共查询到20条相似文献，搜索用时 141 毫秒
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太阳系外行星探测方法及统计特征 总被引：1，自引：1，他引：0
太阳系外行星的探测和研究在过去十几年取得了重大进展,仅2007年就发现62颗太阳系外行星,随着行星物理学、天体生物学等学科的兴起,必将掀起对太阳系外行星研究的一次浪潮.简要回顾了太阳系外行星研究的发展历史,介绍了探测太阳系外行星的主要方法和手段,并对方法本身的特点展开分析论述,列出了各种方法应用的最新进展.对已发现的270多颗太阳系外行星进行了统计分析,得出了一些预见性的结论. 相似文献
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GPS时间比对数据的归化 总被引：2，自引：1，他引：1
胡锦伦 《中国科学院上海天文台年刊》1995,(16):193-201
根据时间实验室在不同时刻接收的GPS时间比对数据，采用三次样条函数的归化方法，本文给出了UTC 0^h的本地时间尺度与BlockⅠ和BlockⅡ卫星的GPS时间差，这些归化结果与世界上一些时间中心（国际计量局（BIPM）时间部、美国海军天文台（USNO）等）的结果比较表明：当取样时间为1天时，国际时间同步的不确定度优于50ns;SA(Selective Availability）效应的影响减少到50ns以内，因此，这种方法是一种精确的有效的方法。 相似文献
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《天文学报》2016,(5)
天体测量法是探测系外行星一种有效的手段,具有其他探测方法所不具备的独特优势,如可以探测到行星的3维轨道参数及确定行星的质量等,这些将为现有的行星样本提供重要补充.高精度的空间天体测量卫星Gaia(Global Astrometric Interferometer for Astrophysics)在2013年成功发射升空,可以预期未来基于其探测数据,将可能发现大量的长周期类木行星.针对αCentauri A、HD 62509和GJ 876系统,根据Gaia单次天体测量精度生成对应的仿真数据,使用Lomb-Scargle周期谱分析行星轨道周期信号,并采用Markov Chain Monte Carlo(MCMC)算法对行星系统进行轨道反演,得到的结果与行星的初始参数相吻合. 相似文献
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随着空间目标活动和卫星导航系统的增多,观测电离层数据的途径越来越多,探测精度也越来越高.在Kalman滤波的基础上,利用2016年的国际参考电离层(IRI-2016)模型中电离层垂直电子含量(Vertical Total Electron Content, VTEC),结合地基反演得到的VTEC值,利用数据融合算法提高电离层VTEC的近实时反演精度.针对加拿大附近高纬度区域(130°W–150°W, 60°N–70°N)、朝鲜、韩国和日本周边中纬度区域(115°E–135°E, 32.5°N–42.5°N)、洪都拉斯和危地马拉附近低纬度区域(80°W–100°W, 10°N–20°N)进行了观测,比较发现地基反演和数据融合技术得到的电离层VTEC精度都比较高,但是数据融合得到的电离层VTEC在3个区域的精度都明显更好.该算法能够很好地应用在地面基准站数量较多的区域,同时也能应用在地面基准站数量较少或者海洋、沙漠等布设地面基准站不方便的区域,提高电离层VTEC的精度. 相似文献
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随着500 m口径球面射电望远镜(Five-hundred-meter Aperture Spherical radio Telescope, FAST)等大型射电望远镜的建设和使用,脉冲星巡天数据进入PB时代.为解决如此大量高速采样的标量数据挖掘问题,促进新天文现象的发现,提出一种基于无监督聚类的脉冲星候选体筛选方案.该方案采用基于密度层次、划分方法的混合聚类算法,结合MapReduce/Spark并行计算模型和基于滑动窗口的分组策略,进而提高大量候选体信号筛选的效率.通过在脉冲星数据集HTRU2 (High Time Resolution Universe)上的对比实验,结果表明该算法能取得较高的精确度和召回率,分别是0.946和0.905,并且当并行节点足够时,该算法的时间复杂度相比串行执行明显下降.可见,该方法为脉冲星观测大数据的分析挖掘提供一种可行思路. 相似文献
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极移速度的周期分析 总被引：1，自引：0，他引：1
钱昌夏 《中国科学院上海天文台年刊》1995,(16):35-40
本文对瞬时极的移动速度用自回归谱估计的Marple算法进行了周期分析，结果表明，瞬时极的移动速度可能存在着2386.天（6.5天）、1168.9天（3.2年）、321.3天、163.7天、130.1天及92.7天等6个周期，同时计算了极移的振幅和周期，发现极移的速度与极移的振幅正相关，与极移的周期负相关，并且发现厄尔尼诺现象都出现在地极移动周期较短的年份。 相似文献
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自适应光学技术应用于激光测月中大气波前倾斜量的探测与计算 总被引：2，自引：0，他引：2
针对云南天文台1.2米望远镜在激光测月中回波光子数太少的问题，将大气湍流效应考虑到激光测月中，研究了互相关和绝对差分两种跟踪算法的原理，并编写了算法程序，利用太阳数据验证了程序的正确性,给出了根据所采集的月面感兴趣区域的图像数据，用不同方法在不同条件下处理所得的大气波前整体倾斜信号，比较了算法的优劣。 相似文献
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《天文学进展》2004,22(4):364-368
天文学、天文学史离群数据的探测....................................................……张彦霞赵永恒(11)虚拟天文台的科学意义.............................................……张彦霞赵永恒(4,350)仪器与技术激光时间传递技术的进展............................................……李鑫数字滤波技术在射电天文测量中的应用................................……项英应用Al,A的对数周期馈源方案于FAST的可能性探讨 .....................……吴盛殷熊继衷吕善伟张江林徐祥南仁东多波段巡天和LAMOST观测目标. .........……何… 相似文献
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The application of data mining in astronomical surveys,such as the Large Sky Area MultiObject Fiber Spectroscopic Telescope(LAMOST)survey,provides an effective approach to automatically analyze a large amount of complex survey data.Unsupervised clustering could help astronomers find the associations and outliers in a big data set.In this paper,we employ the k-means method to perform clustering for the line index of LAMOST spectra with the powerful software Astro Stat.Implementing the line index approach for analyzing astronomical spectra is an effective way to extract spectral features for low resolution spectra,which can represent the main spectral characteristics of stars.A total of 144 340 line indices for A type stars is analyzed through calculating their intra and inter distances between pairs of stars.For intra distance,we use the definition of Mahalanobis distance to explore the degree of clustering for each class,while for outlier detection,we define a local outlier factor for each spectrum.Astro Stat furnishes a set of visualization tools for illustrating the analysis results.Checking the spectra detected as outliers,we find that most of them are problematic data and only a few correspond to rare astronomical objects.We show two examples of these outliers,a spectrum with abnormal continuum and a spectrum with emission lines.Our work demonstrates that line index clustering is a good method for examining data quality and identifying rare objects. 相似文献
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Fred Lombard Chris Koen Diederick Potgieter 《Monthly notices of the Royal Astronomical Society》2001,325(3):1133-1141
The American Association of Variable Star Observers supplies the astronomical community with a large data base of times of light maxima and minima of Mira (long-period pulsating) stars. Period change studies using these data invariably use either times between maxima, or those between minima. A statistical analysis based on the two-component time series of light curve rise and fall times is developed. The results, which enable one to detect changes in the shapes of light curves, are applied to observations of seven long-period variables. 相似文献
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Chenzhou Cui Dongwei FanYongheng Zhao Ajit KembhaviBoliang He Zihuang CaoJian Li Deoyani Nandrekar 《New Astronomy》2012,17(2):167-174
Although the roles of data centers and computing centers are becoming more and more important, and on-line research is becoming the mainstream for astronomy, individual research based on locally hosted data is still very common. With the increase of personal storage capacity, it is easy to find hundreds to thousands of FITS files in the personal computer of an astrophysicist. Because Flexible Image Transport System (FITS) is a professional data format initiated by astronomers and used mainly in the small community, data management toolkits for FITS files are very few. Astronomers need a powerful tool to help them manage their local astronomical data. Although Virtual Observatory (VO) is a network oriented astronomical research environment, its applications and related technologies provide useful solutions to enhance the management and utilization of astronomical data hosted in an astronomer’s personal computer. FITSManager is such a tool to provide astronomers an efficient management and utilization of their local data, bringing VO to astronomers in a seamless and transparent way. FITSManager provides fruitful functions for FITS file management, like thumbnail, preview, type dependent icons, header keyword indexing and search, collaborated working with other tools and on-line services, and so on. The development of the FITSManager is an effort to fill the gap between management and analysis of astronomical data. 相似文献
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钱神恩 《中国天文和天体物理学报》1995,(1)
本文介绍一种用于天文观测图象数据无信息丢失的现场实时数据压缩方法。在对原始图象数据可压缩性统计分析之后，介绍了一种适合天文观测数据现场实时数据压缩的方法＂基础比特＋溢出比特＂编码方法。讨论了为提高压缩比而采取的各种措施。以ＤＥＮＩＳ项目中现场观测原始数据压缩为例，说明了信息保存型实时数据压缩的实现过程，最后给出了该方法的实验结果，实验表明，本文介绍的数据压缩方法在无任何信息丢失的情况下，可获得接近理论值的数据压缩比。 相似文献
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A.C. Becker 《Astronomische Nachrichten》2008,329(3):280-283
I provide an incomplete inventory of the astronomical variability that will be found by next‐generation time‐domain astronomical surveys. These phenomena span the distance range from near‐Earth satellites to the farthest Gamma Ray Bursts. The surveys that detect these transients will issue alerts to the greater astronomical community; this decision process must be extremely robust to avoid a slew of “false” alerts, and to maintain the community's trust in the surveys. I review the functionality required of both the surveys and the telescope networks that will be following them up, and the role of VOEvents in this process. Finally, I offer some ideas about object and event classification, which will be explored more thoroughly by other articles in these proceedings. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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Vincent Eke 《Monthly notices of the Royal Astronomical Society》2001,324(1):108-118
A speedy pixon algorithm for image reconstruction is described. Two applications of the method to simulated astronomical data sets are also reported. In one case, galaxy clusters are extracted from multiwavelength microwave sky maps using the spectral dependence of the Sunyaev–Zel'dovich effect to distinguish them from the microwave background fluctuations and the instrumental noise. The second example involves the recovery of a sharply peaked emission profile, such as might be produced by a galaxy cluster observed in X-rays. These simulations show the ability of the technique both to detect sources in low signal-to-noise ratio data and to deconvolve a telescope beam in order to recover the internal structure of a source. 相似文献
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Jones Hancock Lasenby Davies Gutiérrez Rocha Watson & Rebolo 《Monthly notices of the Royal Astronomical Society》1998,294(4):582-594
The complete set of data from the Tenerife 10-GHz (8° FWHM) twin-horn, drift scan experiment is described. These data are affected by both long-term atmospheric baseline drifts and short-term noise. A new maximum entropy procedure, utilizing the time invariance and spatial continuity of the astronomical signal, is used to achieve a clean separation of these effects from the astronomical signal, and to deconvolve the effects of the beam-switching. We use a fully positive/negative algorithm to produce two-dimensional maps of the intrinsic sky fluctuations. Known discrete sources and Galactic features are identified in the deconvolved map. The data from the 10-GHz experiment, after baseline subtraction with MEM, are then analysed using conventional techniques, and new constraints on Galactic emission are made. 相似文献
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With the fast increase in the resolution of astronomical images, the question of how to process and transfer such large images has become a key issue in astronomy. We propose a new real-time compression and fast reconstruction algorithm for astronomical images based on compressive sensing techniques. We first reconstruct the original signal with fewer measurements, according to its compressibility. Then,based on the characteristics of astronomical images, we apply Daubechies orthogonal wavelets to obtain a sparse representation. A matrix representing a random Fourier ensemble is used to obtain a sparse representation in a lower dimensional space. For reconstructing the image, we propose a novel minimum total variation with block adaptive sensing to balance the accuracy and computation time. Our experimental results show that the proposed algorithm can efficiently reconstruct colorful astronomical images with high resolution and improve the applicability of compressed sensing. 相似文献