In 1997 the Sun and the Earth passed through the equatorial plane of Jupiter and therefore through the orbital planes of its main satellites. During this period, mutual eclipses and occultations occurred and were observed. We investigate the precision of the catalogue to produce improved data for the development of dynamical models. Light curves of mutual eclipses and occultations were recorded by the observers of the international campaign PHEMU97 organized by the Institut de Mecanique Celeste, Paris, France. We made 275 observations of 148 mutual events from 42 sites. For each observation, information is given about the telescope, the receiver, the site and the observational conditions. This paper gathers together the data and gives a first estimate of the precision. The catalogue of these rare events represents a collection of improved accurate astrometric data useful for the development of dynamical models.

In 1994-1996 the Sun and the Earth passed through the equatorial plane of Saturn and therefore through the orbital planes of its main satellites. During this period, phenomena involving seven of these satellites were observed. Light curves of eclipses by Saturn and of mutual eclipses and occultations were recorded by the observers of the international campaign PHESAT95 organized by the Institut de mecanique celeste, Paris, France. Herein, we report 66 observations of 43 mutual events from 16 sites. For each observation, information is given about the telescope, the receptor, the site and the observational conditions. This paper gathers together all these data and gives a first estimate of the precision providing accurate astrometric data useful for the development of dynamical models.

Depuis 1985, un supplement a Ia Connaissance des Temps est publie et donne Ies positions des satellites de Mars, des satellites galileens de Jupiter, des huit premiers satellites de Saturne et des cinq satellites d'Uranus sous forme de fonctions mixtes avec une precision proche des theories originales. Une disquette pour micro-ordinateur accompagne cet ouvrage. Cependant, des observateurs ont souhaite continuer a disposer d'un ouvrage permettant d 'identifier Ies satellites galileens et de connaitre Ies instants des phenomenes presentes par ces satellites et calcules a une seconde de temps pres. C'est ce que donne Ie present fascicule. En particulier, Ies configurations precises permettent tres facilement de situer Ies satellites avec une precision de 10 par rapport a Jupiter. On trouvera de plus des renseignements generaux sur Ies satellites galileens en debut d'ouvrage ainsi qu'une methode de calcul des phenomenes pour l'annee suivante en fin d'ouvrage

From 1992 to 1999, the satellites of Saturn are involved in several phenomena: eclipses or occultations by the planet, transits in front of Saturn, or transits of their umbra. These phenomena occur thanks to the geometrical circumstances in 1995 when the Earth and the Sun went through the plane of the Saturnian ring and consequently through the orbital planes of the main satellites. These circumstances are also favorable to the observation of mutual phenomena occurring when the satellites eclipse or occult each other. These mutual phenomena and the eclipses by Saturn are rare as they occur only every 15 years. But, they are very useful to get highly accurate astrometric observations and they allowed us to estimate some physical parameters. We have organized the PHESAT95 campaign to observe these phenomena and a special effort was made to observe as many events as possible. At the present time, the observations are still being collected from different teams and different countries; this paper shows the first results which have been obtained in several sites, and the first comparison with the theory of the motions.

In this paper, all the usable light curves obtained during the PHEMU85 campaign of observations of the mutual phenomena of the Galilean satellites are presented. These observations will provide accurate astrometric positions of major interest for dynamical studies of the motion of the Galilean satellites. The aim of this work is to give observational data directly usable for theoretical studies. We made 166 observations of 64 mutual events from 28 sites. The corresponding data are given in the present paper and compared with the theoretical predictions. The accuracy of each observation has been determined. For each observation, information is given about the telescope, the receptor, the site and the observational conditions.

In 1991 we organized a campaign of observation of mutual eclipses and occultations between the Galilean satellites. This paper presents the results obtained at the European Southern Observatory from the observation of mutual events involving Io. We analyze the infrared observation of the occultation of Io by Europa made with a 1-m telescope of February 20, 1991. During the observation of this occultation two volcanoes were occulted by Europa and their signatures have been recorded at 3.8 μm. The same observation was simultaneously made with the ESO 50-cm telescope with the v Strömgren filter. We used this to derive corrections for the ephemerides during the event thanks to a fit of a new photometric model and also to obtain measurements of the positions of hotspots on Io's visible surface. Similarly, a model including the thermal emission of the volcanoes permits a close representation of the infrared lightcurve and provides physical parameters related to the two volcanoes Loki and Pele.

Presentation des techniques qui seront utilisees pour observer les occultations et les eclipses mutuelles des satellites galileens en 1991

Depuis -1980, Ia Connaissance des Temps publie Ies ephemerides du Soleil, de Ia Lune, des planetes et des satellites Galileens de Jupiter sous forme de coefficients de Tchebycheff. A partir de 1981, des ephemerides des huit premiers satellites de Saturne ont ete publiees sous Ia meme forme dans un supplement a Ia Connaissance des Temps. Ces ephemerides ayant ete appreciees par Ies utilisateurs, nous avons decide d’etendre ces publications a d’autres satellites naturels du Systeme Solaire. Depuis 1985, nous publions dans un meme recueil des ephemerides des satellites Galileens de Jupiter, des huit premiers satellites de Saturne et des cinq satellites d’Uranus. Les ephemerides ne sont plus representees a l’aide de coefficients de Tchebycheff, mais a l’aide de fonctions mixtes du parametre «temps » comprenant des termes seculaires et des termes periodiques. Cette representation permet de garder une bonne precision tout en diminuant notablement Ie nombre de valeurs numeriques a publier et en autorisant une plus grande facilite d'emploi. La liste des satellites dont nous publions Ies ephemerides n’est pas limitative et nous envisageons de l’etendre en fonction des donnees dont nous disposerons. En dehors des ephemerides proprement dites cet ouvrage contient des donnees diverses sur Ies satellites de Jupiter, Saturne et Uranus et presente un formulaire permettant de calculer Ies phenomenes des satellites Galileens de Jupiter

In Dynamical Astronomy, the data used to fit theories are positional observations. If the data are reduced using computers, the measure itself is not, and informations are lost. The classical way is to use photographic plates measured by hand. The use of automatic machine permits to save time but not to increase the amount of data.