共查询到20条相似文献,搜索用时 109 毫秒
1.
O. V. Bolotina A. N. Samoilenko S. L. Bolotin V. L. Kozel 《Kinematics and Physics of Celestial Bodies》2008,24(6):300-308
We analyze the local geodetic ties between the VLBI, LLR, and GPS reference points of the Simeiz-Katziveli collocation station. The conclusion about the instability of this geodynamic test area is confirmed. We conclude that regular, with a period of 1–2.5 years, redeterminations of the local geodetic ties at this collocation station are necessary. A linear model of the time variation in the estimates of the local geodetic ties is constructed for this test area. The estimates of the local geodetic ties are compared with the differences between the corresponding coordinates of the reference points specified in ITRF2000. We conclude that there are systematic errors in ITRF2000 related to an incorrect determination of the velocities for the reference points of the collocation station with identical DOMES numbers. We suggest assigning different DOMES numbers to the reference points of unstable geodynamic test areas. The estimates of the local geodetic ties are compared with the differences between the corresponding coordinates of the reference points obtained from individual VLBI, LLR, and GPS solutions. These were found to be in disagreement. 相似文献
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A. N. Samoilenko A. V. Adamenko O. V. Bolotina V. V. Zayets O. A. Khoda 《Kinematics and Physics of Celestial Bodies》2008,24(6):309-316
The high-precision coordinates of reference (reduction) points of stations located in the geodynamic area of the MAO NAS of Ukraine were determined in the local topocentric coordinate system. The local geodetic ties (eccentricities) between the reference points of the GPS station “Kiev/Goloseev” and satellite laser location station “Goloseev-Kiev” that are equal to 100.2358 m, ?11.0398 m, ?85.8256 m on the X, Y, Z axes, respectively, were obtained in the ITRF97 system as of the epoch 1997.0. The coordinates of the reference point of the station “Goloseev-Kiev” were determined in the ITRF97 system as of the epoch 1997.0 by adding local geodetic ties to the coordinates of the reference point of the GPS station “Kiev/Goloseev.” They were compared with the estimates of the coordinates of these stations obtained by the methods of cosmic geodesy and geodynamics. The local deformations of the geodynamic area that took place in the 1997–2006 period were estimated and the conclusion was made about the existence of certain trends with respect to the local displacements of the points of the geodynamic area of the MAO NAS of Ukraine. 相似文献
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Heinrich Eichhorn 《Celestial Mechanics and Dynamical Astronomy》1984,34(1-4):11-18
A frame of reference is defined asinertial if the coordinates of bodies, predicted with respect to it on the basis of some mechanical principles, agree with those actually observed. It is pointed out that within the framework of Newtonian mechanics the concept of an inertial frame of reference is global, but within the framework of general relativity only local. The relativistic local inertial frame of the Solar System moves with respect to the Newtonian global frame by the amount of geodetic precession. In all rigor, the concept of a globally privileged inertial system has been rendered meaningless by general relativity, even though the concept of an inertial reference frame remains useful in contemporary celestial mechanics. It is further pointed out that none of the practically determined approximations to an inertial frame of reference (e.g., the dynamical reference frame of celestial mechanics, the FK5) must be regarded as adefinition of an inertial system itself. 相似文献
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The European VLBI Network has been performing a regular series of geodetic observations (EUROPE) whose main aim is to detect and monitor deformations in the European part of the Eurasian plate with high accuracy. The interaction between the African and Eurasian plates drives the tectonic motions detected in the Southern part of Europe that, with the spreading of the Middle Atlantic ridge and other local geophysical (e.g., post-glacial rebound) and geological phenomena, determine the overall crustal deformation of the region. We present the latest results obtained from the analysis of the EUROPE campaigns of observations; for certain stations, we have integrated other data acquired during different campaigns that involved at least three antennae of the network. In particular, for Ny Aalesund, we had to increase further the amount of data by using 144 experiments providing a more continuous and redundant data span to ensure a stronger statistical solution and a network with better spatial distribution. We present the velocities estimated for the antennas in the European geodetic network, along with an interpretation within their local geophysical frame. 相似文献
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区域GPS网实时计算可降水量的若干问题 总被引:1,自引:0,他引:1
SONG Shuli ZHU Wenyao 《中国科学院上海天文台年刊》2003,(1)
目前地基GPS气象学测得的可降水量 (PWV )精度好于 2mm ,但在利用区域GPS网实时计算每个测站上空的PWV时 ,要涉及到很多常规GPS资料处理时所忽略的问题 ,如需考虑数据处理软件和计算方式的选择、站坐标的确定和约束、轨道的使用方法、网外辅助站最佳数量的确定、海潮对实时计算PWV的影响以及实时应用于气象服务时的端部效应等问题。利用上海GPS综合应用网获取的 2 0 0 2年 6、7月份长江三角洲地区入梅前后的数据 ,分析了利用区域性的GPS网实时计算高精度的PWV时要解决的各种问题 ,探讨了其数据处理方案 相似文献
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N. I. Kobanov 《Experimental Astronomy》1994,5(3-4):301-313
A variant to implement a spacecraft (SC) spatial attitude system with respect to the Sun is discussed. The sunward direction and the solar rotation axis are used as reference points. The system is based on measuring spectral line Doppler shift by scanning the solar image along the limb and is self-adjusting for relative spectral line shifts and instrument band shifts. The first harmonic of the signal serves as a basis for accurate adjustment of filter band. The second harmonic phase is used to measure the spacecraft attitude. The application of this method holds the greatest promise when the SO is stabilized by the sunward spinning because this ensures continuous monitoring of the spacecraft attitude.In addition, the method provides information on the precise coordinates of solar surface details during space-borne observations. 相似文献
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Yu. I. Neshpor V. S. Eliseev N. A. Jogolev E. M. Nehay Z. N. Skiruta V. V. Fidelis V. P. Fomin 《Bulletin of the Crimean Astrophysical Observatory》2007,103(1):16-20
Observations of several active galactic nuclei were performed with the GT-48 gamma-ray telescope at CrAO in 2004: 3C 66A, Mk 421, Mk 501, 1H 1426, 1ES 1959, and BL Lac. Very-high-energy (E ≥ 1012 eV) gamma-ray fluxes were recorded from 3C 66A, Mk 421, Mk 501, and 1H 1426 at a confidence level of more than 4σ. Upper limits for the flux of very-high-energy gamma rays are presented for 1ES 1959 and BL Lac. The 2004 observational data for 3C 66A (z = 0.44) confirm the results obtained previously at CrAO. 相似文献
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According to the requirement of high-precision satellite navigation, we have introduced the method for the quasi-realtime monitoring of variations of the regional ionospheric total electron content (TEC) and GPS satellite differential code bias (DCB), based on the dual-frequency carrier-phase smoothed pseudorange data obtained from a regional GPS network in China. Especially, we have studied the feasibility of retrieving DCB independently from the regional GPS networks with different sizes. For this purpose, 3 regional networks based on the countrywide GPS stations are investigated. The comparisons of the computed DCB and VTEC(vertical total electron content) with those of CODE(the Center for Orbit Determination in Europe) indicate that in order to realize a reliable quasi-realtime measurement of DCB by a regional network, there is a certain requirement on the size of the regional network, and that the relative accuracies of the quasi-realtime VTEC and DCB measured by using a Chinese GPS regional network can reach 2.0TECu and 0.25 ns, respectively. 相似文献
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The transition from local horizon and terrestrial BIH-systems to celestial reference frames is well known to be affected by various geodetic parameters such as polar motion (xp(t), yp(t)), UT1-TUC (where UT1 is basically dependent on variations in UT0 and t=time), plumb line deflections (, ) of observation stations, global and local tidal deformations etc. Variations of such quantities with (relative) resolution of the order of 0.001 and better, such as VLBI, demand the application of continuous high-precision (world-wide) geodynamic surveys whenever global theories and sufficient models are not available and the introduction of improved local and global models (geophysical and relativistic) is needed in order to match astrometric observations related to different reference frames. Prediction of parameters for immediate transformation from one system of reference into the other is sometimes of interest.The paperreviews recent results of different observations,points out a number of still open and unresolved problems in observations and modeling, anddiscusses related consequences. Conclusions for geodynamics drawn from comparison of observed data with models based on astronomical and geophysical observations give way to new understanding of basic phenomena of relevance for various disciplines. 相似文献
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The activity of the variable star IN Com is considered using the latest multicolor UBVRI photometry and linear polarimetric observations carried out during a decade. The photometric variability of the star is fully described using the zonal spottedness model developed at the Crimean Astrophysical Observatory (CrAO). Spotted regions cover up to 22% of the total stellar surface, with the difference in temperatures between the quiet photosphere and the spot umbra being 600 K. The spots are located at middle and low latitudes (40°–55°). The intrinsic broad-band linear polarization of IN Com and its rotational modulation in the U band due to local magnetic fields at the most spotted (active) stellar longitudes were detected for the first time. 相似文献
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Based on the observations of solar eclipses performed on the RT-22 radio telescope at CrAO in the wavelength range 2.0–3.5
cm, we consider the fine spatial structure of the microwave emission from the quiet Sun. We have established that the positions
of compact radio sources with a typical size of about 7″.0 and coronal bright points coincide. The mean radio flux exceeds
the level of the quiet Sun by 0.28 sfu. The brightness temperatures increase with wavelength and lie within the range 0.3–2.7
MK. Evidence for a nonthermal nature of the emission from compact radio sources has been obtained. 相似文献
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Constructing and maintaining a stable terrestrial reference frame(TRF) is one of the key objectives of fundamental astronomy and geodesy. The datum realization for all the global TRF versions,such as ITRF2014 and its predecessor ITRF2008, assumes linear time evolution for transformation parameters and then imposes some conditions on these Helmert transformation parameters. In this paper,we investigate a new approach, which is based on weekly estimation of station positions and Helmert transformation parameters from a combination of the solutions of four space-geodetic techniques, i.e.,Satellite Laser Ranging(SLR), Very Long Baseline Interferometry(VLBI), Global Positioning System(GPS) and Doppler Orbitography and Radiopositioning Integrated by Satellite(DORIS). For this study,an interval of one week is chosen because the arc length of the SLR solutions is seven days. The major advantage of this weekly estimated reference frame is that both the non-linear station motions and the non-linear origin motion are implicitly taken into account. In order to study the non-linear behavior of station motions and physical parameters, ITRF2008 is used as a reference. As for datum definition of weekly reference frame, on one hand SLR is the unique technique to realize the origin and determine the scale together with VLBI, and on the other hand the orientation is realized via no net rotation with respect to ITRF2005 on a subset of core stations. Given the fact that without enough collocations an inter-technique combined TRF could not exist, the selection and relative weight of local ties surveyed at co-location sites are critical issues. To get stable results, we first assume that, if there were no events such as equipment changes between the measurement epoch of the local tie and that of the spacegeodetic solution, the relative position between the two co-located stations should be invariant and this local tie could be used for computing the inter-technique combined reference frame in those weeks during the stable period of this tie. The resulting time series of both station positions and transformation parameters are studied in detail and are compared with ITRF2008. The residual station positions in the weekly combined reference frame are usually in the range of two millimeters without any periodic characteristic, but the residual station positions, when subtracting the regularized station position in ITRF2008, may reach a magnitude of a few centimeters and seem to have a significant annual signal.The physical parameter series between the weekly reference frame and ITRF2008 also show the obvious existence of an annual signal and reach a magnitude of one centimeter for origin motion and two parts per billion(ppb) for scale. 相似文献
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1979-1999全球天测与测地VLBI观测资料处理结果与讨论 总被引:1,自引:0,他引:1
采用国际地民服务(IERS)1996年规范和上海天文台甚长基线干涉测量(VLBI)资料分析软件,对自1979年8月以来全球约2900次天测与测地VIBL实验进行了综合归算,得到601颗河外射电源在J2000.0的坐标、101台站在J1997.0的坐标和运动速度、以及约20年地地球定向参数序列。与国际相关结果的比较表明,归算结果不存在显著系统差。通过对归算结果的分析,指出目前国际上评估天球参考架局部 相似文献
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A. E. Volvach A. A. Berezhnoi L. N. Volvach I. D. Strepka E. A. Volvach 《Bulletin of the Crimean Astrophysical Observatory》2011,107(1):122-124
Investigations on OH maser lines in comets have been performed with the RT-22 at CrAO. The results of observations of 9P/Temper1
and Lulin C/2007 N3 comets in the OH molecule line at a wavelength of 18 cm are presented. An original technique for observation
data analysis has been developed. The gas production rate of OH molecules in these comets is estimated. 相似文献