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星像的位置和亮度等信息对天文研究和空间导航具有基础意义。人们常常需要快速匹配从密集星场CCD图像中提取的信息来获取与星表中对应的信息(如位置、光度等),因此开发出了多种星像匹配算法。重点比较了两种最新的星像匹配算法:i)基于向量的方法;ii)基于径向和环向特征的方法。通过对云南天文台1m望远镜观测的CCD图像进行实际匹配,结果表明基于向量的方法更优,它是一种快速的、接近常数时间的匹配算法。 相似文献
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基于BATC巡天组近十年的观测值班记录,统计了兴隆观测站可观测时间随月份的变化,结果表明平均每年大约有195个可观测夜(约1986小时),其中大约有87个观测夜(约918小时)用来巡天,约有18个观测夜用来测光.另外还统计了兴隆观测站施密特望远镜十年来北极天区的观测图像中星像的半高全宽(FWHM)随月份的变化,结果表明一年内平均星像的半高全宽约为2.3像元(老CCD)或2.2像元(新CCD).一般来说,夏季的星像要好于冬季,这与刘颖(Liu)等人2003年[1]的结果基本一致. 相似文献
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南极高原拥有独特的天文观测优势,为了对南极中山站夜天文观测条件进行实测研究,中国科学院云南天文台专门研制了一套具有耐低温、自动除雪除霜等适应南极气候特征的全自动全天信息采集系统,该系统可以提供实时的全天云量、天光背景和全天图像,并将信息推送到网页实时显示。介绍了系统的研制及为适应南极气候进行的耐低温实验,统计分析了中山站2016~2017年的全天信息数据,结果显示,中山站2016和2017年的可观测时间为772.21 h和437.38 h,可观测夜数为93 d和51 d,天光背景最大真实值为22.05 Mag/arcsec 2,年平均气温为-10.6℃,最高气温19.1℃,最低气温为-44℃,2016年平均相对湿度为55.2%。 相似文献
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《天文研究与技术》2020,(4)
全天相机已广泛应用在气象、天文等领域,在监测云量、夜天光、流星时,需要准确掌握相机的姿态参数,特别是在安装和运维中造成的偏差。旨在开发一套基于虚拟天文馆的像场测量方法,通过比较参考恒星的虚拟坐标及其像点的实测坐标,高精度地测量相机的姿态参数。使用中国科学院云南天文台安置于四川无名山观测站的全天相机,分析了2016年至2017年获得的4组全天图像,采集了容量分别约为10、50、200的恒星样本,通过Stellarium虚拟天文馆获得了恒星的地平坐标,对全天相机像场的天顶位置、测者子午线方向等基本参数进行了精确的测量。主要结果为:(1)开发了一种基于虚拟天文馆计算恒星地平坐标功能的测量方法,使姿态测量建立在容量较大的参考恒星上,该方法准确度高,对设备配置的依赖性低,具有较强的可移植性;(2)采用网格法对图像天顶的定位达到了亚像素的精度,有望满足高精度定位监测的需要;(3)全天相机姿态精度的首要指标是光轴的竖直性,光轴偏离天顶对投影的轴对称造成不可忽略的影响;(4)维护作业对圆形像场几何参数的改变甚微,但可能改变指向和旋转角,并需要重新测量;(5)生成了符合制图惯例的可视化产品,为监测数据的深入分析奠定了基础。 相似文献
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This is a crucial time in the history of astronomy with major all-sky surveying work being carried out in all spectral bands, as well as in astrometry. The results of this activity are advancing all fields of astrophysical research, from the investigation of exo-planetary systems to the study of the chemical evolution of the Universe. Full sky surveys are available from the radio domain to X-ray wavelengths but not in the ultraviolet range (UV). While large UV missions are currently under discussion within the astrophysical community and at the major Space Agencies, the efficient use of resources requires preparatory work that can fill the UV surveying gap. This article summarizes the research and on-going activities in this field. 相似文献
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R. A. Burenin 《Astronomy Letters》2017,43(8):507-515
We present a catalogue of galaxy clusters detected in the Planck all-sky Compton parameter maps and identified using data from the WISE and SDSS surveys. The catalogue comprises about 3000 clusters in the SDSS fields. We expect the completeness of this catalogue to be high for clusters with masses larger than M 500 ≈ 3 × 1014 M ⊙, located at redshifts z < 0.7. At redshifts above z ≈ 0.4, the catalogue contains approximately an order of magnitude more clusters than the 2nd Planck Catalogue of Sunyaev-Zeldovich sources in the same fields of the sky. This catalogue can be used for identification of massive galaxy clusters in future large cluster surveys, such as the SRG/eROSITA all-sky X-ray survey. 相似文献
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Marcelo Armengot Nestor Sánchez Javier López-Santiago Ana Inés Gómez de Castro 《Astrophysics and Space Science》2014,354(1):113-119
Large sky surveys are providing a huge amount of information for studies of the interstellar medium, the galactic structure or the cosmic web. Setting into a common frame information coming from different wavelengths, over large fields of view, is needed for this kind of research. GALEX is the only nearly all-sky survey at ultraviolet wavelengths and contains fundamental information for all types of studies. GALEX field of view is circular embedded in a squared matrix of 3840×3840 pixels. This fact makes it hard to get GALEX images properly overlapped with the existing astronomical tools such as Aladin or Montage. We developed our own software for this purpose. In this article, we describe this software and makes it available to the community. 相似文献
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For four selected fields in the Catalogue of IRAS Faint Sources we have calculated the two-point correlation function of the galaxies and the correlation fractal dimension. The results show that the galaxies in all the fields are clustered on small angular scales. On larger scales, the distribution can be well expressed by a multi-level fractal. On still larger scales, possible typical scales can be detected using un-normalized pair counts. The average results for the four fields are consistent with previous results for the all-sky IRAS point sources and other sky surveys. 相似文献
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目前利用VLBIMK3系统确定的延迟测量的精度约为30ps,在这样的精度下,改善计算延迟的理论模型,考虑各种微扰改正(包含30ps量级)是非常重要的。在VLBI天休测量和测地计算的各种软件中,至今尚未计及射电源结构对延迟的影响。本文利用两子源模型对源结构延迟的大小及随时间的变化进行了计算,讨论了源结构延迟对VLBI天测和测地参数的影响,指出:(1)除对某些VLBI天测的射电源作长期的监测与研究,给出它们的双频综合图外,对大多数源可采用简单的两子源模型;(2)源结构对延迟的影响主要依赖于基线相对于源形态的主要特征的空间投影;(3)源结构延迟对天测和测地参数的影响达厘米和亚毫角秒量级。 相似文献
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Angélica de Oliveira-Costa Max Tegmark B. M. Gaensler Justin Jonas T. L. Landecker Patricia Reich 《Monthly notices of the Royal Astronomical Society》2008,388(1):247-260
Understanding diffuse Galactic radio emission is interesting both in its own right and for minimizing foreground contamination of cosmological measurements. cosmic microwave background experiments have focused on frequencies ≳10 GHz, whereas 21-cm tomography of the high-redshift universe will mainly focus on ≲0.2 GHz, for which less is currently known about Galactic emission. Motivated by this, we present a global sky model derived from all publicly available total power large-area radio surveys, digitized with optical character recognition when necessary and compiled into a uniform format, as well as the new Villa Elisa data extending the 1.42-GHz map to the entire sky. We quantify statistical and systematic uncertainties in these surveys by comparing them with various global multifrequency model fits. We find that a principal component based model with only three components can fit the 11 most accurate data sets (at 10, 22, 45 and 408 MHz and 1.42, 2.326, 23, 33, 41, 61, 94 GHz) to an accuracy around 1–10 per cent depending on frequency and sky region. Both our data compilation and our software returning a predicted all-sky map at any frequency from 10 MHz to 100 GHz are publicly available at http://space.mit.edu/home/angelica/gsm . 相似文献
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J. M. Trigo-Rodríguez A. J. Castro-Tirado J. Llorca J. Fabregat V. J. Martínez V. Reglero M. Jelínek P. Kubánek T. Mateo A. de Ugarte Postigo 《Earth, Moon, and Planets》2004,95(1-4):553-567
We have developed an all-sky charge coupled devices (CCD) automatic system for detecting meteors and fireballs that will be
operative in four stations in Spain during 2005. The cameras were developed following the BOOTES-1 prototype installed at
the El Arenosillo Observatory in 2002, which is based on a CCD detector of 4096 × 4096 pixels with a fish-eye lens that provides
an all-sky image with enough resolution to make accurate astrometric measurements. Since late 2004, a couple of cameras at
two of the four stations operate for 30 s in alternate exposures, allowing 100% time coverage. The stellar limiting magnitude
of the images is +10 in the zenith, and +8 below ~ 65° of zenithal angle. As a result, the images provide enough comparison
stars to make astrometric measurements of faint meteors and fireballs with an accuracy of ~ 2°arcminutes. Using this prototype,
four automatic all-sky CCD stations have been developed, two in Andalusia and two in the Valencian Community, to start full
operation of the Spanish Fireball Network. In addition to all-sky coverage, we are developing a fireball spectroscopy program
using medium field lenses with additional CCD cameras. Here we present the first images obtained from the El Arenosillo and
La Mayora stations in Andalusia during their first months of activity. The detection of the Jan 27, 2003 superbolide of ±
17 ± 1 absolute magnitude that overflew Algeria and Morocco is an example of the detection capability of our prototype. 相似文献
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Earth and space-based NEO survey simulations: prospects for achieving the spaceguard goal 总被引:1,自引:0,他引:1
We have used an improved model of the orbit and absolute magnitude distribution of Near Earth Objects (NEOs) to simulate the performance of asteroid surveys. Our results support general conclusions of previous studies using preliminary Near Earth Asteroid (NEA) orbit and magnitude distributions and suggest that meeting the Spaceguard Goal of 90% completion for Near Earth Objects (NEOs) greater than 1 km diameter by 2008 is impossible given contemporary surveying capabilities.The NEO model was derived from NEO detections by the Spacewatch Project. For this paper we developed a simulator for the Catalina Sky Survey (CSS) for which we had a complete pointing history and NEO detection efficiency. The good match between the output of the simulator and the actual CSS performance gives confidence that both the NEO model and simulator are correct. Then, in order to determine if existing surveys can meet the Spaceguard Goal, we developed a simulator to mimic the LINEAR survey, for which detailed performance characteristics were unavailable. This simulator serendipitously provided an estimate for the currently undiscovered population of NEOs upon which we base all our estimates of time to 90% completion. We also developed a set of idealized NEO surveys in order to constrain the best possible survey performance in contrast to more realistic systems.A 100% efficient, all-sky, every night survey, subject only to the constraints of detection above a specified air mass and when the Sun is 18° below the horizon provides a benchmark from which to examine the effect of imposing more restrictions and the efficacy of some simple survey strategies. Such a survey must have a limiting V-magnitude of 20.1 ± 0.2 to meet the Spaceguard Goal.More realistic surveys, limited by latitude, the galaxy, minimum rates of NEO motion, etc., require fainter limiting magnitudes to reach the same completion. Our most realistic simulations, which have been normalized to the performance of the LINEAR detector system’s operation in the period 1999-2000, indicate that it would take them another 33 ± 5 years to reach 90% completeness for the larger asteroids (?1 km diameter). They would need to immediately increase the limiting magnitude to about 24 in order to meet the Spaceguard Goal.The simulations suggest that there may be little need for distributing survey telescopes in longitude and latitude as long as there is sufficient sky coverage from a telescope or network of telescopes which may be geographically close. An idealized space-based survey, especially from a satellite orbit much interior to Earth, would offer an advantage over their terrestrial counterparts. We do not consider a cost-benefit analysis for any of the simulations but suspect that a local-area network of telescopes capable of covering much of the sky in a month to V ∼ 21.5 may be administratively, financially, and scientifically the best compromise for reaching 90% completion of NEOs larger than 1 km diameter. 相似文献
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Peter von Ballmoos Jose Alvarez Nicolas Barrière Steve Boggs Andrei Bykov Juan Manuel Del Cura Velayos Filippo Frontera Lorraine Hanlon Margarita Hernanz Emmanuel Hinglais Jordi Isern Pierre Jean Jürgen Kn?dlseder Lucien Kuiper Mark Leising Beno?t Pirard Jean-Pierre Prost Rui M. Curado da Silva Tadayuki Takahashi John Tomsick Roland Walter Andreas Zoglauer 《Experimental Astronomy》2012,34(2):583-622
DUAL will study the origin and evolution of the elements and explores new frontiers of physics: extreme energies that drive powerful stellar explosions and accelerate particles to macroscopic energies; extreme densities that modify the laws of physics around the most compact objects known; and extreme fields that influence matter in a way that is unknown on Earth. The variability of these extreme objects requires continuous all-sky coverage, while detailed study demands an improvement in sensitivity over previous technologies by at least an order of magnitude. The DUAL payload is composed of an All-Sky Compton Imager (ASCI), and two optical modules, the Laue-Lens Optic (LLO) and the Coded-Mask Optic (CMO). The ASCI serves dual roles simultaneously, both as an optimal focal-plane sensor for deep observations with the optical modules and as a sensitive true all-sky telescope in its own right for all-sky surveys and monitoring. While the optical modules are located on the main satellite, the All-Sky Compton Imager is situated on a deployable structure at a distance of 30?m from the satellite. This configuration not only permits to maintain the less massive payload at the focal distance, it also greatly reduces the spacecraft-induced detector background, and, above all it provides ASCI with a continuous all-sky exposure. 相似文献