共查询到20条相似文献，搜索用时 31 毫秒
1.
Peng Qing-yu Mao Wei 《紫金山天文台台刊》1998,(2)
This paper presents a new method to determine precisely the barycentric positions of the outer planets(Saturn - Neptune)by optical observations. It requires the CCD observations from a long focal distance telescope which is used to observe a planet and its satellites and ones from a meridian circle when it works in a CCD drift scanning manner. The key part of the method is tested by the observations with 1 meter telescope of Yunnan Observatory. The result shows that the new method is feasible to carry out. 相似文献
2.
天王星卫星CCD观测的初步分析 总被引：2，自引：1，他引：1
刘建荣 《紫金山天文台台刊》1999,18(4):371-374
１９９５ 年８ 月在上海天文台利用安装在１ ．５６ 米望远镜上的ＣＣＤ 探测器对天王星五颗主要卫星进行了定位试观测。将观测所得的位置资料与其理论值做了比较。结果表明：ＣＣＤ观测的位置精度优于照相观测的结果。这些资料对于卫星轨道的研究是有价值的。 相似文献
3.
暗弱天然卫星与主带小行星相比,具有亮度低、速度变化快的特点.在观测这类天体时,不能简单地延长曝光时间来提高其信噪比.尝试观测多幅短曝光的CCD (chargecoupled device)图像,采用移位堆叠(shift-and-add)方法,希望提高目标成像的信噪比,获得暗弱天然卫星的精确测量结果.使用2018年4月9—12日夜间,中国科学院云南天文台1 m望远镜(1 m望远镜)拍摄的木星5颗暗卫星的229幅CCD图像,实施了移位堆叠试验.为了验证结果的正确性,与相近日期中国科学院云南天文台2.4 m望远镜(2.4 m望远镜)观测的相同木卫图像的测量结果进行了比较和分析.位置归算采用了JPL (Jet Propulsion Laboratory)历表.结果表明,对CCD图像使用移位堆叠方法,通过叠加约10幅曝光时间100 s的图像, 1 m望远镜能观测暗至19等星的不规则天然卫星,而且测量的准确度与2.4 m望远镜的测量结果有良好的一致性. 相似文献
4.
The method of trailed CCD images for observations of asteroid occultations is described. This method was used to observe 9 asteroid occupations at the Lisnyky observational station in 2006 with the telescope AZT-8 (D= 0.7m and F= 2.8m) equipped by the CCD ST-8 XME. In the case of occultation of the star TYC 0587-00209-1U by the asteroid 76 Freia in November 4, 2006, the distance between the asteroid center and the star, as well as the time of asteroid occultation were determined. The size of asteroid 76 Freia is determined assuming that its shape is spherically symmetric. In other cases, the minimal distances between the asteroid center and the star are determined. The method makes it possible to observe asteroid occultations with high time resolution. 相似文献
5.
A review of visual and photographic data on the appearance of Uranus indicates that markings frequently occur on the planet. The featureless images obtained by the Stratoscope II balloon telescope are possibly the result of the broad spectral band that was used. Difference, or ratio, picture techniques which enhance color or polarization contrasts are proposed as the basis for Uranus imagery on the '79 MJU Mission. An attempt is made to predict the aspect of Uranus at high resolution on the basis of what is currently known about the Uranus atmosphere. The planet should have no visible surface, the tops of a thick NH3 cloud layer should exist near the 3–4 bar level and there is a very uncertain possibility of a thin, broken CH4 cloud layer near 300 mbar. It is proposed that if the choice of an MJU imaging system rests on Uranus objectives alone (i.e., excluding the satellites) then the system should emphasize photo-polarimetric observations between 5500 and 10 000 Å. If, however, the total mission objectives are the basis of choice then a high resolution imaging system, based on the Mariner Jupiter-Saturn system, but including a solid state silicon array would be a more suitable choice. The performance of such a system at Uranus is analyzed. 相似文献
6.
L. N. Berdnikov A. Yu. Kniazev R. Sefako V. V. Kravtsov S. V. Zhujko 《Astronomy Letters》2014,40(2-3):125-135
In 2008–2013, we obtained 11333 CCD BVI c frames for 57 Cepheids from the General Catalogue of Variable Stars. We performed our observations with the 76-cm telescope of the South African Astronomical Observatory (SAAO, South Africa) and the 40-cm telescope of the Cerro Armazones Astronomical Observatory of the Universidad Católica del Norte (OCA, Chile) using the SBIG ST-10XME CCD camera. The tables of observations, the plots of light curves, and the current light elements are presented. Comparison of our light curves with those constructed from photoelectric observations shows that the differences between their mean magnitudes exceed 0?05 in 20% of the cases. This suggests the necessity of performing CCD observations for all Cepheids. 相似文献
7.
8.
四颗射电源在依巴谷和PPM星表中的光学定位 总被引：1，自引：0，他引：1
利用北京天文台施密特望远镜的CCD巡天资料（BATC）中的20次观测,用IRAF软件处理得到星象中心位置,以依巴谷星表和PPM星表作为参考星表,用底片常数法进行处理,得到4颗河外射电源0851 202,1228 126,1442 101,1749 701的光学位置。文中还对所得到的位置与射电位置作了比较。 相似文献
9.
《Icarus》1987,69(2):230-238
Radiometric measurement of Uranus and Neptune near 21 and 32 μm have been made with filters with widths of 8 and 5 μm, respectively. The observations at 21 μm, made on 1985 June 19 at the NASA Infrared telescope facility at Mauna Kea, Hawaii, were calibrated against α Boo and corresponded to brightness temperatures of 54.1 ± 0.3 K for Uranus and 58.1 ± 0.3 K for Neptune. The observations at 32 μm were made on three nights: 1983 May 1 and 1984 May 30 and 31, also at the NASA IRTF. Calibrated against the Jovian satellites Callisto (J4) and Ganymede (J3), these measurements corresponded to brightness temperatures of 51.8 ± 1.5 K for Uranus and 55.6 ± 1.2 K for Neptune. The observations are consistent with higher-resolution studies and confirm the general decrease of brightness temperatures going from about 20 to 30 μm. 相似文献
10.
王海民 《中国天文和天体物理学报》1994,(3)
１９９１年７月１１日日食期间，在大熊湖天文台进行了白光观测．图象是用６５ｃｍ反射系统和ＯＳＬ的ＣＣＤ获得的．月亮边缘始终包含在视场之中，从模糊的月亮边缘轮廓推得了一维的视宁度点扩散函数（ＰＳＦ），其中包含了望远镜引起的畸变。当天的ＰＳＦ的宽度介于０．８到１．３弧秒之间。假设存在圆柱对称性，则可得到二维的ＰＳＦ。然后，运用视宁度函数，对所观测的白光像消卷积。复原方法将观测到的ｒｍｓ反衬值由５％增强到１８％；亮桥可能亮于正常的光球强度；暗的半影纤维可能暗到正常光球的５０％；而亮纤维可能达到正常光球值。 相似文献
11.
After a CCD image of the four Galilean satellites of Jupiter is obtained by a long focal length telescope, we can compare the theoretical positions of these satellites with their pixel positions so as to obtain the calibration parameters of the CCD field of view. In theory, when two of the four satellites have small enough separation, their relative positional measurement will have a good accuracy since the error existing in the solved calibration parameters has a direct proportional effect on the separation of the two satellites. The 347 CCD images taken by 1-m long focal length telescope at Yunnan Observatory in 2002-2005 are used to perform the experimental test. After we improve the centroid algorithm for the satellites and our former halo-removal technique, the results show that the positional measurement of two small-separation satellites has an external precision as good as 0.01-0.03 arcsec. This precision has comparability as that from rarely occurring mutual events of the Galilean satellites. This experiment confirms the finding of the “precision premium” firstly presented by Pascu [1994. An appraisal of the USNO program of photographic astrometry of bright planetary satellites. In: Morrison, L.V., Gilmore, G.F., (Eds.), Galatic and Solar System Optical Astrometry, pp. 304-311] using photographic observations. We believe that this type of observations, besides mutual event observations, might also be used to improve our knowledge of the orbital motions of the Galilean satellites because of its much more opportunities. 相似文献
12.
CCD images of comet P/Swift-Tuttle, obtained in April 1994 with the 2.2m telescope at ESO La Silla/Chile, showed a comaless stellar nucleus. From absolute photometry we estimated the equivalent radius of the cometary nucleus to be about 11 km (assuming an albedo of 0.04 as for P/Halley) for two rotation phase angles which differ by about 75 deg. From that we conclude that the nucleus is either of rather spherical shape or that the viewing geometry was almost pole-on during our observations.An analysis of the plasma tail and inner coma of the comet by means of photographic plates and CCD images through IHW and BVR filters, obtained with the 80cm Schmidt camera and the 1.2m telescope at Calar Alto/Spain in November 1992, revealed several tail rays, head streamers and substructures in brightness excess areas in the coma. While some of the tail rays extended to several million km nuclear distance, most of them can be traced to starting points which lie in a region just 20000–35000 km projected distance tailward from the nucleus. 相似文献
13.
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
14.
T. P. Kiseleva S. M. Chanturiya T. A. Vasil’eva O. A. Kalinichenko 《Solar System Research》2012,46(6):436-441
We present and discuss the results of the astrometry project during which we observed the satellites of Mars, Jupiter, Saturn, Uranus, and Neptune at the Abastumani Astrophysical Observatory (Georgia) between 1983 and 1994. Observations at the Abastumani Observatory were performed with the double Zeiss astrograph (DZA: D/F = 400/3024 mm) and AZT-11 telescope (F = 16 m). We processed a large array of observations and determined exact coordinates of the planets and their satellites in a system of reference stars of modern catalogues as well as relative coordinates of the satellites. The results were compared with modern ephemerides using the MULTI-SAT software. The comparison enabled us to estimate the accuracy of observations (their random and systematic uncertainties) and the accuracy of modern theories of the motion of planets and their satellites. Random uncertainties of observations are estimated to be 0.10??C0.40?? for various objects and observational conditions. Observational results obtained for Uranus, Neptune and the satellites Titania and Oberon were shown to deviate appreciably and systematically from theories of their motion. The results of observations are presented in the Pulkovo database for Solar System bodies that is available at the website http://www.puldb.ru. 相似文献
15.
天然卫星的位置测量在天体测量和天体力学中都有重要意义。国外有人对天王星卫星位置测量应用新的图象处理方法得到了高精度的卫星观测资料。利用云南天文台１米望远镜上获得的两颗卫星的ＳＲＴ的ＣＣＤ观测资料进行了新老图象处理方法的比较研究。当用两颗卫星直接作定标测量ＣＣＤ的比例尺和指向时表明：主星晕的处理对卫星位置的测量非常重要。去晕处理后,测得的比例尺和指向的弥散将大为减少。 相似文献
16.
As the 7 December 2007 equinox of Uranus approached, collaboration between ring and atmosphere observers in the summer and fall of 2007 produced a substantial collection of ground-based observations using the 10-m Keck telescope with adaptive optics and space-based observations with the Hubble Space Telescope. Both near-infrared and visible-wavelength imaging and spatially resolved near-infrared spectroscopic observations were obtained. We used observations spanning the period from 7 June 2007 through 9 September 2007 to identify and track cloud features, determine atmospheric motions, characterize cloud morphology and dynamics, and define changes in atmospheric band structure. Atmospheric motions were obtained over a wider range of latitudes than previously was possible, extending to 73°N, and for 28 cloud features we obtained extremely high wind-speed accuracy through extended tracking times. We confirmed the existence of the suspected northern hemisphere prograde jet, locating its peak near 58°N. The new results confirm a small N-S asymmetry in the zonal wind profile, and the lack of any change in the southern hemisphere between 1986 (near solstice) and 2007 (near equinox) suggests that the asymmetry may be permanent rather than seasonally reversing. In the 2007 images, we found two prominent groups of discrete cloud features with very long lifetimes. The one near 30°S has departed from its previous oscillatory motion and started a significant northward drift, accompanied by substantial morphological changes. The complex of features near 30°N remained at a nearly fixed latitude, while exhibiting some characteristics of a dark spot accompanied by bright companion features. Smaller and less stable features were used to track cloud motions at other latitudes, some of which lasted over many planet rotations, though many could not be tracked beyond a single transit. A bright band has developed near 45°N, while the bright band near 45°S has begun to decline, both events in agreement with the idea that the asymmetric band structure of Uranus is a delayed response to solar forcing, but with a surprisingly short delay of only a few years. 相似文献
17.
A tip-tilt wavefront (image displacement) corrector has been designed and fabricated to increase the efficiency of direct imaging with large-sized CCD cameras. A plane-parallel glass plate tilting in two mutually perpendicular directions at an angle large enough to compensate for an image displacement of±16″ on a telescope with F ≈ 20 m forms the basis of the device. The device allows up to ≈20 corrections per second to be made when a ～14m reference star is used. We investigate the effects of aberrations introduced by the plate on the image quality. We present the results of test observations with the corrector performed on the 1.25-m ZTE telescope at the Crimean Station of the Sternberg Astronomical Institute and the 1.5-m AZT-22 telescope at the Maidanak Observatory, where test images with 1-h exposures that completely realized atmospheric seeing were obtained. 相似文献
18.
A. A. Dement’eva 《Solar System Research》2014,48(3):194-201
The positions of Uranus were observed astrometrically with a CCD detector attached to the Pulkovo Normal astrograph (D/F = 0.33 m/3.5 m, S2C CCD, FOV 18′ × 16′). We provide the positions in the time interval from 2006 to 2011. Reduction of the CCD images was made with reference to the UCAC3 catalogue. The (O-C) values were calculated using the “Natural Satellites Service”. The results were compared with two contemporary theories of Uranus’s motion: INPOP10 and DE414/LE414. The obtained equatorial coordinates correspond well to both theories. On average, (O-C) over both coordinates relative to both theories are 0.1″. 相似文献
19.
M. Assafin R.P. Campos D.N. da Silva Neto A.H. Andrei 《Planetary and Space Science》2008,56(14):1882-1887
Ground-based observations of faint satellites nearby their planets with 1-2 m class telescopes usually do not allow for high quality astrometry and photometry, due to saturation by the primary or to poor S/N ratio on the satellite images, generally embedded on the scattered light of the planet. Earth-based observations of the Uranus satellites’ upcoming mutual events in 2007-2008 are no exception. In most cases, the event will take place at 4 arcs or less from the planet, with “planet minus satellite” brightness differences of 10 magnitudes. So as to make feasible the observations of these important phenomena, we have developed a prototype of a coronagraph of simple design making use of good quality commercial optical systems. Pilot tests made with this coronagraph with a telescope of show that it is possible to obtain S/N ratios of 50 or higher for 10 s exposures, for satellites as close as 2 Uranus radii from the planet center. We have also developed numerical algorithms which perform digital coronagraphy in the images, with the elimination of the influence of the planets’ scattered light. This procedure considerably improves the S/N ratio of the satellite images (with or without a coronagraph instrument) and shall be applied in the reduction of the observations of the Uranus events so as to achieve the highest possible photometric and astrometric quality. 相似文献
20.
Regular positional observations of minor planets in Nikolaev Astronomical Observatory have been begun with installation of photographic Zone Astrograph in 1961. The observations of 19 selected minor planets up to 12 magnitude were obtained for 36 years. Accuracy of the photographic positions of minor planets is rather high, 0.15′′-0.19′′. These positions were used for improvement of the system of fundamental catalogue and determination of its orientation to the dynamical reference frame. CCD observations of asteroids have been begun at the Zone Astrograph in 2000. There was obtained about the same accuracy, as in photographic observations. During 2004-2006 NAO participated in international collaboration with TUBITAK National Observatory (Turkey) and Kazan State University (Russia) in positional and photometric observations of small Solar system bodies. About four thousands of CCD images for 58 asteroids of 11-18 mag were obtained with internal and external errors of 30-80 mas of a single determination. Some of these observations, as well as the observations of the Minor Planet Center, are being used for the current asteroid mass determinations in Nikolaev observatory. Available results allow us to consider the Russian-Turkish telescope RTT150 as a good candidate for ground-based astrometry support of the future space mission GAIA, moreover in the period before GAIA. 相似文献