Old astrophotographic plates are precious sources of historical data for astronomical studies, especially regarding the improvement of natural satellite orbits. Today, with the advent of new, accurate techniques, these old data can be re-processed so as to give positions that are much more accurate than those initially obtained. Various recent projects, including our Chinese project, have involved measuring and reducing these old plates again. Here we present a method for measurement and reduction that involves the digitization of plates using an advanced commercial scanner, namely the EPSON 10000 XL. We selected a set of 27 plates of the satellites of Jupiter, Saturn and Uranus taken from 1987 to 1990. A total of 125 satellite positions were derived from the new measurement and reduction of these plates using the UCAC4 catalogue. A comparison of the new observed positions with recent ephemerides has shown a general consistency with satellite theory of about 100 mas. The new positions present an accuracy equivalent to the most recent CCD observations, and better than the original positions. Moreover, nearly 30 per cent of the 125 positions obtained in this work are published for the first time here. This paper is a preliminary contribution to the larger project of new measurements and reductions of all the old Chinese plates of natural satellites, which should allow further improvements in the knowledge of the orbits of these satellites.

We used 3108 Earth-based astrometric observations from the Natural Satellite Data Center (NSDC) over more than 30 years time span from 1975 to 2006 for determining the epoch state vectors of the Neptunes largest satellite Triton. In integrating the perturbation equation, the barycentric frame of Neptune-Triton system is adopted, and in considering the oblateness perturbation due to Neptune, a revised pole model describing the precession of the Neptune's pole is used in our calculation. Moreover, a total of 1095 new observed positions of Triton were collected during 46 nights of observations in 2007, 2008 and 2009. We compared our observations to two ephemerides of Triton and most of the available planetary ephemerides of Neptune.

In this paper, we used the 3108 Earth-based astrometric observations from the Natural Satellite Data Center over more than 30 yr time span from 1975 to 2006 for determining the epoch state vectors of the Neptunian largest satellite Triton.These observations almost contain all modern photo and CCD observations available.In integrating perturbation equation, the barycentric frame of Neptune-Triton system is adopted, and in considering the oblateness perturbation due to Neptune, a revised pole model describing the precession of the Neptune's pole is used in our calculation.

Context. In 2009, the Sun and the Earth passed through the equatorial plane of Jupiter and therefore the orbital planes of its main satellites. It was the equinox on Jupiter. This occurrence made mutual occultations and eclipses between the satellites possible. Experience has shown that the observations of such events provide accurate astrometric data able to bring new information on the dynamics of the Galilean satellites. Observations are made under the form of photometric measurements, but need to be made through the organization of a worldwide observation campaign maximizing the number and the quality of the data obtained.

Astrometric positions of the Neptunian satellite Triton with a visual magnitude of 13.5 were obtained during three successive oppositions in 2007, 2008 and 2009. A total of 1095 new observed positions of Triton were collected during 46 nights of observations, involving eight missions and three telescopes. We compared our observations to the best ephemerides of Triton available now. This comparison has shown that our observations present a high level of accuracy as they provide standard deviations of residuals hardly higher than 50 mas and mean residuals lower than 30 mas, corresponding to about only 500 km in the position of the very distant satellite Triton. Moreover, we have compared most of the different planetary ephemerides of Neptune available now as well as two recent orbit models of Triton. These new comparisons have clearly shown the differences between all of these ephemerides which can be significant and that are presented in this work.

Context. 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.Aims. This work focuses on processing the complete database of photometric observations of the mutual occultations and eclipses of the Saturnian satellites made during the international campaign in 2009. The final goal is to derive new accurate astrometric data.Methods. We develop an accurate photometric model of mutual event observations of sufficiently high accuracy. Our original method is applied to derive astrometric data from photometric observations of the mutual occultations and eclipses of the Saturnian satellites.Results. We process the 26 light curves obtained during the international campaign of photometric observations of the Saturnian satellites in 2009. Compared with the theory TASS 1.7 by Vienne and Duriez, we find that the root mean square of the "O-C" residuals for the 23 highest quality observations are equal to 48.5 and 21.7 mas in right ascension and declination, respectively, we obtain 16.4 and 20.7 mas with the new theory by Lainey and collaborators and 17.3 and 21.6 mas with JPL SAT351 ephemerides. Topocentric or heliocentric angular differences for satellites pairs are obtained for 16 time instants during the time period from December 19, 2008 to July 16, 2009.

Context. 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. Aims. This work focuses on processing the complete database of photometric observations of the mutual occultations and eclipses of the Uranian satellites made during the international campaign in 2007. The final goal is to derive new accurate astrometric data. Methods. We used an accurate photometric model of mutual events that explicitly depends on parameters that these accurate observations should be sensitive to, including the albedos of the satellites. Our original method is applied to derive astrometric data in relative positions from photometric observations of mutual occultations and eclipses of the Uranian satellites. Results. We process the 41 light-curves obtained during the international campaign of photometric observations of the Uranian satellites in 2007. The root-mean-square (rms) of the residuals “observations minus calculations” (O‐C) with respect to theory for the best 34 observations are equal to 10.3 and 17.7 mas in right ascension and declination, respectively. For five observations only the position angle was derived. Topocentric or heliocentric angular differences for satellites pairs were obtained from 25 central instant offsets between observation and theory during the time period from May 4, 2007 to January 4, 2008. Conclusions. The rms of the residuals is from 10 to 20 mas that corresponds in situ to 10 to 20 km. These mutual event observations appear to be the most accurate astrometric ground-based observations of the major Uranian satellites to-date and should be used for dynamical purposes.

We develop an accurate photometric model of mutual event observations of sufficiently high accuracy. Our original method is applied to derive astrometric data from photometric observations of the mutual occultations and eclipses of the Saturnian satellites. We process the 26 light curves obtained during the international campaign of photometric observations of the Saturnian satellites in 2009. (3 data files).

An observational campaign of the five Uranian major satellites was carried out during the period 1998-2007. A total of 2358 satellite observations in 1025 CCD frames were taken at two observational stations near Beijing and Shanghai with two telescopes of 0.8 and 1.56 m diameter. The observed positions were compared to the two Uranian satellites' recent ephemerides GUST06 and LA06. The result of this comparison has shown that the accuracy of our observations is about 100 mas for all the satellites. The satellite theories GUST06 and LA06 appear to be quite reliable for the first four satellites, with an accuracy of about 50 mas, but for Miranda the accuracy is only about 200 mas. Moreover, we have found a systematic error between the two planetary ephemerides DE405 and DE421 of about 80 mas for the period of our observations.

In recent years, many new CCD observations of Phoebe, the ninth Saturnian satellite, were published. In this paper, we have used all the observations of Phoebe available until 2009 to update Phoebe's orbit. These observations represent a total number of 2994 positions, spread over a time-interval of 105 years, from 1904 to 2009. The accuracy of the updated orbit of Phoebe presented here has been improved to about 0.1 arcsec as it has been fitted to a large number of new high-accuracy observations. However, the accuracy of the orbit remains limited by the accuracy of the observations. Moreover, we have shown that the new orbit is in quite good agreement with the very reliable JPL ephemeris, within less than 20 mas.

Astrometric observations of Phoebe, the faint ninth satellite of Saturn, with a visual magnitude of 16.5, were performed during four successive oppositions in 2005, 2006, 2007 and 2008. A total of 1173 new observed positions of Phoebe, representing more than 50 per cent of the observational data now available, were obtained during 30 nights of observation involving six missions and three telescopes. A comparison of our observed positions with the JPL Phoebe ephemeris shows the high quality of our observations, which have an accuracy of about 100 mas. Moreover, our observations appear to be consistent with this ephemeris within only about 50 mas.

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Context. In 2003, the Sun and the Earth passed through both the equatorial plane of Jupiter and therefore the orbital planes of its main satellites.Aims. During this period, mutual eclipses and occultations were observed and we present the data collected.Methods. Light curves of mutual eclipses and occultations were recorded by the observers of the international campaign PHEMU03 organized by the Institut de mecanique celeste, Paris, France.Results. We completed 377 observations of 118 mutual events from 42 sites and the corresponding data are presented in this paper. For each observation, information about the telescope, receptor, site, and observational conditions are provided.Conclusions. This paper gathers all data and indicates a first estimate of its precision. This catalogue of these rare events should constitute an improved basis for accurate astrometric data useful in the development of dynamical models.

In this paper, we present 112 new CCD astrometric positions of Nereid, the second and faint satellite of Neptune (mv � 19). We observed this small satellite in the 2006–2007 period with the 1 and 2.16-m telescopes of Xinglong Station near Beijing, both equipped with large CCD detectors of 1340 × 1300 and 2080 × 2048 pixels, respectively. The high density and highly accurate star catalogue UCAC2 was used in the reduction so that a classical astrometric calibration method was applied. We have shown that our observations of Nereid appear to be of equal or higher precision (σ � 0.2 arcsec) than most of the recent CCD ones.

Nous presentons dans cette Note Scientifique et Technique les resultats des observations astrometriques d'objets du systeme solaire effectuees de 1995 a 2007 avec la lunette meridienne CCD automatique de l'Observatoire de Bordeaux. Sur cette periode, nous avons effectue pres de 900 observations de planetes et satellites et plus de 1600 observations d'asteroides. Une analyse des observations des planetes et des satellites par Arlot et al. (2008) a montre leur utilite pour l'etude des ephemerides de ces corps.