REPORT OF THE WORKING GROUP ON SATELLITES FOR THE PERIOD JULY 1984 - JUNE 1987 (J.E. Arlot) I - OBSERVATIONS WITH ASTROMETRIC PURPOSE. a). Photographic observations: USNO ; Washington D.C.: D. Pascu continued photographic observations with the 26-inch telescope in washington, D.C. of the satellites of Mars, the Galilean satellites of Jupiter and saturn satellites I-VIII. Leander Mc Cormick (Charlotesville and Yale-Columbia (Mt Stromlo): During the three yars 1984 thru 1986 were obtained approximately 30 photographic exposures per year of the brighter satellites of Saturn an Naptune, and approximately 60 exposures per year for the Uranian and Jovian systems. The plates have been measured and the measurements have been transmitted to JPL. This observational program was now ended. Bordeaux Observatory (France):About 70 plates exposures of the Saturnian satellites I-VIII have been taken with the 14-incles refracter by Dourneau, G., Dulou, M.R. and Le Campion, J.F. in 1981 and 1982 published in Astron. Astrophys.. 142, 91 (39.1000.001). La Silla, ESO (Chile): 95 plates exposures of the Saturn satellites I-VIII have been taken withe the 1,50m danish reflector in 1981 published by Dourneau, G., Veillet C., Dulou M.R., Le Campion J.F. in 1986 in Astronomy Astrophysic. 160, 280 (41.100.016). Royal Greenwich observatory: Obsevations of Saturnian satellites made by Taylor and Sinclair in 1978, 1982 and 1983 were published in Astronomy Astrophysic Supp. Series 61, 221, 1985 (40.100.004). Pulkovo Observatory: The Galilean satelllites of Jupiter were observed in August-December, 1986 with the 26"astrograph (F=10.4m)and with the normal astrograph (F=3.4m). 35 plates were taken. The party of the Pulkovo observers carried out observations at Ordubad withe the lunar planet telescope (D=0.7m, F=10.0m). 108 plates with the Galilean satellites were taken in 1984, 1985 and 1986. In June-August 1986 60 plates with Phobos and Deimos were obtained using the same instrument. The greater part of the observations has been processed. S.V. Tolbin published results of observations of Mars and its satellites made with the 26" refractor in 1982 (Izv. Glav. Astron. Obs. Pulkovo N 203, 44-49, 1985 ; R. Zh. 2.51.123 (1986). He published also the results of observations of the Saturn's satellites with the 26" refractor in 1975 (40.1000.006). Nikolaev observatory: 36 plates with the Galilean satellites and 22 plates with Saturn's satellites were taken using the zone astrograph (D=0.26m, F=2.04m). V.I. Voronenko and G.K. Gorel'published observations of satellites of Jupiter and Saturn at Nikolaev in 1980-1982 (R. Zh. 12.51.112 (1986). Goloseevo observatory: 60 observations of Deimos made with astrograph (D=0.4m, F=5.5m) in 1980 were published by E.M. Sereda (R.Zh. 10.51.85 (1986)(42.097.026). Engelhardt Observatory: 202 observations of six satellites of Saturn obtained with the astrograph (D=0.4m, F=3.8m) in January-May 1980 were publishe by V.N. Kitkin and I.G. Chugunov (41.100.053). V.N. Kitkin published 41 positions of S III, S VI and S VIII obtained in February-March 1982 with 16" astrograph (R.Zh.10.51.91 (1986)). He also published results of 177 observations of Saturn's satellites made at the Engelhardt observatory using 16" astrograph and at its south sation at Zelenchuk using the astrograph (D=0.4 m, F=2.0m) in 1982-1984 (41.100.058). Observations of Miranda were made and published by Viera-Martins, Veiga and Lazzaro in Revista Mexicana de Astronomia e Astrofisica, 12, 427 (1986) (41.101.061) and a paper concerning the Image Processing Techniques for Position measurements of Uranus' satellites was published by Viera Martins, Carvallo and Veiga in Revista Mexicana de Astronomia e Astrofisica, 12, 399 (1986). b). CCD Observations. D. Pascu and P.K. Seidelmann continued observations with the Mark IV CCD Camera of the Space Telescope Widerfield Planetary Camera Team on the 61-inch telescope at Flagstaff, Arizona. Observations haveen made of Jupiter XIV, Saturn XII, XIII and XIV, Uranus I - V and Neptune I and II. These observations have been made annually and are both astrometric and photometric observations of these satellites (39.101.021, 41.101.033). c). Photometric observations : Aksnes and Franklin (Icarus 60, 180, 1984 (38.099.034), Sky and Telescope 69, 116, 1985, Arlot (Astronomy and Astrophysic 138, 113, 1984 (38.099.016) and Arlot and Rocher (Astronomy and Astrophysic Syppl. Series 58, 453, 1984 (38.099.115)) published predictions for some 300 mutual events of the Galilean Satellites in 1985-86 and contributed to a world-wide observing program of at least 130 events. First results were published by Arlot et al. in Suppl‚ment aux annales de Physiques, 12, fasc.1, 1987 and in The Messenger, 45, 13, 1986 (42.099.024); by Allen and Budding in Earth, Moon and Planets, 35, 73, 1986 (41.099.058), by Coulson in MNASSA, 45,77, 1986 and by Z.N. Grigor'eva, Yu.A. Egorov, V.G. Tejfel' and G.A. Kharitonova who observed at the Observatory of the Astrophysical Institute (Ashkhabad) in July and in September-October 1985 ("Astron. Tsirk.", 1986, N 1444, 1-3 ; R.Zh.6.51.95 (1987), "Astron. Tsirk.", 1986, N 1447, 3-5 ; R.Zh. 6.51.96 (1987)). Aksnes, Franklin and Magnusson in 1986 in Astron. J., 92, 1436 (42.099.068) traced the source of a puzzling longitude discrepancy between pairs of mutual eclipses and occultations occuring close in time, to the phase defects on the satellites. Mutual events of Pluto-Charon system were predicted for 1986 and 1987 (Tholen, 1985, in Astron. J., 90, 2639 (40.101.051) and Tholen, Buie and Swift, 1987, in Astron. J. 93, 244) and observed by Binzel, Tholen, Tedesco, Buratti and Nelson (Science, 228, 1193, 1985 (39.101.021)). A model for the eclipse events was given by Dunbar and Tedesco in the Astron. J., 92, 1201, 1986 (42.101.054). An asymetry appearing between eclipses and occultations was studied by Mulholland and Gustafson in 1987 (Astron. Astrophys., 171, L5). d.) Other observations. In two pages by Lieske (Astron. Astrophys. 154, 61, 1986, 41.099.001 and Astron. Astrophys. Supp. Series 63, 143) a collection of galilean satellites eclipse observations made since 1651 is presented. II - COMPARISON OF OBSERVATIONS WITH THEORIES; a.) Galilean satellites of Jupiter. In 1984, Arlot, Morando and Thuillot analyse recently rediscovered eclipses of J I made between 1775 and 1802 and collected by Delambre (Astron. Astrophys., 136, 142, (38.099.003)). Heliometer observations made from 1891 to 1906 were compared with moderm ephemerides (Arlot, 1986, Astron. Astrophys. 167, 371 (42.099.046)). Observations of occultations by Jupiter were analysed (fairhead, Arlot and Thuillot, 1986, Astron. Astrophys. 169, 360 (42.099.048) and catalogued (Fairhead, Arlot, Jannot and Thuillot, 1987, Astron. Astrophys. Suppl. Series, 68, 81). In two papers by Lieske, the evolution of the Galilean Satellites (tidal perturbations and secular changes in mean motions) is studied and observational evidence from a large set of data is shown ("Relativity in Celestial Mechanics and Astrometry", Brumberg and XXX eds, 117 in 1986, and Astron. Astrophys. 176, 146 in 1987). In the paper by Kiseleva, observations made at Pulkvo in 1904-1910 are analysed (Izv. Glav. Astron. Obs. Pulk. Astron. Astrofiz., 201, 71 (39.099.089). In the paper by T.P. Kiseleva, N.I. Glebova and A.G. Mal'Kova over 600 positions of the Galilean Satellites obtained at the Pulkovo observatory in 1975-1979 are compared with the Sampson's theory and with the Lieske's EI theory. The standard deviation of observed relative positions does not exceed O"10 (41.099.004). b.) Satellites of Saturn. In the series of papers by T.K. Nikol'skaya, Yu. V. Batrakov and T.K. Nikol'skaya the improvement of orbits of Saturn's satellites I - VII is fulfilled on the base of modern photographical observations. The perturbations of S I and S II were taken into account by the Struve theory, those of S III, S IV and S V by the Sinclair theory and the numerical theories were developed for S VI and S VII. New values of parameters of the theories were found for S I - S V and osculating elements of S VI and S VII were obtained for certain epoch (Buyll. Inst. Theor. Astron., 15, N 9, 534-537 ; R. ZH. 9.51.110 (1986), Byull Inst. Theor. Astron., 15, N 10, 583-586 ; R. Zh. 4.51.65 (1987), "Kinematika Fiz. Nebesn. Tel", 3, N 3, 94-96). In the paper by S.V. Tolbin observations of seven satellites of Saturn made in 1975 with 26" refractor of the Pulkovo observatory (40.100.006) are compared with the ephemerides based on above results by Yu. V. Batrakov and T.K. Nikol'skaya. Standard deviation of the position of a satellite relative to the planet is close to 0"2. In the series of papers by L.E. Bykova, V.V. Shikhalev and V.A. Yurga the work on construction of numerical theory of Phoebe is accomplished. Collection of processed observations of Phoebe at the time span from 1898 to 1981 is published, the orbit of Phoebe is refind using the modern observations form 1940 to 1976 (å=1"0) and the influence of various perturbations, including relativistic effects, on the motion of distant satellites of Jupiter and Saturn is investigated (39.100.023, 40.100.009, 41.099.005). In this "ThŠse de Doctorat" (1987, Universit‚ de Bordeaux, France) Dourneau presents observations made from 1980 to 1985 at Bordeaux, Pic du Midi, ESO and CFH and analyses them in order to build ephemerides by fitting previous theories from Kozai, Rapaport (S I - S II), Taylor (S VII) and Sinclair (S VIII). Taylor, in a paper published in 1984 (Astron. Astrophys. 141, 151, 38.100.068) made a comparison of the theory of the motion of Hyperion with observations made during 1967-1982. In the paper by Sinclair and Taylor in 1985 (Astron. Astrophys. 147, 241. The orbits of Titan, Hyperion, and Iapetus have been generated by both numerical integration and analytical theories and fitted to astrometric observations made in the period 1967-1982. c) - Satellite of Pluto In the paper by Tholen (1985) in Astron. J. 90, 2353 (40.101.043) an orbit of Pluto's satellite is fitted an 19 speckle inferferometric observations and on the observation of a partial occultation of the satellite by Pluto. III - THEORICAL STUDIES OF SATELLITE MOTIONS. a) - Galilean satellites In the paper by Henrard (1984) in Celestial Mech. 34, 255, 39.099.033, a new way of applying Hamiltoniam perturbation methods is presented in such a way that the theory is valid for large librations. Thuillot (1984) in Celest. Mech. 34, 245, 39.099.032, gives a method for obtaining developments of the secular elements related to the pericenters and the modes of the Galilean Satellites orbits with respect to variations of the dynamical parameters. Vu (1986) in his "ThŠse de doctorat" (Observatoire de Paris, France) developped an analytical study of the motion of the Galilean Satellites. The paper by Henrard and LemaŒtre (1987) in Icarus 69, 266 gives a perturbative treatment of the 2/1 jovian resonance. A study of the evolutionary paths in deep resonance (ie where mean motions taken by pairs an in ratios very close to 2/1) is made by greenberg in a paper published in Icarus 70, 334 (1987). In the paper by Campbell and Symmot Astron. J. 90, 364, 1985 , 39.099.017, data from Pioneer and Voyager are given about the gravity field of the jovian system. In two papers (1986), Io's acceleration is studied by Goldstein and Saroles in Astron. J., 92, 199, (42.099.050) and by Greenberg, Goldstein and Jacobs in Nature, 323, 789, (42.099.052). b.) Outer satellites of Jupiter. In the paper by T.S. Boronenko and Yu. B. Shmidt a literal solution of the satellite case of the restricted three-body problem is obtained by means of averaging Lie transformations with accuracy up to the eleventh order with respect to small parameter which is the ratio of mean mptions of the Sun and satellite. The results of application of the found series to the construction or analytical theories of JVI, JVII and JX are given ("Astron. i Geodez.", Tomsk, 1985, vyp. 13, 31-36 ; R.Zh. 3.51.68 (1987). The paper by T. V. Bordovitsyna, T.S. Boronenko, L.E. Bykova and A.M. Chernitsov (41.099.002) sums up the results of long years work of the authors on development of numerical and analytical theories of the outer satellites of Jupiter. The methods used in the work and main results are described. c.) - Satellites of Saturn In "Resonance in the motion of Planets, Satellites and Ast‚ro‹ds", Ferraz-Mello and Sessub eds, Univ. of Sao Paulo (1985), a paper by Salgado and Sessin studies the 2/1 commensurability in the Enceladus/Dione system (40.042.099) and one by Sato and Ferraz-Mello studies tthe 2/1 resonance in the same system (40.042.100). In the paper by I. G. Chugunov (41.100.055) the root-meansquare error of representation of observations by the theory developed early by the author are given for the Saturn's satellites II - VI. The author came to a conclusion about possibility of extensive application of the new theory. In the series of papers by I.G. Chugunov, G.V. Stolyarov and V.V. Stolyarov the qualitative investigation of the solution of the mathematical models describing resonant motions of some Saturn's satellites, as well as satellites in the other systems are given (38.100.076, 38.100.078, 39.100.020, 40.091.008, 40.091.017, 40.100.005, 41.099.045, "Differenz. uravneniya u prikl. zadachi, Tula, 1986, 8-9 ; R.Zh.11.51.60 (1986), "Astron. i Geodez., Tomsk, 1986, N 14, 103-107 ; r.zh. 4.51.55 (1987)). In the paper by Taylor, Sinclair and Message (Astron. Astrophys. in press) a spectral analysis has been made of the residuals obtained from fitting Woltjer's theory of Hyperion to the numerical integration of Sinclair and Taylor (1985) extended to ñ 25 years from epoch. d) Satellites of Uranus. The Laplacian resonance amongst uranian inner satellites is studied by Lazzaro, Ferraz Mello and Veillet in Astron. Astrophys., 140, 33 (1984), (38.101.18). A new determination of Miranda's orbital parameters from Laplacian resonance analysis is given by Lazzaro, Veillet and Viera Martins in "Resonance in the motion of Planets, Satellites and Astero‹ds", Ferraz-Mello and Sessin eds, Univ. of Sao Paulo, p. 85, (1985), (40.101.062). A period analysis of Laplacian resonance amongst Uranian inner satellites is given by Lazzaro and Viera Martins in Revista Mexicana Astronomia e Astrofisica, 12, 430 (1986), 41.101.062. In the paper by Laskar in 1986 (Astron. Astrophys. 166, 349) a general theory for the five main satellites of Uranus including the secular and short period terms is given ; this theory was compared by himself and Jacobson to the existing earth-based observations (in press). e) Miscellaneores The paper of resonant planetary perturbations on the evolution of the orbit of a satellite driven by tidal forces is studied in a paper by Kovalevsky (Celestial Mech., 34, 243, 1984). The existence of possible satellites of Mercury and Venus is examined by Rawal in Earth, Monn and Planets, 36, 135 (1986). IV - EPHEMERIDES. A review of satellite orbits and ephemerides is made by Ferraz-Mello in Celest. Mech., 34, 223 (1984),(39.097.005). A new compact representation of ephemerides is presented by Chapront and Vu (1984) in Astron. Astrophys., 141, 131 and ephemerides of the main satellites of Jupiter, Saturn and Uranus are given using the former representation by Arlot, Chapront, Ruatti and Vu in Astron. Astrophys. Supp. Series, 65, 383 (1986). V - FAINT SATELLITES. Orbital parameter estimates and associated incertainties of the small inner satellites of Jupiter determined from Voyager imaging data are presented in the paper by Synnot in 1984 (Icarus, 58, 178). Aksnes (Stab. of the Solar Syst. and its Minor Natural and Artificial Bodies, Ed. V.G. Schebehely, D. Reidel Pub. Co 1985, p.3) has reviewed the orbital status of the very faint Jovian and Saturnian satellites and their interactions with the planetary rings, in light of discoveries made with the Voyager spacecraft and from the ground (40.099.37). In the paper by Carusi, Roy and Valsecchi (Astron. Astrophys., 162, 312, 1986 (42.100.001)) the stability of the Saturnian satellite system is analyzed. Using imaging data, Synnot, in a paper in Icarus, 67, 189 (1986), shows the evidence of small satellites of Saturn in addition to those whose orbits had been firmly established by the time of the Voyager 2 encounter with Saturn. In the paper I.I. Agafonova and Eh. M. Drobyshevskij the origin of the irregular satellites of the planets as a result of explosions of the massive envelopes of the Galilean satellites is discussed (40.099.019). Burns, in 1986 (in "Satellites", Burns and Matthews eds, Univ. of Arizona Press, p.117) analyse the evolution of satellites orbits. In the paper by Sinclair (Astron. Astrophys., 136, 161, 1984, 38.100.002) the effects of orbital resonances on satellites in tadpole or horseshoe orbits relative to Mimas, Enceladus, Tethys or Dione are examined. The orbital resonances among Saturn's satellites (classical and newly discovered) are reviewed in "Saturn" p.593 (1984), (38.100.143) by Greenberg. In the paper by Lissauer, Goldreich and Tremaine (Icarus, 64, 425, 1985, 41.100.009), the evolution of Janus-Epimetheus coorbital resonances due to torques from Saturn's rings is studied. VI - RINGS. In her paper in Celestial Mech., 34, 297 (1984) (39.100.018), Borderies recalls the observations concerning the opaque rings of Saturn and Uranus and describe a model which represents the Kinematics of these rings. Brahic, in Adv. Space Res., 5, 121 (1985) (40.100.003), describes the dynamical processes of Saturn's rings. In Planetary Rings (Greenberg and Brahie editors, University of Arizona Press, 1984) observations, theories and problems related to the rings are reviewed. A series of paper concerns the Neptune arcs : discovery (Hubbard in Science, 231, 1276, (1986), (41.101.021) ; Hubbard and