共查询到20条相似文献，搜索用时 62 毫秒
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VLBI标准接口是近年来在VLBI技术中诞生的一个新概念,它旨在解决多年来各VLBI数据传输系统不兼容的问题．该文阐述了VLBI数据传输系统的发展历史,包括传统的记录／回放系统和新兴的网络数据传输两方面的内容;说明了VLBI标准接口的作用和意义;并分别介绍了VLBI标准接口规范3方面的内容:VLBI标准接口件规范(VSI-H)、VLBI标准接口软件规范(VSI-S)和VLBI标准接口网络规范(VSI-E)． 相似文献
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利用美国宇航局(NASA)在1999年的VLBI全球解(glb1123)中关于上海VLBI站与国际上13个VLBI站的基线长变化率高精度测定结果,以及日本鹿岛Kashima和Kashima 34两VLBI站分别与国际VLBI站间的相应结果,基于最近的国际地球参考架ITRF97,估计得到了上海VLBI站和日本鹿岛两VLBI站相对于板块稳定区的地壳垂直形变率分别为-1.91±0.56 mm/yr、-3.72±0.74 mm/yr和-8.81±0.84mm/yr,表明上海VLBI站存在每年近2毫米的下降,讨论并证实日本鹿岛两VLBI站的地壳垂直形变速率是不一致的;基于不同板块运动模型的欧拉旋转矢量,估计得到了上述3站的水平形变速率;还估计给出了太平洋板块中部的形变率结果. 相似文献
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对Mark5B监控系统软件的设计思想、软件功能、通讯机制等几个方面作了介绍。Mark5B记录系统是当今世界VLBI观测台站中广泛使用的最为先进的记录系统之一,也是VLBI终端系统的重要组成部分。研制Mark5B监控系统软件的主要目的是进一步提高VLBI终端记录系统的可靠性,保障VLBI联测数据有效和高质量。该软件是在Qt开发环境下采用signals/slots的安全类型机制,并在Qt creator IDE上设计图形界面,完成数据采集和网络通信工作。Mark5B监控系统不仅适用于VLBI天体物理测量观测、VLBI测地观测,而且适用于中国VLBI网(The Chinese VLBI Network,CVN)联测。 相似文献
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《天文和天体物理学研究(英文版)》2020,(6)
In order to measure the Universal Time(UT1) in real time,National Time Service Center(NTSC)has built a VGOS-like(VLBI Global Observing System) broadband VLBI network,which includes three13-m radio telescopes located in Jilin,Sanya and Kashi,and a data analysis center in Xi'an.Each station is equipped with a highly stable hydrogen atomic clock and a self-developed VLBI backend,and is colocated with two GPS receivers.This VGOS-like VLBI network may play an important role in improving the Chinese broadband VLBI technology and making valuable contributions to domestic VLBI measurements of UT1.In this paper,we introduce the specifications of this VLBI network,and present the UT1 measurements at C-band conducted in 2018 using the Jilin-Kashi baseline of this network.The comparisons between our UT1 estimates and those provided by IERS suggest that the NTSC VLBI network is capable to determine UT1 accurate at the level of 58.8 μs. 相似文献
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《天文学报》2016,(6)
甚长基线干涉测量(VLBI,Very Long Baseline Interferometry)能够提高深空探测器测定轨的精度,目前应用于深空探测中的多为差分VLBI技术(?VLBI).差分VLBI相关相位中存在时间间隔,把不同时间段的相位无整周模糊度地连接起来能清晰地反映卫星运动轨迹,有助于提高卫星的测定轨精度和开展行星无线电科学研究.同时,VLBI相时延因其超高的精度有广泛应用,但解算条件苛刻.基于此,首先利用两个频点的差分相位与单频点相位变化趋势一致的思想,研究了一种新方法连接差分VLBI单频点的相位;然后提出一种利用窄带宽(1 MHz)中的两个频点相位解算相时延的方法,并用嫦娥三号(CE3)着陆器的数据做了实际解算和验证;最后给出了仅利用数天VLBI相时延对着陆器进行定位的方法,得到的结果为(44.1239°N,19.5106°W),和事后基于美国月球侦察轨道器(LRO)窄角相机(NAC)影像数据的定位结果(44.12189°N,19.51129°W)相比,差异为百米左右,验证了仅利用VLBI相时延也能进行着陆器定位的有效性. 相似文献
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Ru-Rong Chen Hai-Yan Zhang Cheng-Jin Jin Zhi-Shen Gao Yan Zhu Kai Zhu Peng Jiang You-Ling Yue Ji-Guang Lu Bo Zhang Wu Jiang Ren-Jie Zhu Shao-Guang Guo Bo Xia Rong-Bing Zhao FAST Collaboration 《天文和天体物理学研究(英文版)》2020,(5):165-170
The Five-hundred-meter Aperture Spherical radio Telescope(FAST)is the largest single-dish radio telescope in the world,and is now being commissioned after the first light in September 2016.Very long baseline interferometry(VLBI)is among the key science topics according to the original design.The FAST VLBI system has been established,and the first VLBI fringe has been successfully obtained.FAST will significantly improve the sensitivity of the existing VLBI networks in the future,and some science projects in need of high sensitivity will benefit from its participation. 相似文献
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Library for Baseband (lbb)是一个自研的用于读取解析甚长基线干涉测量(Very Long Baseline Interferometry, VLBI)基带数据的工具库,主要用于VLBI观测中对终端基带数据的读取、解析及输出结果分析.该软件库通过对基带数据的自动判断,自动实现读取不同数据格式的功能,并提供了各种各样的API (Application Programming Interface)功能供用户调用.目前lbb软件库已经成功应用在了探月工程VLBI测轨任务中的硬件相关处理机配置项和测地VLBI观测数据的预处理.文章详细介绍了lbb软件库的设计、功能及用法. 相似文献
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VLBI观测表明,TeV伽马射线Blazar(耀变体)的喷流运动视速度远小于MeV/GeV伽马射线Blazar,然而TeV伽马射线辐射流量的快速变化却要求这些Blazar的相对论喷流速度与MeV/GeV Blazar的相当.对于这一矛盾,目前有多种解释.为了检验这些模型,我们收集了VLBI对Blazar喷流运动的监测数据,样本包括86个FSRQs(平谱射电类星体)、22个BL Lac天体,共108个Blazar;从统计上研究了,该样本中各Blazar最大视速度喷流节点的位置与射电光度相关关系.结果表明,Blazar最大视速度喷流节点的位置与射电光度有较强的相关关系,随着Blazar射电光度的减小,喷流中最大视速度VLBI节点的位置到VLBI核的距离逐渐变小.这意味着,TeV伽马源(低光度Blazar)的喷流减速区距离VLBI核较近,喷流从高能辐射区到VLBI可分辨尺度已经减速,支持减速喷流模型对TeV伽马射线Blazar上述矛盾的解释. 相似文献
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针对采样返回任务中多探测器精密短弧定轨问题,研究了甚长基线干涉测量(Very Long Baseline Interferometry,VLBI)技术在两探测器间的交替观测模式、2π模糊度解算方法和数据差分处理方法,给出了星载信标的设计原则和方案。利用日本SELENE探月卫星的两个小卫星R-star和V-star的同波束VLBI相关相位生成了交替VLBI相位观测量,对其进行了差分处理求解差分时延,然后利用差分时延和测速测距数据进行定轨计算。对差分时延的分析表明,交替VLBI差分群时延RMS值为46 mm,测量精度与同波束VLBI差分群时延相当;交替VLBI差分相时延RMS值为1.6 mm,测量精度与同波束VLBI差分相时延相当。定轨结果表明,交替VLBI在进行多探测器的短弧定轨时能达到同波束VLBI相当的精度。 相似文献
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介绍了活动星系核 (AGN)的VLBI观测的新近展 ,特别关注其中心结构和低光度的活动星系核。主要目的是强调VLBI观测在该领域的重要性。 相似文献
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The High Energy Stereoscopic System (H.E.S.S.) is a system of Imaging Atmospheric Cherenkov Telescopes (IACTs) located in the Khomas Highland in Namibia. It measures cosmic gamma rays of very high energies (VHE; >100 GeV) using the Earth’s atmosphere as a calorimeter. The H.E.S.S. Array entered Phase II in September 2012 with the inauguration of a fifth telescope that is larger and more complex than the other four. This paper will give an overview of the current H.E.S.S. central data acquisition (DAQ) system with particular emphasis on the upgrades made to integrate the fifth telescope into the array. At first, the various requirements for the central DAQ are discussed then the general design principles employed to fulfil these requirements are described. Finally, the performance, stability and reliability of the H.E.S.S. central DAQ are presented. One of the major accomplishments is that less than 0.8% of observation time has been lost due to central DAQ problems since 2009. 相似文献
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Mathieu de Naurois 《Astrophysics and Space Science》2007,309(1-4):277-284
Recent observations of the binary system LS 5039 with the High Energy Stereoscopic System (H.E.S.S.) revealed that its Very
High Energy (VHE) γ-ray emission is modulated at the 3.9 days orbital period of the system. The bulk of the emission is largely confined to half
of the orbit, peaking around the inferior conjunction epoch of the compact object. The flux modulation provides the first
indication of γ-ray absorption by pair production on the intense stellar photon field. This implies that the production region size must
be not significantly greater than the gamma-gamma photosphere size (∼1 AU), thus excluding the large scale collimated outflows
or jets (extending out to ∼1000 AU). A hardening of the spectrum is also observed at the same epoch between 0.2 and a few
TeV which is unexpected under a pure absorption scenario and could rather arise from variation with phase in the maximum electron
energy and/or the dominant VHE γ-ray production mechanism. This first-time observation of modulated γ-ray emission allows precise tests of the acceleration and emission models in binary systems.
Mathieu de Naurois for the H.E.S.S. Collaboration. 相似文献
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A new method of total ozone retrieval from i.r. satellite data(NOAA6) is presented. It uses ozone transmittance as a predictor of total ozone. Ozone transmittance at 9.6 μm(TR) is deduced from radiance at 9.6 μm(R9), surface temperature (TS) measured at 11 μm, and ozone mean temperature (TE) estimated from several channels (among them 9.6 μm) by the radiative transfer equation : R9 = B(TS) × TR + (1?TR) × B(TE) where B is the Planck function.A statistical analysis of the retrieved ozone field and a comparison with ground based measurements show that the S.E. is less than 5% for the considered data set. 相似文献
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D.R. Bates 《Planetary and Space Science》1975,23(7):1127