共查询到20条相似文献,搜索用时 31 毫秒
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现代日晕光度计(Sky Brightness Monitor,SBM)是一种测定天文址点白昼大气参量的精密仪器,它已成为国际上太阳选址工作的重要设备之一。与国外同类设备不同的是,云南天文台研制的现代日晕光度计上的CCD相机系统可以被简单拆卸并保存,有利于选址踏勘阶段的携带和运输。为获取组装现代日晕光度计设备时可能存在的CCD离焦所导致的测量误差,于2011年6月在新疆奇台县和宁夏石嘴山市利用当地稳定的日照条件做了多次CCD大离焦量快变试验。统计结果表明,现代日晕光度计的CCD显著离焦可造成的相对测量误差约在6%之内。在正常情况下,即观测者基本按照物镜旋筒刻线标志在望远镜上安装CCD设备时,日晕测量的相对误差一般远小于6%。因此认为这种系统误差对优良址点的测量影响基本可以忽略。 相似文献
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分析了低光度天文应用时CCD器件的主要噪声源的噪声特性和三种典型CCD读出信号处理方式的噪声抑制效果;提出了天文CCD读出信号的相关多次采样(CMS)处理新方法,并分析了四次采样抑制CCD读出噪声的实验结果。 相似文献
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V. Ya. Molchanov V. M. Lyuty V. F. Esipov S. P. Anikin O. Yu. Makarov N. P. Solodovnikov 《Astronomy Letters》2002,28(10):713-720
We present the results of our tests of an acousto-optical imaging spectrophotometer with a CCD detector for astronomical observations. The tunable acousto-optical filter, based on a paratellurite single crystal with a 13 Å pass band operates in the wavelength range 6300–11000 Å. We obtained image spectra for the planetary nebula NGC 7027 in the Hα line and for Saturn in the methane absorption band, as well as Hα and continuum images for the nuclear region of the Seyfert galaxy NGC 1068. 相似文献
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J.H. Calderón J.H. Calderón I.H. Bustos Fierro I.H. Bustos Fierro R. Melia C. Willimoës C. Willimoës C. Giuppone C. Giuppone 《Astrophysics and Space Science》2004,290(3-4):345-351
The astronomical events registered in photographic plates are unique. A remarkable interest in using old plates in many areas of the current astronomical research is widely recognized by the IAU. There are almost ten thousand plates in several collections at the Córdoba Observatory and most of them are nearly one century old. This photographic material is difficult to handle in order to get the information stored in it. The goal of this project is to make a digital archive of images of these collections. In this first survey plates are being scanned with a standard commercial transparency scanner. These low spatial resolution, low digital resolution and low signal-to-noise ratio images are intended for facilitating handling and visual inspection. However, one arc-second positions can be obtained. Photometric quality has not been yet determined. Otherwise high quality digital images can be acquired with a microdenstitometer based on a scientific grade CCD whose implementation is at its final stage. The possibility of using a better-performance scanner is being evaluated. It is planned to permit the access to low-resolution images via internet. High-resolution images of selected zones will be available upon request. At this first stage, collections totally digitized at low resolution are:Carte du Ciel and Small Magellanic Cloud Zones. Gaviola's Eta Carinae Spectra and Pulkovo Zones are still in process. 相似文献
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The SBIG Model ST-6 CCD Imaging Camera was tested and found suitable for various kinds of astronomical observations on telescopes with apertures from 6 mm to 0.6 m. We discuss different noise sources, linearity, sensitivity, and other detector characteristics. Limits, which they set to the observations and accuracy of data evaluation process, are also discussed. Detection, accurate astrometry, and VR photometry limiting magnitudes are about 21, 20, and 17.5, respectively, with the 0.6-m telescope and 10-min integration time. Detection of 5th magnitude 1-second optical transients is possible with the 6-mm wide-field lens. 相似文献
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Wei Duan Qian Song Ming-Zhi Wei Zhao-Wang Zhao Wei Wang Yu-Heng Zhang Zhi-Wei Feng 《天文和天体物理学研究(英文版)》2021,(1):127-135
As the areas of CCD detectors and CCD mosaics have become larger and larger,the number of readout channels in astronomical cameras has increased accordingly to keep the image readout time within an acceptable range.For the large area cameras or the mosaic cameras,the analog Correlated Double Sampling(aCDS)circuit used in traditional astronomical cameras for suppressing readout noise is difficult to integrate into the camera controllers within the constraints of the space and energy consumption.Recently,digital CDS(dCDS)technology has been developed to solve this problem,which also offers novel analysis and noise suppression methods.In this study,a mathematical model is presented to conveniently analyze the frequency characteristic of a dCDS circuit,which is then simulated by a numerical method for investigating the noise suppression capability with different sampling weights.Importantly,using this model,the extreme point with lowest readout noise can be predicted for a certain dCDS model;and for a specific CCD readout frequency,readout noise can be suppressed by selecting the proper dCDS model.A testing system is then constructed for validating the efficiency of the proposed method. 相似文献
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John Vallerga Jason McPhate Anton Tremsin Oswald Siegmund 《Astrophysics and Space Science》2009,320(1-3):247-250
At the heart of future space-based astronomical UV instruments will be a sensitive UV detector. Though there has been a death of new UV mission opportunities, detector development has continued. Improvements have been made in spatial resolution, dynamic range, detector size, quantum efficiency and background. At the same time the power and mass required to achieve these goals have decreased. We review the current capabilities of microchannel plate based detectors at Berkeley, both in the laboratory and aboard current on-orbit spacecraft. We also discuss what can be expected from the next generation of UV detectors over the next decade. 相似文献
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A. V. Devyatkin D. L. Gorshanov V. V. Kouprianov I. A. Verestchagina 《Solar System Research》2010,44(1):68-80
We describe in detail the Apex I and Apex II software packages created for astrometric and photometric reductions of astronomical
observations with CCD cameras. The Apex I software package has been created for the semiautomatic reduction of astronomical
observations and has a convenient user interface. The Apex II software package allows for the completely automatic reduction
of astrometric and photometric observations to be performed. 相似文献
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SUN Rong-yu ZHAO Chang-yin PING Yi-ding XIONG Jian-ning ZHANG Chen 《Chinese Astronomy and Astrophysics》2012
In the observation of space objects with a full-frame transfer CCD camera, the camera shutter is often removed, and therefore the smeared images are produced, which affect seriously the object detection and location. Based on the difference of geometrical morphology between star images and smears, a mathematical morphology method is proposed to process the smeared images. By comparing the position accuracies of stars and space objects before and after processing, it is veri?ed that the morphological method can effectively remove the smears from astronomical images, and can signi?cantly improve the detection rates and position accuracies of stars and moving objects. The result indicates that this is an effective method to eliminate the smearing effect. 相似文献
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CCD图像数字定心算法的比较 总被引:13,自引:0,他引:13
从CCD采集的数字图像中提取天体的位置和光度信息对于天文研究具有基础意义.其中,恒星星像中心像素位置的精确测量对于天体测量至关重要.针对国际上常用的三种位置测量算法:修正矩方法、Gauss拟合法和中值法,利用实测的CCD图像进行了试验研究.具体地,采用云南天文台1m望远镜观测的CCD图像同时使用这些算法进行了实际测量,根据每幅图像中测得的像素位置,对这三类定心算法进行了比较和精度分析.可视化方法被用于不同阈值的选取和设定比较.实验数据表明,无阈值的二维Gauss拟合方法是一种精度相对较高的定心算法. 相似文献
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A. El-Bassuny Alawy 《Astrophysics and Space Science》2001,277(3):473-495
A new approach is proposed and developed to handle pre-processed CCD frames in order to identify stellar images and derive
their relevant parameters. The present method relies on: 1) identifying stellar images and assigning approximate positions
of their centres using artificial intelligence techniques, 2) accurate determination of the centre coordinates applying an
elementary statistical concept and 3) estimating the image peak intensity as a stellar magnitude measure employing a simple
numerical analysis approach. The method has been coded for personal computer users. A CCD frame of the star cluster M67 was
adopted as a test case. The results obtained are discussed in comparison with the DAOPHOTII ones and the corresponding published
data. Exact coincidence has been found between both results except very few cases. These exceptions have been discussed in
view of both methods' bases and the cluster plates. It has been realized that the method suggested exhibits very simple, extremely
fast and high precise approach in stellar CCD photometry domain. Moreover, it is more capable for handling blended and distorted
stellar images than the DAOPHOTII. These characteristics show the usefulness of the present method in some astronomical applications
such as auto-focusing and auto-guiding sensing approaches beside the main purpose, viz. stellar photometry.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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L. Győri 《Solar physics》2010,267(2):445-461
Accurate heliographic coordinates of objects on the Sun have to be known in several fields of solar physics. One of the factors
that affect the accuracy of the measurements of the heliographic coordinates is the accuracy of the orientation of a solar
image. In this paper the well-known drift method for determining the orientation of the solar image is applied to data taken
with a solar telescope equipped with a CCD camera. The factors that influence the accuracy of the method are systematically
discussed, and the necessary corrections are determined. These factors are as follows: the trajectory of the center of the
solar disk on the CCD with the telescope drive turned off, the astronomical refraction, the change of the declination of the
Sun, and the optical distortion of the telescope. The method can be used on any solar telescope that is equipped with a CCD
camera and is capable of taking solar full-disk images. As an example to illustrate the method and its application, the orientation
of solar images taken with the Gyula heliograph is determined. As a byproduct, a new method to determine the optical distortion
of a solar telescope is proposed. 相似文献
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R. Poggiani 《Experimental Astronomy》2004,18(1-3):109-132
The domain of high speed optical astrophysics is still quite unexplored. The availability of 10 meter diameter telescopes
offers the unique possibility to investigate variability of faint objects at submillisecond time scales. In this paper I describe
the concepts of a photometer and a spectrometer for high speed astronomical observations. The instruments are based on a photon
counting detector developed for high energy physics, the Visible Light Photon Counter (VLPC). The detector has a quantum efficiency
in the visible as high as 88% and performs photon counting with sub microsecond time resolution. The photometer is built using
VLPC arrays. Adding a grating a VLPC array can be used in a time resolved spectrograph with medium resolution. This paper
develops, starting from experimental data, the concept of the two VLPC based instruments and their application to time resolved
photometry and spectroscopy of compact objects (pulsars, cataclysmic variables, low mass X-ray binary systems etc) and optical
counterparts of Gamma Ray Bursts. The high speed optical observations are the ideal complement to X/γ rays and gravitational
wave studies. The application of the instruments to the optical photometry of pulsars, the spectrophotometry of the prompt
optical flash from Gamma Ray Bursts and the study of binary systems are discussed in detail: in the last two applications
the instruments offer better opportunities than existing instruments. 相似文献
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Martin M. Roth 《New Astronomy Reviews》2006,49(10-12):573
From a historical point of view, it was only through the advent of the CCD as a linear, high dynamic range panoramic detector that it became possible to overcome the source confusion problem for stellar photometry, e.g., in star clusters or nearby galaxies. The ability of accurately sampling the point-spread-function (PSF) in two dimensions and to use it as a template for fitting severely overlapping stellar images is of fundamental importance for crowded-field photometry, and has thus become the foundation for the determination of accurate color-magnitude diagrams of globular clusters and the study of resolved stellar populations in nearby galaxies. Analogous to CCDs, the introduction of integral field spectrographs has opened a new avenue for crowded-field 3D spectroscopy, which benefits in the same way from PSF-fitting techniques as CCD photometry does. This paper presents first experience with sampling the PSF in 3D spectroscopy, reviews the effects of atmospheric refraction, discusses background subtraction problems, and presents several science applications as obtained from observations with the PMAS instrument at Calar Alto Observatory. 相似文献
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CCD是天文望远镜中最常见的观测终端设备,也是望远镜自主控制系统中的重要组成部分。随着天文望远镜自主观测需求的不断出现以及技术的快速发展,开源的RTS2软件系统成为目前该领域研究中受到较多关注的系统之一。但RTS2支持的CCD设备较为有限,同时控制接口约定也相对固定。在针对部分特殊的CCD设备(如LAMOST中采用的32台CCD设备、选址用的部分CCD设备)时,仅实现原有类的方法是不够的。在深入分析RTS2源码的基础上,重点从参数、命令、协议扩展方面研究基于原有的Camera类,通过继承的方法构造新的CCD类型,实现对LAMOST项目的 CCD控制,取得了较好的效果,对在RTS2中集成望远镜系统其他类型设备也有较好的参考价值。 相似文献