Report of the working group on satellites for the Period July 1996 - June 1999 (J.E. Arlot) 1. Astrometric observations 1.1 Observations of the satellites of Mars Tentative observations were made at Pic du Midi Observatory without success because of the distance of Mars from the Earth. 1.2 Observations of the galilean satellites of Jupiter 1.2.1 Direct observations of positions Nikolaev Observatory (Ukraine). During the period from July 1996 to Dec 1998, 189 photographic positions of the galilean satellites of Jupiter were obtained with the zonal astrograph (D=120 mm, F=2044mm). In the year 1997 the observations were made during the period of the mutual events and in the year 1998 during the close approach of the satellite system with the star N 117881 from the HIPPARCOS catalogue. The observations of 1996 were processed using PPM catalogue and the observations of 1997, 1998 in the ICRS using HIPPARCOS and ACTRC star catalogues. The results are not published as yet, but are available by application to the authors. The results of observations made since 1962 up to 1996 with the zonal astrograph were twice reprocessed. As result two catalogues of 1314 improved satellite positions were obtained: the catalog in the system FK5 (with PPM star catalog) and other one in the system ICRS (with HIPPARCOS and ACTRC star catalogues). These results are in preparation for publication. During the period from 1996 to 1998, 69 positions of the galilean satellites were determined by photoelectric meridian observations with Repsold meridian circle equipped by CCD-microscopes (F=2150 mm, D=150 mm, D of circle = 1200 mm). Pulkovo Observatory (Sankt-Petersburg, Russia) The astrometric observations of the Galilean satellites with 26-inch refractor in 1996-1999 have been completed. The photographic plates NP-27 and CCD-kamera ST-6 were used. The 5 plates were taken with 5 or 6 exposures on every plate. More than 1000 CCD exposures were made for the Galilean satellites and 5 sets of exposures to determine apparent distances between satellites. One pass of the satellite Europa near the star of HIPPARCOS catalogue was observed with the CCD-kamera. Institute of Applied Astronomy (Sankt-Petersburg, Russia) In the Observatory Teide (Instituto de Astrofisica de Canarias, Spain) in collaboration with Institute of Applied Astronomy (Sankt-Petersburg, Russia) the astrometric CCD observations of Galilean satellites relatively to HIPPARCOS star 104297 in the time of the close conjunctions at Nov 12-14 1997 were made in the observatory Teide. The normal places in the form of absolute positions of the satellite with the accuracy better than 20 mas were derived as well as a normal place for the position of Jupiter with the accuracy 10 mas. Regular observations of natural satellites of in the times of close conjunctions with HIPPARCOS stars (when the direct CCD observations might be produced) in the observatory Teide with the telescope IAC-80 (D= 82 cm, F=900 cm) were initiated. Until now the series of such observations were made for Galilean satellites in Oct 26 - Oct 28, 1998 and 896 pairs of coordinates were obtained. U.S.Naval Observatory (Washington, D.C., USA) Photographic observations of the Galilean satellites of Jupiter, (and satellites I-VIII of Saturn) were continued by D. Pascu with the 26-inch refractor at Washington through 1998. Observations will resume when a suitable substitute for the discontinued Kodak 103aG plate is found. The automatic plate measuring machine is being refurbished and is expected to be operational by the end of 1999. At that time it is expected to remeasure the entire plate archive for the purposes of high precision plate reductions using Hipparcos and Tycho stars. Such reductions would give precise positions for the planet as well as the satellites. 1.2.2 Photometric observations of occultations and eclipses Phemu97 campaign of observations organized by Institut de mecanique celeste-Bureau des longitudes provided more than 400 light curves of mutual events of the galilean satellites of Jupiter. In France observations were conducted in Meudon, Pic du Midi, Grasse, Bordeaux and Haute-Provence observatories leading to 89 light curves as follow: Observatory Telescope Aperture Receptor Nb of observations Observatoire de Haute Provence reflector 80cm CCD 9 Observatoire du Pic du Midi reflector 102cm CCD 12 Observatoire photoelectric de Paris refractor 38cm photometer 5 Observatoire de Meudon reflector 100cm TV CCD camera 7 Observatoire de Bordeaux reflector 60cm CCD 22 Observaoire multichannel B,V,R de Grasse (Calern) reflector 100cm photoelectric 3x10 photometer. Observations were made at the M.G. Fracastoro Station of Catania Astrophysical Observatory. Using the photon counting photometer of the 91-cm Cassegrain telescope more than 80 phenomena were observed, 28 of which are suitable to provide elements useful to determine accurate astrometric positions of interest for the dynamical studies of galilean satellites. The lightcurve data of these events were sent to the Institut de mecanique celeste - Bureau des Longitudes to be published in the Phemu97 catalogue. A campaign of photometric observation of the Galilean satellites of Jupiter during their mutual occultations and eclipses in 1997 on the observatories of Kazakh republic, Russia and Ukraine were organized by Sternberg Astronomical Institute (SAI) Moscow, Russia. A treatment of the photometric results was made and the mutual planetocentric positions of satellites were derived in SAI by N.Emelianov. As the main result 44 light curves were obtained for 31 mutual evens of the Galilean satellites. Distribution of the obtained light curves among the observatories is following: Observatory Telescope Aperture Focal length Receptor Nb of obs. Fesenkov Astrophys. Institute, Alma-Ata Zeiss-600 60 cm 12381 mm CCD ST-6 13 Republic Kazakhstan Voronezh Refractor 60 cm 3000 mm 2 State University Reflector 100 cm 8000 mm visual Russia Astronomical Station of the Odessa Reflector 80 cm 11000 mm photometer 2 State University Dushak-Erekdag Ukraine Main Astronomical Observatory AZT-2 70 cm 10500 mm TV photometer 3 of the Ukrainian Academy of Science Kiev, Ukraine Kourovka observatory of Ural state AZT-3 45 cm 10000 mm photometer 8 university, Ekaterinburg, Russia Observatory of the Crimean laboratory Zeiss-600 60 cm 7500 mm photometer 12 of the Sternberg Refractor 40 cm 1600 mm CCD ST-8 Astronomical Institute, Moscow, Russia Main Astronomical Observatory of the Refractor 60 cm 10400 mm CCD ST-6 4 Russian Academy of Sciences, Pulkovo, S.-Petersburg, Russia A large number of observatories participated also to the campaign of observation of the mutual events such as: Palomar-USA (J. Goguen), Mauna Kea-Hawai (D. Tholen), Topeka-USA (HART), Vainu-India (R. Vasundhara), Boskoop (H.J. Bulder), Torino-Italy (P. Tanga), Teide (R. Casas), Lowell (J. Spencer), Bucarest-Romania (G. Vass), Wellesley-USA (French), Okayama-Japan (Okura), ... K. Aksnes et al. (BAAS 30, 1147, 1998) and A.A. Kaas et al. (Astr. J. 117, 1933, 1999) have derived astrometric data for the Galilean satellites from 213 light curves of 86 mutual events that occurred in 1990-1992. The data were drawn mainly from the PHEMU91 data set provided on the Web by IMC-Bureau des Longitudes. These results and those from extensive data sets of mutual events in 1985 were compared with the E3 and E5 ephemerides developed by J. Lieske. 1.3 Observations of the faint satellites of Jupiter Goloseevo observatory (Kiev, Ukraine) In September 1998 the CCD observations of the JXIV and JV satellites were made with the 2-meter telescope and Two-Channel Focal Reducer in the observatory Terskol (North Caucasus) in collaboration with Max-Plank-Institut fur Aeronomie, Katlenburg-Lindau, Germany. After processing of these observations 29 positions of Thebe and 8 positions of Amalthea are obtained relative to the Galilean satellites of Jupiter. Haute-Provence Observatory/Institut de mecanique celeste-BDL (France) In August and December, 1998, CCD observations provided 43 absolute positions of JVI, 23 of JVII, 53 of JVIII, 35 of JIX, 29 of JX, 27 of JXI, 18 of JXII and 16 of JXIII. U.S. Naval Observatory (Washington D.C., USA) CCD observations were made for JV and JXIV by Pascu and Rohde with the 61-inch Astromeric Reflector at Flagstaff. These observations provide both astrometric and photometric data, and have been used by USNO, JPL and BDL for ephemeris developement (Wells, E., Flynn, B., Gradie, J., Johnson, R., Pascu, D., Stern, A., Thomas, P., Zellner, B.: 1996, "Spectrophotometry of Amalthea and Thebe", Bull. Amer. Astron. Soc., 28, 1071). 1.4 Observations of the satellites of Saturn 1.4.1 Direct observations of positions Nikolaev Observatory (Ukraine) During the period from July 1996 to Dec 1998, 26 photographic positions of the satellites of Saturn were obtained with the zonal astrograph (D=120 mm, F=2044mm) and 8 positions of Titan were determined with Repsold meridian circle. Pulkovo Observatory (Sankt-Petersburg, Russia) The major Saturn's satellites were observed with 26-inch refractor. 33 photographic plates were taken with 5 or 6 exposures on every plate during the period from July 1996 to June 1999. With the CCD camera installed at 26-inch refractor 100 sets of images by 5 to 60 exposures on each of them. From these observations 44 mutual apparent distances were obtained. The internal errors of mutual distances are of 0.04 arcsec. After the processing of the photographic observations of the period from 1994 to 1998, 244 mutual positions of the major Saturn's satellites were obtained as well as 205 positions relative to the planet. The internal precision of these observations fall to be of 0.12 arcsec. Goloseevo observatory (Kiev, Ukraine) In September 1998 the CCD observations of the SII-SVII and SIX satellites were made with the 2-meter telescope and Two-Channel Focal Reducer in the observatory Terskol (North Caucasus) in collaboration with the Max-Planck-Institut fuer Aeronomie, Katlenburg-Lindau, Germany. After processing a part of these observations 10 positions of Phoebe are obtained relative to the stars of USNOA-2.0 catalog with the internal precision of 0.35 arcsec. A series of photographic observations made in 1961-1984 is currently being processed and so far 360 positions of the satellites SIII-SVI and SVIII have been obtained relative to the stars of PPM and ACT catalogues with the internal precision of 0.18 - 0.22 arcsec. Bordeaux Observatory Observations are made with a CCD meridian circle. A first 512x512 pixel CCD camera was mounted in 1994, and second larger camera(1024x1024) in 1996. This camera works in scan mode, with a declination field of 28' . The mean internal precision of a single observation is about 0.05 arcsec in both coordinates for magnitudes 9 < V <14 . Rhea, Titan, Hyperion, Iapetus are observed; the astrometric positions obtained are compared to the ephemerides built from the theories of D. Harper, D. Taylor and of A. Vienne, L. Duriez . La Palma Observatory CCD observations of the eight major satellites of Saturn were taken on La Palma using the Jacobus Kapteyn Telescope in 1990-1994(D.Harper, C.D.Murray, K.Beurle, I.P.Williams, D.H.P.Jones, D.B.Taylor and S.C.Greaves Astron.Astrophys.Suppl.Ser.121,65-69(1997)) and in 1995 and 1997(D.Harper, K.Beurle, I.P.Williams, C.D.Murray, D.B.Taylor, A.Fitzsimmons and I.M.Cartwight Astron.Astrophys.Suppl.Ser. 136,257-259(1999)). Brasopolis Observatory (using the 1.6 m Ritchey-Chretien Reflector or the 0.6m for a few observations) Astrometric positions of the first eight Saturnian satellites obtained from 138 photographic plates taken in 30 nights in the years 1982 to 1988 are reduced. All positions are compared with those calculated by the theory TASS1.7. The observed minus calculated residuals give rise to standard deviatios smaller than 0".3. These positions are presented in the paper: Veiga C.H., Vieira Martins R.: "Photographic positions for the first eight satellites of Saturn", Astron. Astrophys. Suppl. (submitted) (1999). For Phoebe, 60 CCD frames taken in 10 nights are reduced. The observations were distributed between 5 missions in the years 1995 to 1997. For the astrometric calibration the USNO-A2.0 Catalogue was used. All positions were compared with Jacobson calculations. The residuals had standard deviation smaller than 0".5. These results are presented in the paper: Veiga C.H., Vieira Martins R., Andrei A.H.: "Astrometric positions of Phoebe", Astron. Astrophys. Suppl. (submitted) (1999). Haute-Provence Observatory/Institut de mecanique celeste-BDL (France): A series of 102 observations of the major satellites of Saturn was made in December 1998; 135 CCD images of Phoebe were obtained in August and December, 1998. A paper will be published in Astron. Astrophys. U.S.Naval Observatory (Washington, D.C., USA) Photographic observations of satellites I-VIII of Saturn were continued by D. Pascu together with the galilean satellites observations (cf. 1.2.1). In addition to the photographic program for the bright moons and planet, CCD observations were made for SXII, SXIII, SXIV, by Pascu and Rohde with the 61-inch Astromeric Reflector at Flagstaff. These observations provide both astrometric and photometric data, and have been used by USNO, JPL and BDL for ephemeris developement. 1.5 Observations of the satellites of Uranus Bordeaux Observatory: The satellites of Uranus Ariel, Umbriel, Titania, Oberon are also observed . For these satellites,astrometric positions of the central planet are also obtained . Brasopolis Observatory (using the 1.6 m Ritchey-Chretien Reflector or the 0.6m for a few observations) Astrometric positions of the five largest Uranian satellites (Miranda, Ariel, Umbriel, Titania and Oberon) from 750 CCD frames carried out during 35 nights distributed in 12 missions in the 1995-1998 period are presented in the paper: Veiga C.H., Vieira Martins R.: "CCD astrometric observations of Uranian satellites", Astron. Astrophys. Suppl. (in press) (1999). Observed positions are compared with calculated positions from GUST86. The standard deviations are better than 0".05 for the four largest satellites and 0".08 for Miranda. Goloseevo observatory (Kiev, Ukraine) The results of photographic observations made in 1990 with the reflector (D=600mm,f=7400mm) in Majdanak were processed with the HIPPARCOS catalog thus 60 positions of the major satellites of Uranus were obtained. U.S.Naval Observatory (Washington, D.C., USA) CCD observations were made for UV by Pascu and Rohde with the 61-inch Astromeric Reflector at Flagstaff. These observations provide both astrometric and photometric data, and have been used by USNO, JPL and BDL for ephemeris developement. D. Pascu and colleagues applied the Planetary Camera of the Hubble Space Telescope (HST)to observe the faint inner satellites of Uranus. The results for the eight brightest of the inner moons of Uranus were published in 1998. Mean motion corrections were determined for these eight moons, and an astrometric precision of 9 mas was achieved for 20th V magnitude Puck (Pascu, D., Rohde, J.R., Seidelmann, P.K., Wells, E., Kowal, C., Zellner, B., Storrs, A., Currie, D.G., and Dowling, D.M., 1996, "Astrometry and Orbits of the Inner Uranian Satellites," Bull. Amer. Astron. Soc., 28, 1184; Storrs, A.D., Zellner, B., Wells, E.N., Buratti, B., Currie, D., Seidelmann, K., Pascu, D., 1996, "Spectrophotometry of Small Uranian Satellites", Bull. Amer. Astron. Soc., 28, 1072; Pascu, D., Rohde, J.R., Seidelmann, P.K., Wells, E., Kowal, C., Zellner, B., Storrs, A., Currie, D.G., and Dowling, D.M., 1998, "HST Atrometric Observations and Orbital Mean Motion Corrections for the Inner Uranian Satellites," Astronom. J. 115, 1190). 1.6 Observations of the satellites of Neptune Bordeaux Observatory: Triton, satellite of Neptune is also observed together with the positions of Neptune. Brasopolis Observatory (using the 1.6 m Ritchey-Chretien Reflector or the 0.6m for a few observations) Photographic positions of the Neptunian satellites Triton (53 positions taken in 1985, 1987 and 1988) and Nereid (8 positions taken in 1982, 1984 and 1985). All positions were compared with those calculated from Harris for Triton and from a numerical integration for Nereid. The observed minus calculated residuals referred to Neptune have standard deviations of the order of 0".05 for Triton and 0".25 for Nereid. These positions were presented in the paper: Veiga C.H., Vieira Martins R., Le Guyader Cl., Assafin M.: "Positions of Neptunian Satellites", Astron. Astrophys. Suppl. Series 115, 319-324 (1996). CCD astrometric positions of Triton are given for the oppositions of Neptune for 1989 to 1997. In the period from 1989 to 1994, 433 positions distributed in 29 nights were obtained. When compared with calculated positions from Jacobson et al., the observed minus calculated residuals referred to Neptune have standard deviation of the order of 0".11. These results are presented in the paper: Veiga C.H., Vieira Martins R.: "CCD observations of Triton", Astron. Astrophys. Suppl. Series 120, 107-109 (1996). In the period from 1995 to 1997, 759 positions were obtained during 35 nights. The standard deviation of the residuals were about 0".09. These results were presented in the paper: Veiga C.H., Vieira Martins R.: "New CCD positions of Triton and comparison with the theory", Astron. Astrophys. Suppl. Series 131, 291-293 (1998). 229 CCD positions of Nereid were taken in 23 nights between 1993 and 1998. Using a numerical integration method it was fitted an orbit over all the published observations of this satellite in order to determine one state vector of this orbit. This state vector which is near one calculated by Jacobson gave a standard deviation equal 0".16 for the 229 observations. These results were presented in the paper: Veiga C.H., Vieira Martins R., Le Guyader Cl.: "CCD observations of Nereid and a new orbital determination", Astron. Astrophys. Suppl. Series 136, 445-451 (1999). Institute of Applied Astronomy (Sankt-Petersburg, Russia) In collaboration with the observatory Teide (Instituto de Astrofisica de Canarias, Spain) the series of the CCD observations of Triton in the times of close conjunctions with HIPPARCOS stars with the telescope IAC-80 (D= 82 cm, F=900 cm) were made in Apr 30 - May 8, 1999 and 317 pairs coordinates were obtained. Goloseevo observatory (Kiev, Ukraine) The results of photographic observations made in 1987 with the reflector (D=600 mm, F=7400 mm) in Majdanak were processed with the HIPPARCOS catalogue and 4 positions of the Triton were obtained. U.S. Naval Observatory (Washington, D.C., USA) D. Pascu and colleagues applied the Planetary Camera of the Hubble Space Telescope (HST)to observe the faint inner satellites of Neptune. Observations were obtained in 1997. While these observations are difficult to calibrate, preliminary reductions indicate a somewhat greater precision (Pascu, D., Rohde, J.R., Seidelmann, P.K., Wells, E.N., Hershey, J.L., Zellner, B.H., Storrs, A.D., Currie, D.G., Bosh, A.S., 1998, "HST Observations of the Inner Satellites of Neptune," Bull. Amer. Astron. Soc. 30, 1144; Pascu, D., Rohde, J.R., Seidelmann, P.K., Wells, E.N., Hershey, J.L., Zellner, B.H., Storrs, A.D., Currie, D.G., Bosh, A.S., 1998, "HST BVI Photometry of Triton and Proteus," Bull. Amer. Astron. Soc. 30, 1101. 1.7 Miscellaneous The data base NSDC of astrometric positions of planetary satellites has now a bibliographic database linking the observations to the paper documenting the observations. The data base received new observations which were added on the ftp server. All observations are not yet reachable through the interactive software NSDB. Some observational and reduction methods used for work on natural satellites are presented in the papers: Vieira Martins R., Veiga C.H., Assafin M.: "Astrometric Observations of Faint Satellites", in S. Ferraz Mello, B. Morando and J-E. Arlot eds: "Dynamics, Ephemerides and Astrometry of the Solar System" (Proceedings of the IAU Symposium 172), Kluwer Academic Press, 419-422 (1996). Veiga C.H., Vieira Martins R.: "A method to reduce positions of natural satellites based on observations made at Laboratório Nacional de Astrofísica/CNPq/MCT-Itajubá-Brasil", (PHESAT95 Workshop on the observation of the phenomena of the satellites of Saturn in 1995. J-E. Arlot and M. Stavinschi, editors) Annales de Physique, Colloque 21, Supplément au no1, vol. 21, 163-167 (1996). Vieira Martins R., Veiga C.H.: "Natural Satellites", "Proceedings of the XXth Annual Meeting of the Sociedade Astronômica Brasileira (august 1994)", 11-19, Brazil (1996). Review papers on the CCD long focus observations were published such as: Pascu, D. (1996), "CCD Observations of Planetary Satellites at the U.S. Naval Observatory," Annales. de Physique, Coll. C1, supp. 1, eds. J.-E. Arlot and M. Stavinschi, 21, C1-109-115. Pascu, D. (1996), "Long-focus CCD astrometry of planetary satellites", in Dynamics, Ephemerides and Astrometry of the Solar System, eds. S. Ferraz-Mello, B. Morando and J.-E. Arlot, Proceedings of IAU Symposium 172, Kluwer Academic Publishers: Dordrecht. Pascu, D., Rohde, J.R., Seidelmann, P.K., Wells, E., Kowal, C., Zellner, B., Storrs, A., Currie, D.G., and Dowling, D.M. (1997). "Astrometry of Faint Planetary Satellites with WFPC2 of Hubble Space Telescope," in Dynamics and Astrometry of Natural and Artificial Celestial Bodies. Proceedings of IAU Coll. 165, eds. I.M. Wytrzyszczak, J.H. Lieske and R.A. Feldman, p. 517. Papers on the impact of Hipparcos catalogue on planetary satellites observations were published: Pascu, D., Fienga, A. and Arlot, J.-E., 1997, "Archival High-Precision Astrometric Observations of Jupiter," Bull. Amer. Astronom. Soc. 29, 1103; Fienga, A., Arlot, J.-E. and Pascu, D., 1997, "Impact of Hipparcos data on astrometric reduction of solar system bodies," in Proceedings of the ESA Symposium,"Hipparcos - Venice '97," ESA SP-402, p. 157. 2. Theoretical works and comparisons to Observations 2.1 Satellites of Mars Jet Propulsion Laboratory (USA) R.A Jacobson from JPL reports: The verification of the current JPL Phobos ephemeris with imaging observations from the Mars Global Surveyor spacecraft in 1998. The observations indicated that no ephemeris update was needed. 2.2 Galilean satellites of Jupiter Jet Propulsion Laboratory (USA) R.A Jacobson from JPL reports: -a determination of the orbits (precessing ellipses) of the four inner satellites from the original Voyager imaging observations, astrometric observations through 1997, and the Galileo imaging observations (Jacobson 1997: Bull. AAS 29, No.4, 1098). This work is scheduled to be completed and published later this year. -a fit of numerically integrated Galilean satellite orbits to astrometric observations (1967 to 1996), Voyager imaging observations, mutual events (1973, 1979, 1985, 1991), eclipses (1967 to 1996), and Galileo data (1995 to 1999). This is an ongoing project, see Jacobson (1998: Bull. AAS 30, No.3, 1147) for an interim report. H.M. Nautical Almanac Office (Rutherford Appleton Laboratory, U.K.) D.B. Taylor reports that Hipparcos observations of Europa(J2) and Titan(S6) and Tycho observations of Ganymede(J3) and Callisto(J4) are analysed to give checks on the latest Jet Propulsion Laboratory ephemerides of the planets Jupiter and Saturn(L.V.Morrison, D.Hestroffer, D.B.Taylor and F.van Leeuwen Proceedings of the ESA Symposium `Hipparcos-Venice '97`, 13-16 May, Venice, Italy, ESA SP-402 (July 1997)). Sternberg Astronomical Institute (Moscow, Russia) A method for treatment of the photometric observations of the natural satellites during their mutual occultation and eclipses was elaborated by N.Emelianov. This method consists in computing of mutual planetocentric rectangular coordinates of satellites for one moment from each observed light curve. The precision estimation is made while the treatment. The light curves of mutual events of Galilean satellites of Jupiter in 1997 were treated with this method and 44 mutual planetocentric rectangular coordinates of satellites were deduced. The result are to be published. Institute of Applied Astronomy (Sankt-Petersburg, Russia) From the preliminary analysis of the results of astrometric observations of Galilean satellites (1962-1997) which were made and re-reduced in Nikolaev Observatory (Ukraine) it was shown that the reduction greatly improved the accuracy of the observations (the error of single observation is 0.12-0.15 arcs) and this series appears to be quite informative for astrometry, particularly for improving ephemerides of Jupiter. The corrections to elements of Jupiter in DE403 ephemeris were obtained. these results were confirmed by analysis of observations made be Carlsberg meridian circle. Photometric light curves obtained in the observational campaigns PHEMU85 and PHEMU91 were processed. Astrometrical data in the form of moments of contacts of apparent disks (or apparent disks with umbra and semi-umbra for eclipses) as well as moments of maximums of the light curved were derived. A numerical model for Galilean satellites was developed and compared with Lieske's theory on the time span 1962-1997. Model provides as rectangular coordinates of the satellite so partials with respect to initial state vector, masses of Jupiter and satellites, and coefficients of gravitational harmonics. Institut de mecanique celeste-Bureau des longitudes (France) The series of observations made by D. Pascu at USNO were re-reduced using the Hipparcos catalogue. Absolute R.A. and declination of the galilean satellites were obtained and positions of Jupiter were deduced in order to correct the elements of the orbits of the planet itself.(Fienga A. , Arlot J.E. and Pascu D., Proceedings of the ESA Symposium `Hipparcos-Venice '97`, 13-16 May, Venice, Italy, ESA SP-402 (July 1997)) 2.3 Satellites of Saturn Jet Propulsion Laboratory (USA) R.A Jacobson from JPL reports: A fit of a numerically integrated Phoebe orbit to astrometric (1904 to 1996) and the Voyager 2 imaging observations (Jacobson 1998: Astronomy & Astrophysics Supplement Series 128, pp. 7). H.M. Nautical Almanac Office (Rutherford Appleton Laboratory, U.K.) D.B. Taylor reports the analysis of the satellite Titan (cf. above). 2.4 Satellites of Uranus Jet Propulsion Laboratory (USA) R.A Jacobson from JPL reports: -a redetermination of the minor satellite orbits from the original Voyager imaging observations and 1994 HST observations (Jacobson 1998: Astronomical Journal 115, pp. 1195). -a fit of numerically integrated orbits for the newly discovered Uranian satellites, Caliban and Sycorax, to observations (pre-discovery to 1998) (Jacobson 1999: Meeting of the American Astronomical Society Division on Dynamical Astronomy, Estes Park, Colorado). H.M. Nautical Almanac Office (Rutherford Appleton Laboratory, U.K.) D.B.Taylor(Astron.Astrophys.330,362-374(1998)) compiled a catalogue of all available published and unpublished Earth-based observations of the 5 major satellites of Uranus. A numerical integration was fitted to observations(Earth-based and Voyager astrographic data) in the time interval April 1977 to October 1995. The physical parameters of the system were determined. The masses of the 4 outer satellites are found to be sensitive to the weights used for the spacecraft data. Details of the determination of the starting conditions for the ephemerides of the 5 major satellites is given in NAO Technical Note No.72(1998). Included in this numerical integration were the observations taken with the Jacobus Kapteyn Telescope on La Palma in 1990 and 1991 (D.H.P.Jones, D.B.Taylor and I.P.Williams Astron.Astrophys.Suppl.Ser.130,77-80(1998)). Institute of Applied Mathematics (Moscow, Russia) On the base of orbital data about the two new uranian satellites S/1997 U1 (Caliban) i S/1997 U2 (Sicorax) the orbit evolutions have been studied by M. Vashkoviak. The limits of eccentricities and inclinations as well as the periods of pericentres and nodes revolutions have been obtained. This analysis were accomplished with a general solution of the twice averaged Hill problem. Minor Planet Center Orbit calculations have been performed in 1998 for the Uranian satellites S/1997 U1 and S/1997 U2 by B.G. Marsden, G. Williams, and K. Aksnes (IAU Circ. 6834, 6869, 6870). 2.5 Miscellaneous R.A. Jacobson from JPL reports that he continued to improve the JPL's satellite observation processing software system, maintained and updated his observations database, and provided ephemerides to a number of JPL and non-JPL users (we have up to date ephemerides for all of the natural satellites except the newly discovered S/1986 U 10). Our ephemerides are available on line via the JPL Horizons system (Giorgini et al. 1996: Bull. AAS 28, No.3, 1158). He has also been supporting the Galileo Galilean satellite gravity science work (Anderson et al. 1998: Bull. AAS 30, No.2, 826, Science Vol. 280 pp. 1573-1576 and Science Vol. 281 pp. 2019-2022). 3. Rings and interplanetary dust D.P.Hamilton of Cornell Univ. in collaboration with A.V.Krivov (1996, Icarus, 123, 503-523) developed the analytical theory for the circumplanetary dust dynamics taking into account the planetary oblateness, radiation pressure, Lorentz force acting on a grain with a constant charge moving in the magnetic field of dipole and the solar gravity represented by the tidal term. The applications of this theory were the motion of grains in Martian dust belts along the orbits of Phobos and Deimos, Saturn's E ring, the motion of the outer Jovian satellite Elara and of its dusty ejecta. For the planar case they considered, they derive an integral of the motion. A.V.Krivov, L.L.Sokolov and V.V.Dikarev, (1996, Cel. Mech. Dynam. Astron., 63, 313-339) investigated the dynamics of Mars-orbiting dust. The equations of motion of particles governed by radiation pressure and Mars' oblateness in Lagrangian non-singular elements were deduced and solved, both analytically and numerically. It was stated that the coupled effect of both forces is essential so that on no account can the oblateness of Mars be neglected. A.V.Krivov and D.P.Hamilton (1997, Icarus, 128, 335-353) modeled the presumed dust belts of Mars having combined theoretical results described above with up-to-date impact models. They used a new numerical code to construct a three-dimentional, time-dependent, and size-dependent distribution of dust material. The normal and edge-on optical depths of the Phobos and Deimos tori were estimated to lie in the interval from 1E-8 to 1E-5. A.V.Krivov and A.Jurewicz of Space Research Centre (1999, PSS) studied the statistics, spatial distributions, and volume densities of the impact ejecta from Phobos and Deimos in the vicinities of these moons. Also explored were the time variations in the dust clouds caused by individual impacts of large meteorites. A.V.Krivov with H.Krueger and E.Gruen of Max-Planck-Institut fuer Kernphysik and K.-U.Thiessenhunsen of Potsdam Univ. suggested fast impact ejecta from the Galilean moons as a possible explanation of the origin of "big" grains detected by Galileo spececraft. V.V.Dikarev and A.V.Krivov (1998, Astronomicheskii Vestnik, 32(2), 147-163) investigated the dynamics of the particles of Saturn's E ring with allowances for perturbations caused by radiation pressure, planetary oblateness, the Lorentz force determined by three zonal harmonics of the planetary magnetic potential, and plasma drag. A collective model of the E ring was constructed. V.V.Dikarev (1999, A&A, 346) considered the motion of an E ring grain carrying variable charge and being subject to the plasma drag force as well as the radiation pressure and planetary oblateness. He extended the integral of the motion (Hamilton and Krivov 1996) for the case of variable charge and suggested an analytical description of the grain's motion accounting for the plasma drag. One of the findings was that not only is the constant charge able to develop large orbital eccentricity of the grains ejected from Saturn's satellite Enceladus but the variable charge is able as well providing the explanation for the E ring large radial extent. Plasma drag was argued to be important force influencing the grain dynamics and the ring's structure. M. Banaszkiewicz of Space Research Centre (Warsaw, Poland) and A.V.Krivov (1997, Icarus 129, 289-303) argued that Hyperion may act as a reasonably effective source of dust in the saturnian system. Eventually the dust ejected (e.g. due to hypervelocity impacts of interplanetary grains or dust particles coming from the outermost moon Phoebe) from Hyperion and subject to the perturbations due to Titan's gravity, solar radiation pressure and plasma drag force, can either collide with Titan, spread into the inner part of the saturnian system, or escape to the interplanetary space. It is suggested that the predicted influx of icy (H2O) particles from Hyperion, if large enough, could affect chemical processes in Titan's atmosphere and might provide an explanation for some of its observed features, such as an anomalous abundance of CO2 molecules.