像仪的数据特点、存储需要以及面临的问题;然后,对明安图射电频谱日像仪进行数据建模,给出了明安图射电频谱日像仪的列式非关系型数据模型,同时提出了元数据和数据在No SQL中的同步存储方法,解决了二者的一致性问题,在此基础上实现了基于Cassandra的海量天文数据存储管理系统(MBDMS);最后通过实验验证了系统存储与检索的高效性、扩展性以及可行性。实验结果表明,MBDMS可以很好地满足数据管理的需要,是解决当前数据存储问题的一种有效方案。 相似文献
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明安图射电频谱日像仪(Mingantu Spectral Radioheliograph, MUSER)能够在0.4--15GHz超宽频带内实现高时间、高空间、高频率分辨率的太阳射电成像. 而射电亮温度是描述太阳物理过程的一个重要的参数, 在研究不同射电辐射机制、太阳磁场以及太阳爆发过程中非热粒子加速等问题上有着非常重要的作用, 因此必须对MUSER观测的图像进行亮温度定标. 将介绍一种适用于射电日像仪图像强度定标的方法. 太阳射电图像中包含着太阳圆盘的结构信息, 利用射电日像仪短基线的可视度函数拟合第一类贝塞尔函数, 可以得到图像中宁静太阳圆盘的射电半径和强度, 再利用瑞利-金斯定律和每天的太阳射电流量可以计算得到每天图像的定标因子$G_c$, 从而实现对MUSER图像强度的定标. 将该方法应用到MUSER的实际观测数据中, 包括宁静太阳和有太阳射电爆发等不同的情况, $G_c$的误差基本不超过10%, 得到的宁静太阳亮温度与其他宁静太阳的结果具有较高的相关性, 表明了此方法的可行性和有效性. 相似文献
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叙述了太阳射电天文和太阳物理上作出过杰出贡献的几个射电日像仪的概况及其进步与发展,并简述了未来射电日像仪可以完成的科学目标以及应具有的特点,以期为在２１世纪我国实现“一颗空间Ｘ射线卫星、一座红外太阳塔和一台射电像仪”的宏伟构想提供研制依据。 相似文献
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We present new results of heliographic observations of quiet‐Sun radio emission fulfilled by the UTR‐2 radio telescope. The solar corona investigations have been made close to the last solar minimum (Cycle 23) in the late August and early September of 2010 by means of the two‐dimensional heliograph within 16.5–33 MHz. Moreover, the UTR‐2 radio telescope was used also as an 1‐D heliograph for one‐dimensional scanning of the Sun at the beginning of September 2010 as well as in short‐time observational campaigns in April and August of 2012. The average values of integral flux density of the undisturbed Sun continuum emission at different frequencies have been found. Using the data, we have determined the spectral index of quiet‐Sun radio emission in the range 16.5–200 MHz. It is equal to –2.1±0.1. The brightness distribution maps of outer solar corona at frequencies 20.0 MHz and 26.0 MHz have been obtained. The angular sizes of radio Sun were estimated. It is found that the solar corona at these frequencies is stretched‐out along equatorial direction. The coefficient of corona ellipticity varies slightly during above period. Its mean magnitudes are equal to ≈ 0.75 and ≈ 0.73 at 20.0 MHz and 26.0 MHz, respectively. The presented results for continuum emission of solar corona conform with being ones at higher frequencies. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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MSRT的太阳观测能力 总被引：2，自引：0，他引：2
密云米波综合孔径射电望远镜（ ＭＳＲＴ） 是一架同时具有高空间分辨率和高时间分辨率,高灵敏度的大型设备,工作频率在２３２ ＭＨｚ。使用该望远镜能得到太阳爆发的空间分布及其随时间变化的丰富信息,所得数据将填补我国具有空间分辨率的太阳射电数据的空白。在国际太阳活动监测中,由于地理位置原因,也是其它同类设备不可取代的。可以期待在第２３ 周太阳峰年的观测与研究中,得到新的有意义的数据和研究成果 相似文献
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To locate two-dimensional positions of the solar decametric radio bursts a heliograph was developed on the basis of the UTR-2 radiotelescope (Khar'kov) operated in the range 10–26 MHz. The beamwidth of the heliograph rapid-scanning pencil-beam is 25 arc min at 25 MHz, and its field of view is about 3.5° (E-W) × 2.0° (N-S). The instrument yields rapidly forty records of the radio brightness of all (8 × 5) elementary parts (each 25 arc min in diameter) of the investigated sky area during every period of 1/4 s. Both coordinates of a burst center are measured with an accuracy 5 arc min. The bandwidth of the receiving system is 10 kHz. The heliograph operates in conjunction with a radiospectrograph connected to the output of a N-S arm of the UTR-2 array. The data observations with the UTR-2 correspond only to one linear polarized component.The ionospheric distortion of the test records of the radio source Cassiopeia-A that occurred sometimes is illustrated.First results of 25 MHz observations of the solar radio storm in August, 1976 with the heliograph are presented here. This storm is accompanied by the compact sunspot group travelling all over the optical disk. The type III and stria bursts were predominant during the storm. On the given day the scattering regions of their apparent centers were overlapped and the sizes of these regions were usually not more than 5 arc min. On some days there occurred additional burst sources displaced in position from the persistent storm region. It was found out that, as a rule, 25 MHz stria-bursts from the type IIIb chain coincided in position with the following type III burst at the same frequency. The difference of the daily averaged coordinates of both stria and type III bursts was considerably smaller than the mean diameter of their sources.The radial distance of the 25 MHz storm region from the solar center was calculated by using the three methods. The storm height was estimated as 1.8R
from the rotation rate close to the central meridian of the storm center. Definite association of the spots with the storm near the limb allowed to determine the average value 2.1R
for the height. The limb measurements give the mean height of 2.3R
.The center-to-limb variation of the storm source height is a known fact in the meter-wavelength range. This is the evidence of the propagation effects in the solar corona being essential to interpret the results of the radio source location. 相似文献
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L. Győri 《Solar physics》2010,267(2):445-461
Accurate heliographic coordinates of objects on the Sun have to be known in several fields of solar physics. One of the factors
that affect the accuracy of the measurements of the heliographic coordinates is the accuracy of the orientation of a solar
image. In this paper the well-known drift method for determining the orientation of the solar image is applied to data taken
with a solar telescope equipped with a CCD camera. The factors that influence the accuracy of the method are systematically
discussed, and the necessary corrections are determined. These factors are as follows: the trajectory of the center of the
solar disk on the CCD with the telescope drive turned off, the astronomical refraction, the change of the declination of the
Sun, and the optical distortion of the telescope. The method can be used on any solar telescope that is equipped with a CCD
camera and is capable of taking solar full-disk images. As an example to illustrate the method and its application, the orientation
of solar images taken with the Gyula heliograph is determined. As a byproduct, a new method to determine the optical distortion
of a solar telescope is proposed. 相似文献
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总结了近期用射电频谱仪（高时间和高频谱分辨）和野边山射电日像仪（高空间分辨）以及国内外其它空间和地面设备分析日冕磁场和重联的系列工作。主要结论可归纳为：1）在Dulk等人（1982）的近似下自恰计算射电爆发源区磁场的平行和垂直分量，并首次得到该磁场在日面的两雏分布。2）为了考虑非热电子低能截止的影响，必须采用更严格的回旋同步辐射理论来计算。结果表明：低能截止和日冕磁场对计算有明显的影响，而其它参数（包括背景温度、密度、高能截止和辐射方向）的影响均可忽略。因此，对低能截止和日冕磁场必须联立求解。3）射电爆发中的精细结构可能反映了射电爆发源比较靠近粒子加速（磁场重联）的区域，利用高时间和高频率分辨的频谱仪和高空间分辨的日像仪联合分析，可以确定精细结构的源区位置，从而确定粒子加速（磁场重联）的准确时间和地点。 相似文献
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本文列举了云南天文台四波段太阳射电实测中得到的几种干扰实例及确认的太阳快速信号，在认识到太阳射电和干扰信号十分相似的基础上，探讨如何识别真伪信号问题。 相似文献
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Tan Bao-lin Cheng Jun Tan Cheng-ming Kou Hong-xiang 《Chinese Astronomy and Astrophysics》2019,43(1):59-74
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. 相似文献
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Adolfo L. Méndez Berhondo Ana K. Díaz Rodríguez P. Zlobec Lupe Cuendias Pérez 《Astrophysics and Space Science》2013,346(2):301-306
The dynamic characteristics of solar metric radio bursts with intermediate drifting patterns (fiber bursts) as they evolve at fixed frequency are examined. The data were recorded using the radio polarimeter of the Trieste Astronomical Observatory. The aim is to determine if the underlying process can be described as a deterministic chaos. Correlation dimensions and Hurst exponent are estimated showing deterministic chaotic system of low dimension. 相似文献
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The ratios of radio to optical diameter of the solar disc at 10.7 and 3 cm wavelengths are examined. The radio observations are daily east–west scans of the solar disc, made over the period 1975–1992, which includes almost two complete solar cycles. We find that the apparent disc diameter is slightly greater at solar minimum than it is at solar maximum, suggesting that the radio diameter varies over the cycle. Moreover, the ratio is smaller at 3 cm wavelength than it is at 10.7 cm, at both solar maximum and minimum. 相似文献