共查询到20条相似文献，搜索用时 15 毫秒
1.
G. A. Kosmodamianskiy 《Astronomy Letters》2019,45(11):770-777
New versions of the ephemerides for the Galilean satellites of Jupiter (Io, Europa, Ganymede, and Callisto) constructed by numerically integrating the equations of motion of the satellites are presented. The satellite motionmodel takes into account the non-sphericity of Jupiter, the mutual perturbations of the satellites, and the perturbations from the Sun and major planets. The initial satellite motion parameters have been improved based on all the available series of ground-based optical observations spanning the interval 1891-2017, spacecraft observations, and radar observations. As a result, the coefficients of the expansion of the satellite coordinates and velocities in terms of Chebyshev polynomials in the interval 1891- 2025 have been obtained. The root-mean-square errors of the observations and the graphs of comparison of the constructed ephemerides both with the observations and with Lainey's numerical ephemerides are presented. The constructed ephemerides are publicly accessible. 相似文献
2.
Nikolay Emelyanov 《Planetary and Space Science》2010,58(3):411-420
Ephemerides of planetary satellites are needed to address many problems. These ephemerides are used for subsequent observations. A comparison of the available ephemerides with new observations allows the accuracy of the former to be assessed. However, the precision of the ephemerides must be known a priori when solving the tasks. In this paper we formulate and solve the problem of estimating the precision of the ephemerides of outer planetary satellites derived from observations when applied up to the future moments.The methods of assessing the precision of ephemerides involve producing a set of samples of the same ephemeris inferred from observations with different samples of Monte Carlo generated random errors (RO) superimposed onto it. The statistical parameters of simulated observational errors are based on the results of the reduction of real satellite observations. We compute the deviations of the samples of the ephemeris from the standard ephemeris inferred from real observations and adopt the root-mean-square deviation of the apparent coordinates as the precision of the ephemeris. We also use alternative methods: one based on the matrix of covariances of parameter errors (RP), and another one based on bootstrap samples of observations (BS).We use three methods (RO, RP, and BS) to estimate the precision of the ephemerides of all the 107 outer planetary satellites over the 2010-2020 time interval. The precision of the ephemerides of different satellites varies from 0.05 to 4.0 arcsec. For a number of satellites new observations are of vital importance for maintaining the precision of the ephemerides at a level that would allow identification of satellites during the reduction of observations. For some satellites the precision of their ephemerides is of the order of the sizes of their orbits and such satellites can be considered to have been lost. We show that the method of bootstrap samples (BS) can give doubtful results in the cases where there are few observations, which covered a time interval that is shorter than the orbital period of the satellite.Our results suggest obtaining more precise ephemeris making new observations at the times of maximum estimated errors of the ephemeris.All the inferred estimates of the precision of ephemerides are available from the MULTI-SAT ephemeris server: www.imcce.fr/sat (IMCCE), www.sai.msu.ru/neb/nss/index.htm (SAI). 相似文献
3.
E. V. Pitjeva 《Solar System Research》2013,47(5):386-402
The EPM (Ephemerides of Planets and the Moon) numerical ephemerides were first created in the 1970s in support of Russian space flight missions and since then have been constantly improved at IAA RAS. In the following work, the latest version of the planetary part of the EPM2011 numerical ephemerides is presented. The EPM2011 ephemerides are computed using an updated dynamical model, new values of the parameters, and an extended observation database that contains about 680000 positional measurements of various types obtained from 1913 to 2011. The dynamical model takes into account mutual perturbations of the major planets, the Sun, the Moon, 301 massive asteroids, and 21 of the largest trans-Neptunian objects (TNOs), as well as perturbations from the other main-belt asteroids and other TNOs. The EPM ephemerides are computed by numerical integration of the equations of motion of celestial bodies in the parameterized post-Newtonian n-body metric in the BCRS coordinate system for the TDB time scale over a 400-year interval. The ephemerides were oriented to the ICRF system using 213 VLBI observations (taken from 1989 to 2010) of spacecraft near planets with background quasars, the coordinates of which are given in the ICRF system. The accuracy of the constructed ephemerides was verified by comparison with observations and the JPL independent ephemerides DE424. The EPM ephemerides are used in astronavigation (they form the basis of the Astronomical Yearbook and are planned to be utilized in GLONASS and LUNA-RESURS programs) and various research, including the estimation of the solar oblateness, the parameters of the rotation of Mars, and the total mass of the asteroid main belt and TNOs, as well as the verification of general relativity, the secular variations of the Sun’s mass and the gravitational constant, and the limits on the dark matter density in the Solar System. The EPM ephemerides, together with the corresponding time differences TT — TDB and the coordinates of seven additional objects (Ceres, Pallas, Vesta, Eris, Haumea, Makemake, and Sedna), are available at ftp://quasar.ipa.nw.ru/incoming/EPM. 相似文献
4.
E. V. Pitjeva 《Solar System Research》2005,39(3):176-186
The latest version of the planetary part of the numerical ephemerides EPM (Ephemerides of Planets and the Moon) developed at the Institute of Applied Astronomy of the Russian Academy of Sciences is presented. The ephemerides of planets and the Moon were constructed by numerical integration in the post-Newtonian metric over a 140-year interval (from 1880 to 2020). The dynamical model of EPM2004 ephemerides includes the mutual perturbations from major planets and the Moon computed in terms of General Relativity with allowance for effects due to lunar physical libration, perturbations from 301 big asteroids, and dynamic perturbations due to the solar oblateness and the massive asteroid ring with uniform mass distribution in the plane of the ecliptic. The EPM2004 ephemerides resulted from a least-squares adjustment to more than 317000 position observations (1913–2003) of various types, including radiometric measurements of planets and spacecraft, CCD astrometric observations of the outer planets and their satellites, and meridian and photographic observations. The high-precision ephemerides constructed made it possible to determine, from modern radiometric measurements, a wide range of astrometric constants, including the astronomical unit AU = (149597870.6960 ± 0.0001) km, parameters of the rotation of Mars, the masses of the biggest asteroids, the solar quadrupole moment J
2 = (1.9 ± 0.3) × 10−7, and the parameters of the PPN formalism β and γ. Also given is a brief summary of the available state-of-the-art ephemerides with the same precision: various versions of EPM and DE ephemerides from the Jet Propulsion Laboratory (JPL) (USA) and the recent versions of these ephemerides—EPM2004 and DE410—are compared. EPM2004 ephemerides are available via FTP at ftp://qua-sar.ipa.nw.ru/incoming/EPM2004.__________Translated from Astronomicheskii Vestnik, Vol. 39, No. 3, 2005, pp. 202–213.Original Russian Text Copyright © 2005 by Pitjeva. 相似文献
5.
E.V. Pitjeva 《Celestial Mechanics and Dynamical Astronomy》2001,80(3-4):249-271
The JPL planetary and lunar ephemerides – DE200/LE200, DE403/LE403, DE405/LE405 and the planetary and lunar ephemerides, EPM87, EPM98, and EPM2000, constructed in the Institute of Applied Astronomy of RAS are described. Common properties and differences of the various ephemerides are given. Graphical comparisons of the DE ephemerides with each other and with the EPM ephemerides are presented. A fairly good agreement of planetary orbits is between DE403, DE405 and EPM98, EPM2000, respectively, over the interval of 120 years (1886–2006) covered by EPM98 and EPM2000. Some differences are explained by a slight disagreement in representing the orbits of Ceres, Pallas, and Vesta as they affect the planets. The accurate radar observations of planets and spacecraft make it possible not only to improve the orbital elements of planets but to determine a broad set of astronomical constants as well: km/AU, parameters of Mars rotation including its precessional rate, the masses of Jupiter, Ceres, Pallas, and Vesta, relativistic parameters of the PPN formalism, the variability of the gravitational constant G. These have been obtained in the fitting process of the DE405 and EPM2000 ephemerides to observational data, including nearly 80000 American and Russian radar observations of planets (1961–1997), ranging and doppler to the Viking and Pathfinder landers, and other miscellaneous measurements from various sources and spacecraft. 相似文献
6.
Since 1984, the new IAU (1976) System of Astronomical Constants has become effective; meanwhile, the new lunar and planetary ephemerides (DE200/LE200) have been introduced into the Astronomical Almanac. In order to obtain the best fit of these ephemerides to the observational data, some modifications to the constants were made (Kaplan 1961). The modified values of these constants have been accepted by many users (particularly in the Merit Project), (Melbourne et al. 1983), although there has not been any new resolution of IAU. To avoid these inconsistencies, it seems to be necessary to rediscuss the adopted value of some astronomical constants in the new system. This paper discusses the problems for selection of the precession quantities and derives the precession expressions based on the motion of ecliptic from the DE ephemeris. 相似文献
7.
M. V. Vasilyev E. I. Yagudina E. A. Grishin O. A. Ivlev I. A. Grechukhin 《Solar System Research》2016,50(5):361-367
The potential effect of the future Russian lunar laser ranging system (LLRS) on the accuracy of lunar ephemerides is discussed. In addition to the LLRS in Altai, several other observatories suitable for the LLRS installation are considered. The variation of accuracy of lunar ephemerides in the process of commissioning of new LLRS stations is estimated by mathematical modeling. It is demonstrated that the error in the determination of certain lunar ephemeris parameters may be reduced by up to 16% after seven years of operation of the Altai LLRS with a nearly optimal observational program. 相似文献
8.
More than 70 new distant satellites of major planets have been discovered over the past five years. Until recently, the Jet Propulsion Laboratory (JPL) in the USA was the only institution that modeled the motion of these satellites based on observational data and computed their ephemerides. New independent computations are needed to ensure the reliability and to assess the accuracy of satellite ephemerides. In this paper, the results of our determination of orbital parameters for 73 new distant satellites of major planets based on all available observations are reported and the adopted model of perturbing forces acting on a satellite is described. The satellite motions are computed via numerical integration. A special program—an ephemeris server—is used to compute the ephemerides of satellites, which are freely available to any user on the Internet at http://lnfm1.sai.msu.ru/neb/nss/index.htm. The server offers ample choice in terms of the form and composition of the ephemerides produced. The paper gives examples of deviations of the theory from observations and comparisons of our results with JPL ephemerides. Standard deviations of observational results from the theory are equal to 0.3–0.5 for most of the satellites. A comparison of our models of the motion of satellites with those developed at JPL shows that deviations in topocentric coordinates do not exceed 0.01 over a six-year interval.__________Translated from Astronomicheskii Vestnik, Vol. 39, No. 2, 2005, pp. 128–140.Original Russian Text Copyright © 2005 by Emelyanov, Kanter. 相似文献
9.
V. Lainey 《Planetary and Space Science》2008,56(14):1766-1772
We have developed a new dynamical model of the main Uranian satellites, based on numerical integration and fitted to astrometric observations. Old observations, as well as modern and Voyager observations have been included. This model has provided ephemerides that have already been used for predicting the mutual events during the PHE-URA campaign. It is updated here to improve the prediction of these events. We also tried to assess the real accuracy of our ephemerides by checking the distance differences of the Uranian satellites, using simultaneously our former and new model. It appears that both solutions are very close to each other (within few tens of kilometers), and most probably accurate at the level of few hundred of kilometers. Using new available meridian observations of the Uranian satellites, we have checked the Uranian ephemeris accuracy using DE406. An error of more than 0.1 arcsec on the Uranian position is observed. 相似文献
10.
Aldo Vitagliano 《Celestial Mechanics and Dynamical Astronomy》1996,66(3):293-308
A simplified model of the solar system has been developed along with an integration method, enabling to compute planetary and lunar ephemerides to an accuracy better than 1 and 2 milliarcsecs, respectively. On current personal computers, the integration procedure (SOLEX) is fast enough that by using a relatively small ( 20 Kbytes/Cy) database of starting conditions, any epoch in the time interval (up to ±100 Cy) covered by the database can be reached by the integrator in a few seconds. This makes the algorithm convenient for the direct computation of high precision ephemerides over a time span of several millennia. 相似文献
11.
本文评述了在建立历表参考架和恒星参考架过程中所面临的问题和困难，回顾了建立河外射电天球参考架的发展历史，并介绍了其目前状况，讨论了河外射电天球参考架在与其他天球参考架连接过程中所遇到的问题及其可能的解决途径。 相似文献
12.
A. P. Baturin 《Solar System Research》2018,52(4):355-358
The discontinuous behavior of coordinates of planets and the Moon and their derivatives, which are determined from their modern ephemerides, at the boundaries of adjacent interpolation intervals is illustrated using the example of the DE436 ephemerides. The numerical integration of the equations of motion of two asteroids demonstrates that the integration accuracy increases by several orders of magnitude if the step of numerical integration is matched to the boundaries of ephemeris interpolation intervals. In addition, an algorithm for ephemeris smoothing at the boundaries of interpolation intervals is developed and applied in order to eliminate the jumps of coordinates and their first-order derivatives emerging in extended- and quadprecision calculations. This algorithm allows one to remove the jumps of coordinates and their derivatives up to any given order. It is demonstrated that the use of ephemerides smoothed to the first-order derivatives in quad-precision calculations increases the accuracy of numerical integration by ~10 orders of magnitude. 相似文献
13.
We determine new linear ephemerides of transiting exoplanets using long-cadence de-trended data from quarters Q1 to Q17 of the Kepler mission. We analysed transit-timing variation(TTV) diagrams of 2098 extrasolar planets. The TTVs of 121 objects were excluded(because of insufficient datapoints, influence of stellar activity, etc.). Finally, new linear ephemerides of 1977 exoplanets from the Kepler archive are presented. A significant linear trend was observed on TTV diagrams of approximately 35% of the exoplanets studied. Knowing the correct linear ephemeris is key for successful follow-up observations of transits. Residual TTV diagrams of 64 analysed exoplanets show periodic variation, and 43 of these TTV planets were not previously reported. 相似文献
14.
The satellite-borne GPS receivers dedicated to precise orbit determination are now being carried by more and more low earth orbit (LEO) satellites and the satellite-borne GPS has become one of the main means for the precise orbit determination of low earth orbit satellites. The accuracy of satellite-borne GPS precise orbit determination depends on the accuracies of the GPS ephemeris and the clock error. Based on the orbit determination function of SHORDEIII zero-difference dynamics and using the observational data obtained by the GRACE satellites for the week from 2005 August 1 to 7 as an example, three versions of GPS ephemerides (igs, igr and igu) are used to carry out orbit determination under the same conditions and to estimate the effect of the GPS ephemeris accuracy on the accuracy of orbit determination of low earth orbit satellites. Our calculated results show that the two ephemerides, igs and igr, are equivalent to each other in orbit determination accuracy (about 9.5 cm), while igu is slightly less accurate, at about 10.5 cm. The effect produced by the data of the high frequency GPS satellite clock error on the accuracy of orbit determination is 1–6 cm. 相似文献
15.
A. L. Poroshina 《Astronomy Letters》2013,39(12):876-881
The ephemerides of satellites of major planets are needed in planning spacecraft missions both for studying the satellites themselves and for navigational support during the flights of spacecraft in the vicinity of planets. In addition, accurate numerical theories of motion of the natural satellites of major planets make it possible to increase the accuracy of the ephemerides of their central planets based on positional (photographic and CCD) observations of the satellites. Numerical theories of Neptune’s satellites, Triton and Nereid, constructed within the framework of the ERA software package developed at the Institute of Applied Astronomy of the Russian Academy of Sciences are presented. 相似文献
16.
The relation between the synodic and sidereal rotation period of the Sun for an arbitrary date of observation is derived taking into account details of the Earth's motion. The transformation procedure between the synodic (apparent) and sidereal rotation period presented here can be performed without using the annual ephemerides. 相似文献
17.
This paper outlines the progress in development of the numerical planet ephemerides EPM—Ephemerides of Planets and the Moon. EPM was first created in the 1970s in support of Russian space flight missions and constantly improved at IAA RAS. Comparison between various available EPM ephemerides (EPM2004, EPM2008, EPM2011) is shown. The first results of the updated EPM2013 version which takes into account the two-dimensional annulus of small asteroids are presented. Currently two main factors drive the progress of planet ephemerides: dynamical models of planet motion and observational data, with the crucial role of spacecraft ranging. EPM ephemerides are the basis for the Russian Astronomical and Nautical Astronomical Yearbooks, are planned to use in the GLONASS and LUNA-RESOURCE programs, and are being used for determination of physical parameters: masses of asteroids, planet rotation parameters and topography, the \(GM_\odot \) and its secular variation, the PPN parameters, and the upper limit on the mass of dark matter in the Solar System. The files containing polynomial approximation for EPM ephemerides (EPM2004, EPM2008, EPM2011) along with TT–TDB and ephemerides of Ceres, Pallas, Vesta, Eris, Haumea, Makemake, and Sedna are available from ftp://quasar.ipa.nw.ru/incoming/EPM/. Files are provided in IAA’s binary and ASCII formats, as well as in the SPK format. 相似文献
18.
Xi-Liang Zhang Yong Yu Xue-Li Wang Chuan-Jun Wang Liang Chang Yu-Feng Fan Zheng-Hong Tang 《天文和天体物理学研究(英文版)》2015,(3):435-442
Under the framework of observational campaigns organized by the GAIA Follow Up Network for Solar System Objects, three near Earth asteroids, 367943 Duende, 99942 Apophis and 2013 TV135, were observed with the Lijiang 2.4 m telescope administered by Yunnan Observatories. The software package PRISM was used to calibrate the CCD fields and measure the positions of 99942 Apophis and2013 TV135, and our own software was used for 367943 Duende. A comparison of the results show that the ephemerides of INPOP10 a and JPL are consistent for99942 Apophis and 2013 TV135, however, they are quite inconsistent for 367943 Duende. Moreover, we have found that differences between the mean values in the ephemerides of INPOP10 a and JPL are about 72 and-199 in right ascension and declination respectively for 367943 Duende. Moreover, the ephemeris published by JPL is reliable in terms of the mean observed-minus-calculated(O- C) residuals in right ascension and declination of about 2.72 and 1.49 respectively. 相似文献
19.
20.
Neptune and Pluto were discovered because of predictions derived from the differences between the observations and ephemerides of Uranus, but Pluto wasn't the predicted planet and the discrepancies still exist. This continuing existence of systematic differences between the observations and ephemerides of Uranus and Neptune has led to predictions of a Planet X. The demise of the dinosaurs and the existence of comets have been cited as additional evidence for another celestial object.Therefore, possible bodies have been hypothesized in the outer part of the solar system, or out beyond the solar system, including a binary companion, Nemesis. The theory of relativity and the incompleteness of the law of gravity have also been suggested as explanations for the outer planet discrepancies. Predictions of the possible locations of planet X have been made, with rather large uncertainties, and selected searches of some regions have yielded nothing. IRAS and Pioneer observations exist as additional sources of useful observational data. 相似文献