共查询到20条相似文献,搜索用时 78 毫秒
1.
2.
3.
4.
5.
1996年9月2日至9月6日云南天文台CCD实验室对北京天文台太阳气球望远镜主探测器DALSACA-D7-1024T CCD相机各种主要参数进行了检测,测试结果令人满意。 相似文献
6.
7.
CCD探测器在地面天体测量中的应用 总被引:2,自引:0,他引:2
CCD技术在天体测量领域的应用已得到很大发展,本文回顾了10年来CCD技术应用于大型望远镜和子千环上的基本情况和所取的成果,分析了这些应用中所存在的三个主要问题,并对这些问题提出了相应的解决途径,这些问题的解决,将能促进地面基本天体测量的精度和效率跨上一个新台阶。 相似文献
8.
理论上硅CCD在0.1nm到1.1μm之间都有响应,但通常此种器件在800nm以后量子效率下降明显,一般会小于50%,其中最主要的原因是近红外光子的吸收深度大于CCD的外延层厚度,使大量光子穿透整个器件。显然增加外延层的厚度是解决这一问题的良好途径,但随着外延层的增加,必须使用高阻抗的材料,否则会明显的减低分辨率,另外增透膜的使用也会使量子效率大幅度提高,而且有效的减弱了干涉条纹的影响,新型P沟道 相似文献
9.
本文作者用北京天文台兴隆站2.16米望远镜及卡焦CCD摄谱仪,观测到一颗红移为1.66的类星体,讨论了该望远镜卡焦摄谱系统的总体光效率。 相似文献
10.
本文首先回顾了目前上CCD控制器的最新进展。介绍了中国的第一套天文用CCD探测器系统:云南天文台#D1CCD系统。 相似文献
11.
目标的完备性搜索是开展近地小行星预警和防御的前提. 为量化评价近地小行星观测效能, 提高监测设备使用效率, 提出一种综合望远镜参数和测站天文条件的观测效能评估方法. 以观测目标信噪比作为检测指标, 设定检测条件形成目标检测方法, 定义评价指标用于评估近地小行星观测效能. 再基于近地小行星轨道数据和尺度分布模型, 建立近地小行星轨道数据模拟样本库. 最后选取中国科学院紫金山天文台盱眙观测站和中国科学院国家天文台冷湖观测台址, 仿真分析近地天体望远镜对直径0.01--30km近地小行星的观测效能, 结果表明: 不考虑两观测站年有效观测时间差异, 近地天体望远镜在冷湖观测全尺寸模拟样本的效能比在盱眙提高了5.21倍, 其中对1km以上直径目标的观测效能相当, 对1km以下直径目标的观测效能差异开始显现, 对0.1km以下直径目标冷湖优势更显著. 相似文献
12.
《Chinese Astronomy and Astrophysics》2007,31(2):109-116
The effect of variation of radiative efficiency on the growth of the black hole mass is discussed. In the process of accretion, the black hole's angular momentum varies, resulting in a variation of the radiative efficiency, and the growth of the black hole mass is thereby affected. For the exponential growth model of back holes and taking into account the effect of a varying radiative efficiency, the equation for the growth of the black hole mass is solved numerically. Compared to the model that assumes a constant radiative efficiency, the result indicates that variation of radiative efficiency has a marked, retarding effect on the growth of the black hole mass. This model can explain quantitatively some recent observational results. 相似文献
13.
14.
We study the dynamic efficiency of conversion of kinetic-to-thermal/magnetic energy of internal shocks in relativistic magnetized outflows. We model internal shocks as being caused by collisions of shells of plasma with the same energy flux and a non-zero relative velocity. The contact surface, where the interaction between the shells takes place, can break up either into two oppositely moving shocks (in the frame where the contact surface is at rest), or into a reverse shock and a forward rarefaction. We find that for moderately magnetized shocks (magnetization σ≃ 0.1 ), the dynamic efficiency in a single two-shell interaction can be as large as 40 per cent. Thus, the dynamic efficiency of moderately magnetized shocks is larger than in the corresponding unmagnetized two-shell interaction. If the slower shell propagates with a sufficiently large velocity, the efficiency is only weakly dependent on its Lorentz factor. Consequently, the dynamic efficiency of shell interactions in the magnetized flow of blazars and gamma-ray bursts is effectively the same. These results are quantitatively rather independent on the equation of state of the plasma. The radiative efficiency of the process is expected to be a fraction f r < 1 of the estimated dynamic one, the exact value of f r depending on the particularities of the emission processes which radiate away the thermal or magnetic energy of the shocked states. 相似文献
15.
Manjiri Bhat Sanjeev Dhurandhar Naresh Dadhich 《Journal of Astrophysics and Astronomy》1985,6(2):85-100
We have studied in detail the energetics of Kerr-Newman black hole by the Penrose process using charged particles. It turns out that the presence of electromagnetic field offers very favourable conditions for energy extraction by allowing for a region with enlarged negative energy states much beyondr = 2M, and higher negative values for energy. However, when uncharged particles are involved, the efficiency of the process (defined as the gain in energy/input energy) gets reduced by the presence of charge on the black hole in comparison with the maximum efficiency limit of 20.7 per cent for the Kerr black hole. This fact is overwhelmingly compensated when charged particles are involved as there exists virtually no upper bound on the efficiency. A specific example of over 100 per cent efficiency is given. 相似文献
16.
A. C. Balachandra Swamy 《Astrophysics and Space Science》1992,196(2):179-190
Photoionization and absorbed energy rates have been computed by making use of the latest available semi-empirical solar XUV fluxes and cross-sections for two rocket flights for electron density measurements on 3 March, 1973 and 7 April, 1972 corresponding to low and medium solar active conditions over Thumba. Various heating and cooling rate profiles have been computed by making use of the latest available information. Various efficiency parameters such as photoelectron heating efficiency, photoionization efficiency, and ultraviolet heating efficiency, that are extremely important in understanding the thermal structure of the ionosphere, are clearly defined and distinguished. 相似文献
17.
We use a new self-consistent model to derive the conversion efficiency from rotation power to γ-ray power for pulsars (εth ). Our result indicates that εth ∝τ6/7 P 2 , where τ and P are the characteristic age and period of the pulsar, which shows that although the efficiency increases with the characteristic age of the pulsar, it also depends on the pulsar period. We test our model results with the survey of high-energy γ-rays from pulsars by EGRET. Our model not only successfully explains the efficiency of the confirmed γ-ray pulsars but also explains why the γ-ray efficiency of millisecond pulsars is so low. 相似文献
18.
Yong Zhao Zhou Fan Juan-Juan Ren Liang Ge Xiao-Ming Zhang Hong-Bin Li Hui-Juan Wang Jian-Feng Wang Peng Qiu Xiao-Jun Jiang 《天文和天体物理学研究(英文版)》2018,(9)
The Beijing Faint Object Spectrograph and Camera(BFOSC) is one of the most important instruments operating in conjunction with the 2.16-m telescope at Xinglong Observatory. Every year there are~20 SCI-papers published based on observational data acquired with this telescope. In this work,we have systemically measured the total efficiency of the BFOSC that operates as part of the 2.16-m reflector, based on observations of two ESO flux standard stars. We have obtained the total efficiencies of the BFOSC instrument of different grisms with various slit widths in almost all ranges, and analyzed factors which effect the efficiency of this telescope and spectrograph. For astronomical observers, the result will be useful for them to select a suitable slit width, depending on their scientific goals and weather conditions during observations. For technicians, the result will help them to systemically identify the real efficiency of the telescope and spectrograph, and to further improve the total efficiency and observing capacity of the telescope technically. 相似文献
19.
P. P. Dunphy E. L. Chupp M. Popecki D. J. Forrest D. Lopiano T. Shima H. Spinka G. Glass G. Burleson M. Beddo 《Experimental Astronomy》1992,2(4):233-258
We report on the response of a prototype detector to medium energy neutrons. The neutrons were produced by n-p scattering of a neutron beam on a hydrogen target. The measurements provide unique data on the efficiency and response of large NaI scintillators to neutrons in the energy range 36–709 MeV. We apply the results to the high-energy mode of the Gamma-Ray Spectrometer (GRS) on the Solar Maximum Mission satellite by estimating its efficiency for neutron detection. This estimate is compared to earlier Monte Carlo calculations of the GRS efficiency. 相似文献
20.
D. O. ReVelle 《Earth, Moon, and Planets》2005,97(1-2):1-35
In this paper, we will review recent research on numerous aspects of bolide entry into a planetary atmosphere, including such
topics as the entry dynamics, energetics, ablation, deceleration, fragmentation, luminosity, mechanical wave generation processes,
a total (panchromatic) power budget including differential and integral efficiencies vs. time, etc. Fragmentation, triggered
by stagnation pressures exceeding the bolide breaking strength, has been included with subsequent wake behavior in either
a collective or non-collective behavior limit. We have also utilized the differential panchromatic luminous efficiency of
ReVelle and Ceplecha (2002c, Proceedings of Asteroids, Comets, Meteors ACM 2002, 29 July–2August, 285–288) to compute bolide luminosity. In addition we also introduce the concept of the differential and
integral acoustic/infrasonic efficiency and generalized it to the case of mechanical wave efficiency including internal atmospheric
gravity waves generated during entry. Unlike the other efficiencies which are assumed to be a constant multiple of the luminous
efficiency, the acoustic efficiency is calculated independently using a 'first principles' approach. All of these topics have
been pursued using either a homogeneous or a porous meteoroid model with great success. As a direct result, porosity seems
to be a rather good possibility for explaining anomalous meteoroid behavior in the atmosphere. 相似文献