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1.
In 2009, in five Russian observatories photometric observations of Jupiter’s Galilean satellites during their mutual occultations and eclipses were carried out. Based on these observations, an original method was used to ascertain astrometric results such as the difference between the coordinates of pairs of satellites. Fifty-three phenomena were successfully observed. A total of 94 light curves of satellites were measured. The error in the coordinates of satellites due to random errors in photometry, calculated on all data obtained, was 0.041″ in right ascension and 0.046″ in declination. The discrepancies between the theory and observations in these coordinates was found to be 0.060″ and 0.057″, respectively. The results were uploaded to the common database for all observations of natural satellites of planets at the Natural Satellites Data Center (NSDC), which is available online at http://www.sai.msu.ru/neb/nss/index.htm. For the first time in the practice of photometric observations of satellites in epochs of mutual occultations and eclipses a new method of observation was tested, which eliminates from astrometric results the major systematic errors caused by an inaccurate account of the background level. The tests were conducted in the Terskol Observatory and the observatory of the Crimean laboratory of the Sternberg State Astronomical Institute of the Moscow State University. The application of the new method showed that the elimination of the background level at these observatories was carried out correctly.  相似文献   

2.
Noteworthy phenomena, viz., mutual occultations and eclipses in the system of Jupiter’s Galilean satellites and in the system of Saturn’s principal satellites, will occur in 2009. The relatively simple photometry of these phenomena makes it possible to obtain positional data at a higher accuracy than can be achieved in regular astrometric observations. The visibility conditions for the satellites are described here and observational recommendations are given. The ephemerides of these phenomena are available via the Internet from the MULTI-SAT ephemerides server at http:/www.sai.msu.ru/neb/nss/index.htm.  相似文献   

3.
A new database of all astrometric observations of moons of asteroids is offered. It has a simple structure and is accessible through the Internet. Regular database updating is provided when new observational results occur in publications. The database is located at the sites of the Natural Satellites Data Center created as a result of collaboration between the Sternberg Astronomical Institute of Moscow State University and the Institut de Mécanique Céleste et de Calcul des Ephémérides (IMCCE). The database addresses in the Internet are https://doi.org/www.sai.msu.ru/neb/nss/indexr.htm and https://doi.org/nsdb.imcce.fr/obsposrespectively. On entering these sites, we need to select one of three languages, the Observation item, and the Astrometric positions of asteroids with moons item. The observational data are provided here with explanations and hyperlinks to the publications in the bibliographic database SAO/NASA Astrophysics Data System (ADS) Abstract Service.  相似文献   

4.
This study of the orbital evolution and encounters of distant satellites of planets is aimed at determining their origin. It is also important for understanding the distribution of matter in the early stages of evolution of the Solar System. The mutual encounter of satellites is very weak because of their small sizes and masses. However, at very large time intervals, mutual encounter can be quite close to significantly changing the orbits of satellites. In order to study these factors, we have developed a special method and computer programs. For 107 distant satellites of Jupiter, Saturn, Uranus, and Neptune, motion parameters have been determined using observational data. On the basis of these parameters, a numerical integration of the equations of motion of the satellites has been carried out in time intervals of several thousand years. Using the original method of frequency analysis, we found rather simple analytical functions that correspond to the results of the numerical integration and make it possible to calculate orbital parameters at any time during a long interval. These tools make it possible to conduct extensive studies of changes in the form and relative position in space of the orbits of distant satellites of Jupiter, Saturn, Uranus, and Neptune. Several examples illustrate the possibilities offered by these tools. The computer software in the form of a service ephemeris of satellite orbits over a long interval of time is available via the Internet (http://www.sai.msu.ru/neb/nss/evolu0e.htm) on the website of the State Astronomical Institute of the Moscow State University.  相似文献   

5.
A catalog of 1385 astrometric positions of Saturn’s moons S2–S9 has been compiled with Tycho-2 as a reference frame from photographic observations obtained at the Main Astronomical Observatory, National Academy of Sciences of Ukraine, in 1961–1990. Astronegatives have been digitized with an Epson Expression 10000XL commercial scanner in 16-bit grayscale with a resolution of 1200 dpi. Reduction has been performed in the LINUX-MIDAS-ROMAFOT software supplemented with additional modules. The internal positional accuracy of the reduction is 0.09…0.23′′ for both coordinates and 0.27…0.37m for the photographic magnitudes of the Tycho-2 catalog. The calculated topocentric positions of the moons are compared online with the IMCCE ephemeris data (DE405 + TASS1,7). Moon-minus-moon differential coordinates are found for most of the moons and compared with theoretical data (http://lnfm1.sai.msu.ru/neb/nss/nssephmr.htm).  相似文献   

6.
We provide an overview of the main results obtained as part of the programs for astrometric observations of bodies in the Solar system at the Pulkovo Observatory over the period 1898–2005. We summarize the results of photographic observations and show new possibilities for astrometric observations in connection with the transition to CCD detectors on Pulkovo instruments. Observing and data reduction techniques are considered. A database with Pulkovo observations of bodies in the Solar system has been created and opened to users. The database is accessible at http://www.puldb.ru.  相似文献   

7.
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   

8.
The results of astrometric observations of Saturn’s satellites (S1–S8) obtained using a 26-inch refractor and a normal astrograph at Pulkovo Observatory in 2004–2007 are given. High-accuracy equatorial coordinates of Saturn’s satellites in the system of the UCAC2 reference catalog and the relative “satellite-satellite” positions suitable for specifying their motion theories are obtained. The observations are compared with the DE405 + TASS1.7 and INPOP06 + TASS1.7 theories of motion. The root-mean-square errors of the obtained satellite positions lie within the range of 10–50 mas, as far as the intrinsic convergence is concerned, and 20–70 mas, as far as the extrinsic one is concerned. The observation results are included into the astrometrical database of the Pulkovo Observatory (www.puldb.ru).  相似文献   

9.
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   

10.
The sets of photographic observations of the Galilean satellites of Jupiter taken at the Abastumani Astrophysical Observatory of the Academy of Sciences of Georgia are analyzed here. Positional observations of the system of Jupiter were made in the period from 1985 to 1994 with the use of the double Zeiss astrograph in order to determine the exact coordinates of Jupiter and its satellites. The accurate positions of the satellites and Jupiter itself, as well as their stellar (equatorial) coordinates relative to the stars of the currently available catalogs and the relative ??satellite ?? satellite?? coordinates were obtained from the observations. From the comparison of the observation results with the modern theories of motion of satellites, the accuracy in determining the positions of the satellites and Jupiter was analyzed. The results of observations are presented in the Pulkovo database of observations of Solar System bodies that is accessible to users at http://www.puldb.ru.  相似文献   

11.
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   

12.
We describe the GOCK-2005 catalog (Geosynchronous Objects Catalog: Kyiv) which contains the topocentric equatorial coordinates and orbital elements of geosynchronous satellites obtained by the photographic technique at the Main Astronomical Observatory NASU in 2002 (http://www.mao.kiev.ua/ast/astron.htm). On the whole, there are 176 observations of 57 objects, among which 20 objects were identified from 98 observations.  相似文献   

13.
The He, C, N, and O abundances in more than 120 planetary nebulae (PNe) of our Galaxy and the Magellanic Clouds have been redetermined by analyzing new PNe observations. The characteristics of PNe obtained by modeling their spectra have been used to compile a new catalog of parameters for Galactic and extragalactic PNe, which is accessible at http://www.astro.spbu.ru/staff/afk/GalChemEvol.html. The errors in the parameters of PNe and their elemental abundances related to inaccuracies in the observational data have been analyzed. The He abundance is determined with an accuracy of 0.06 dex, while the errors in the C, N, and O abundances are 0.1–0.2 dex. Taking into account the inaccuracies in the corrections for the ionization stages of the elements whose lines are absent in the PNe spectra increases the errors in the He abundance to 0.1 dex and in the C, N, and O abundances to 0.2–0.3 dex. The elemental abundances in PNe of various Galactic subsystems and the Magellanic Clouds have been analyzed. This analysis suggests that the Galactic bulge objects are similar to type II PNe in Peimbert’s classification, whose progenitor stars belong to the thin-disk population with ages of at least 4–6 Gyr. A similarity between the elemental abundances in PNe of the Magellanic Clouds and the Galactic halo has been established.  相似文献   

14.
Many papers are devoted to the prediction of radiation conditions on board of a spacecraft (Pichkhadze et al., 2004; Khamidullina et al., 2008; 2012), and a number of software systems for corresponding calculations have been developed: the US information system CREME96 (https://creme.isde.vander-bilt.edu/); European SPENVIS (http://www.spenvis.oma.be/intro.php); Russian SEREIS (Kuznetsov et al., 2001; Model’ kosmosa, 2007) and COSRAD (http://cosrad.sinp.msu.ru/manual.html; Kuznetsov et al., 2011) based on the models of the radiation environment in near-Earth space (Bashkirov et al., 1998; Nymmik, 2004; Model’ kosmosa, 2007; Kuznetsov et al., 2011). In this paper we propose a simple calculation algorithm of short-term (for a few days) forecasting of dynamics of the radiation dose on the International Space Station (ISS) in radiation environment undisturbed by solar proton events. This algorithm does not use radiation environment models and detailed ballistic calculations, while it uses data of the onboard radiation monitoring system (RMS) and empirical relations, obtained for ISS orbital motion.  相似文献   

15.
We suggest a new approach and develop an original method for deriving astrometric data from the photometry of mutual occultations and eclipses of planetary satellites. We decide to model not the relative apparent motion of one satellite with respect to another satellite but the deflection of the observed relative motion with respect to the theoretical motion implied by appropriate ephemerides.We have attempted to reduce the results of photometric observations of the Gallilean satellites during their mutual occultations and eclipses in 2002-2003. The data of observation for 319 light curves of 106 mutual events were received from the observers. The reliable 245 light curves were processed with our method. Eighty six apparent relative positions have been obtained.Systematic errors arise inevitably while deriving astrometric data. Most of them are due to factors that are unrelated to the methods for deriving astrometric data. The systematic errors are more likely due to incorrect excluding the effect of background on photometric counts. In the case of mutual occultations, the flux drop is determined to a considerable degree by the ratio of the mean albedos of the two satellites. Some mutual event observations revealed wrong adopted values of the mean albedos.  相似文献   

16.
Tidal dissipation is the main driver of orbital evolution of natural satellites and a key point to understand the exoplanetary system configurations. Despite its importance, its quantification from observations still remains difficult for most objects of our own Solar System. In this work, we overview the method that has been used to determine, directly from observations, the tidal parameters, with emphasis on the Love number \(k_2\) and the tidal quality factor Q. Up-to-date values of these tidal parameters are summarized. Last, an assessment on the possible determination of the tidal ratio \(k_2/Q\) of Uranus and Neptune is done. This may be particularly relevant for coming astrometric campaigns and future space missions focused on these systems.  相似文献   

17.
The photometry of mutual occultations and eclipses of natural planetary satellites can be used to infer very accurate astrometric data. This can be achieved by processing the light curves of the satellites observed during international campaigns of photometric observations of these mutual events.
This work focuses on processing the complete data base of photometric observations of the mutual occultations and eclipses of the Galilean satellites made during the international campaign in 2002–2003. The final goal is to derive new accurate astrometric data.
We propose the most accurate photometric model of mutual events based on all the data available to date about the satellites, and develop the corresponding method for extracting astrometric data. This method is applied to derive astrometric data from photometric observations of mutual occultations and eclipses of the Galilean satellites.
We process the 371 light curves obtained during the international campaign of photometric observations of the Galilean satellites in 2002–2003. As compared with the theory, the rms 'O-C' residuals with respect to theory is equal to 0.055 and 0.064 arcsec in right ascension and declination, respectively, for the 274 best observations. Topocentric or heliocentric angular differences for satellite pairs are obtained for 119 time instants during the time period from 2002 October 10 to 2003 July 17.  相似文献   

18.
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   

19.
We have obtained numerically integrated orbits for Saturn's coorbital satellites, Janus and Epimetheus, together with Saturn's F-ring shepherding satellites, Prometheus and Pandora. The orbits are fit to astrometric observations acquired with the Hubble Space Telescope and from Earth-based observatories and to imaging data acquired from the Voyager spacecraft. The observations cover the 38 year period from the 1966 Saturn ring plane crossing to the spring of 2004. In the process of determining the orbits we have found masses for all four satellites. The densities derived from the masses for Janus, Epimetheus, Prometheus, and Pandora in units of g cm−3 are , , , and , respectively.  相似文献   

20.
Since 1998, 97 new remote satellites of Jupiter, Saturn, Uranus, and Neptune have been discovered. Since their brightness is rather weak, it is difficult to perform their photometry and determine their physical parameters. For 27 satellites from this group, different authors carried out special photometric investigations. For the other 70 satellites, the magnitudes accompanying the results of astrometric observations published in Minor Planet Circulars (MPC) are the only photometric data. In the present study, the photometric model parameters for all of the 97 remote satellites have been determined. From the hypothetic values of albedo and material density of the satellites, their sizes and gravitation parameters have been estimated. The whole volume of the obtained results is available in the database of the natural planetary satellites (NSDB) (Arlot and Emelyanov, 2009) published on the Internet ().  相似文献   

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