共查询到19条相似文献，搜索用时 140 毫秒
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传统的大气湍流理论始于大约３０年前。湍流理论的发展使得天文学家对大气湍流对天文观测的影响有了很好的认识，尤其是它为天文台选址和天文高分辨率技术提供了基础。近年来新的天文观测对已传统的大气湍流理论提出了挑战，并可能给地面天文观测带来一场革命。在回顾了大气湍流理论的发展历史后对传统大气湍流理论的基本特性及其应用作了系统的综述，并介绍了新的天文观测事实以及为此而提出的新的大气湍流理论模型。 相似文献
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综述了大气光学湍流探测技术的最新进展,对近年来光学湍流探测设备进行简要总结。通过对光学湍流特征参数的介绍,分析了大气光学湍流探测在天文观测中日趋重要的作用。重点介绍了微温脉动仪、DIMM、MASS、SCIDAR等技术的原理与观测。总结国内大气光学湍流探测技术的现状,展望其在天文领域应用的未来发展趋势。 相似文献
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大气湍流极大限制了地基大口径望远镜观测天文目标图像的空间分辨率.根据最大似然估计原理,提出了用实际光学带宽约束的可有效减小天文观测图像中大气湍流影响的盲反卷积方法,通过共轭梯度优化算法使卷积误差函数趋向最小.建立了望远镜光学系统参数和图像频域带宽的关系,采用变量正性约束、点扩散函数带宽有限约束,提高算法的收敛性.为避免图像处理中有效傅立叶变换频率超出截止频率,要求采集望远镜焦面图像时单个成像单元(如CCD像素单元)应小于四分之一衍射斑直径.算法中未用目标支持域约束,所提出的方法适用于全视场天文图像恢复.用计算机模拟和对实际天文目标双鱼座图像数据的恢复结果验证了所提出方法的有效性. 相似文献
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微温传感器测量近地面大气湍流分布的建议 总被引：1，自引：0，他引：1
根据大气湍流温度结构函数的基本定律，推导了用于测量近地面大气湍流强度分布以及对天文视宁度贡献的关系式；提出了进行该项测量的具体方案以及数据处理过程。 相似文献
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建立在子午—卯酉交替观测原理基础上的低纬子午环（ＬｏｗＬａｔｉ－ｔｕｄｅＭｅｒｉｄｉａｎＣｉｒｃｌｅ）即将出厂投入调试及试运行阶段，进一步研究天文蒙气差修正将是低纬子午环进行高精度观测的重要保证之一。作为对天文蒙气差修正的初步研究，本文首先分析了影响天文蒙气差的主要气象因素，对蒙气差随各种条件的变化情况进行了讨论；在此基础上，推算了大气平面平行层模型以及同心球层模型下的蒙气差值，论述了蒙气差表的编制方法，进而对各种蒙气差理论公式计算所得的修正值进行了分析比较；针对理论计算蒙气差值精度的不足，本文着重阐述了利用低纬子午环（ＬＬＭＣ）进行大气蒙气差实测的方法、原理，较为详尽的说明传统的方法不能满足实测大气折射的要求，而低纬子午环由于自身一些新的特点，能够满足Ｔｅｌｅｋｉ所提出的四个要求；在此基础上推导了相应的计算公式并进一步探讨了实测大气等密度倾斜的方法，最后给出了相应的精度估计，就如何建立一个适合于观测点的实用的实测大气模型进行了探讨 相似文献
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侯金良 《中国科学院上海天文台年刊》1989,(10):66-76
本以大气湍流理论为基础，对上海天台佘山站大气相干长度进行了实测，结果约为6厘米。同时利用两年的高空气气象资料分析了上海地区大气湍流特性，计算了水汽含量，对该地区光学和红外天了初步的定量研究，认为该地区可见光观测的最佳时机是夏秋季节，近红外波段的天观测变是可行的。 相似文献
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基于相位差方法的天文目标高分辨率成像,是利用在焦面和离焦位置上同时采集的一对或者多对短曝光图像,对目标和大气湍流引入的波前相位分布进行估计．在计算机模拟望远镜成像系统和相位差方法图像采集过程的基础上,利用信号估计和最优化理论,确定了高斯噪声模型下的目标函数,采用适合于大规模无约束优化的有限内存拟牛顿法对图像恢复问题进行了数值求解．恢复结果表明,基于相位差方法的高分辨成像技术,可以有效地克服大气湍流的影响,解决天文扩展目标的图像恢复问题． 相似文献
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大气折射是天体测量最基本的问题之一，它影响着天体位置测定的精度。气象资料自动采集系统是自动计算大气折射必不可少的仪器，为观测结果和气象的相关分析提供了可能．本文介绍的气象资料自动采集系统，可实时采集并可用于其它天文观测仪器． 相似文献
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B. E. Burke J. A. Gregory R.W. Mountain B. B. Kosicki E. D. Savoye P. J. Daniels V. S. Dolat T. L. Lind A. H. Loomis D. J. Young G. A. Luppino J. L. Tonry 《Experimental Astronomy》1998,8(1):31-40
We describe recent work in the area of large, back-illuminated CCD imagers at M.I.T. Lincoln Laboratory as well as new technology applicable to astronomy. We completed in 1995 the development of a 2560 x 1960-pixel frame-transfer imager that filled a 100-mm wafer and several back-illuminated versions of this device were completed. More recently we have begun the development, in collaboration with the U. of Hawaii, of a three-side abuttable 2k x 4k CCD for a multi-chip focal plane. In the unused chord area of the wafer layout, we added test imagers as development vehicles for blooming control and for the demonstration of a CCD that is capable of charge transfer in all four directions. We expect the latter to find application as an electronic means of performing tip-tilt correction to compensate for atmospheric turbulence. 相似文献
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回顾了作为实用天文学和大地测量学中基本研究课题之一的大气折射函数研究的最新进展;介绍了近几年发展的大气折射母函数方法。对如今广泛地应用在空间测量技术中的几种映射函数,如ＣｆＡ２．２、ＭＴＴ等模型作出评述;特别分析了ＮＭＦ模型的优点和不足之处。还介绍了由大气折射母函数方法引出的大气延迟新连分式映射函数和天文大气折射的映射函数方法,利用ＶＬＢＩ实验中高度截止角与基线长变化的关系和探空气球（ｒａｄｉｏｓ 相似文献
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M.S. Dimitrijevi&#x; 《Astronomische Nachrichten》2002,323(6):570-573
The contribution to European astronomy of Milutin Milanković is analyzed. A crater on the far side of the Moon, a crater on Mars, and asteroid 1605 are named after this most distinguished Serbian astronomer. He explained the phenomenon of the ice ages by an astronomical theory. Milanković elucidated also the history of the Earth's climate as well as that of planet Mars, and in addition he was the author of the mathematical theory of climate and of the Earth's polar motion. He did important contributions to celestial mechanics and the history of astronomy, and was a great popularizator of science. At the orthodox church council in 1923 in Istanbul, he submitted a proposal concerning the reform of the calendar, elaborated by him and by Maksim Trpković, providing for a more exact calendar than the Gregorian one. The calendar of Milanković is now used by some orthodox churches, such as the Greek and Romanian ones. 相似文献
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Atmospheric optics is the study of optical effects induced by the atmosphere on light propagating from distant sources. Of particular concern to astronomers is atmospheric turbulence, which limits the performance of ground-based telescopes. The past two decades have seen remarkable growth in the capabilities and performance of adaptive optics (AO) systems. These opto-mechanical systems actively compensate for the blurring effect of the Earth’s turbulent atmosphere. By sensing, and correcting, wavefront distortion introduced by atmospheric index-of-refraction variations, AO systems can produce images with resolution approaching the diffraction limit of the telescope at near-infrared wavelengths. This review highlights the physical processes and fundamental relations of atmospheric optics that are most relevant to astronomy, and discusses the techniques used to characterize atmospheric turbulence. The fundamentals of AO are then introduced and the many types of advanced AO systems that have been developed are described. The principles of each are outlined, and the performance and limitations are examined. Aspects of photometric and astrometric measurements of AO-corrected images are considered. The paper concludes with a discussion of some of the challenges related to current and future AO systems, particularly those that will equip the next generation of large, ground-based optical and infrared telescopes. 相似文献
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With its unprecedented light-collecting area for night-sky observations, the Cherenkov Telescope Array (CTA) holds great potential for also optical stellar astronomy, in particular as a multi-element intensity interferometer for realizing imaging with sub-milliarcsecond angular resolution. Such an order-of-magnitude increase of the spatial resolution achieved in optical astronomy will reveal the surfaces of rotationally flattened stars with structures in their circumstellar disks and winds, or the gas flows between close binaries. Image reconstruction is feasible from the second-order coherence of light, measured as the temporal correlations of arrival times between photons recorded in different telescopes. This technique (once pioneered by Hanbury Brown and Twiss) connects telescopes only with electronic signals and is practically insensitive to atmospheric turbulence and to imperfections in telescope optics. Detector and telescope requirements are very similar to those for imaging air Cherenkov observatories, the main difference being the signal processing (calculating cross correlations between single camera pixels in pairs of telescopes). Observations of brighter stars are not limited by sky brightness, permitting efficient CTA use during also bright-Moon periods. While other concepts have been proposed to realize kilometer-scale optical interferometers of conventional amplitude (phase-) type, both in space and on the ground, their complexity places them much further into the future than CTA, which thus could become the first kilometer-scale optical imager in astronomy. 相似文献
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月球激光测距是国内外所瞩目的宏伟目标 ,代表着单光子探测技术的高峰。本论文的目的是探索提高激光测月回波光子数的新方法 ,进而增加激光测月成功的几率。其思路是源于一个新的想法 :在激光测月过程中引入大气波前倾斜量实时补偿的技术。首先介绍激光测月的现状和其难度所在 :回波光子数太少 ,基本上属于亚光子探测范畴。在现有技术条件下 ,本文对影响激光测月回波光子数的因素逐一进行分析讨论 ,提出应该把激光束截面能量分布和大气湍流效应包括进去。为此分析讨论了大气湍流和大气中光场的基本统计性质、激光束在大气中传输时所受大气湍流的影响以及大气湍流对激光测距的影响 ,得出大气湍流特别对激光测月有着明显影响的结论。在此基础上对传统的激光测距方程进行了修正 ,使其应用到激光测月时更符合真实的情况 ,从而指导补偿的进行。涉及到在激光测月中对受大气湍流而畸变的激光束进行补偿 ,本文抓住重点 ,通过分析看出对大气倾斜量的实时补偿是提高激光测月回波光子数的重要因素。结合激光测月以及云南天文台现有测距系统的实际情况 ,本文独创性地提出利用激光测月目标近旁一定大小区域的扩展面源探测与计算大气倾斜量 ,然后对激光测月中的激光束进行大气倾斜量实时补偿的新技术方法。在分析比较 相似文献
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