Report on Satellites (J.E. Arlot) 1) Astrometric observations U.S. Naval Observatory CCD observations of Amalthea (JV), Thebe (JXIV), Helene (SXII), Telesto (SXIII), and Calypso (SXIV), and IR observations of Thebe (JXIV), Amalthea (JV), Metis (JXVI), Adrastea (JXV), Miranda (UV), and Triton (NI), were obtained with the 61-inch Astrometric Reflector at Flagstaff, during 1992-2000, and were reduced and sent to JPL for ephemeris development (Pascu, Rohde, Vrba, Martinka, Grefenstette, Ries). Observations of close approaches of pairs of the Galilean satellites of Jupiter were observed with the speckle camera and the 26-inch, in preparation for observing the "mutual phenomena" astrometrically in 2003. (Mason, Kaplan, Douglass, Pascu, Aksnes: 1999, BAAS, 31, 1225) Pulkovo observatory (Pulkovo, Russia) The results of photographic observations of the Saturnian satellites with 26-inch refractor at Pulkovo in 1994-1998 are published (Kisseleva T.P. and Kalinichenko O.A.: 2000, Izvestiia glavnoi astronomicheskoi observatorii Pulkovo, 214, 344-355). These results include 292 mutual positions of the satellites S2-S6 and S8. The results of determinations of relative positions of satellites of Saturn and Jupiter in five years period (1995-2000) with CCD and 26-inch refractor at Pulkovo observatory are published (Kisseleva T.P. and Izmailov I.S.:2000, Izvestiia glavnoi astronomicheskoi observatorii Pulkovo, 214, 333-343). The relative coordinates of 74 observations of pair of saturnian satellites and 8 ones of satellites of Jupiter are given in tables. In result of revision of observations of Saturnian satellites made in Abastumany Astrophysical observatory with Double Wide-field astrograph in 1984 four positions of Hyperion and 20 positions of S4, S5, S6, and S8 have been produced relative to ACT catalogue (Kisseleva T.P. and Chanturiya S.M.: 2000, Izvestiia glavnoi astronomicheskoi observatorii Pulkovo, 214, 356-360). Astrometric observations of Saturn's satellites Titan (4 positions), Hyperion (10 positions), Iapetus (11 positions), and Phoebe (5 positions) were made in Pulkovo Observatory with ZA-320 Mirror Astrograph in 1998-1999 and these results published (Devyatkin A.V., Gorshanov D.L., Gritsuk A.N., Svidunovich A.G.: 2000, Izvestiia glavnoi astronomicheskoi observatorii Pulkovo, 214, 382-386). Goloseevo observatory (Kiev, Ukraine) The CCD observations of the four close satellites of Jupiter were made with the 2-meter telescope and Two-Channel Focal Reducer in the observatory Terskol (North Caucasus) in 1998-2000. From these observations 64 positions of Amalthea, 84 positions of Thebe, 42 positions of Adrastea and 128 positions of Metis are published (Ledovskaya I.V., Jockers K., Karpov N.V., Sergeev A.V.: 1999, Kinematika i Fizika Nebesnykh Tel., 15, N.6, 483-488). Nikolaev observatory (Nikolaev, Ukraine) Observations of galilean satellites made in Nikolaev in 1962-1998 were processed using PPM catalog and the HIPPARCOS and ACTRC star catalogues. The 1314 absolute positions are published. Bordeaux observatory (France) They continued to observe the system of the bright satellites of Saturn with the transit circle instrument of Bordeaux observatory equipped with a CCD. Using TASS ephemerides, they deduced "observed" positions of Saturn. Positions of Hyperion and Iapetus were observed and compared with the theory made by Duriez and by Vienne. Observations of Titania and Uranus were made during spring and summer 2001 in order to prepare the observation of an occultation of an Hipparcos star by Titania. An offset in the ephemerides was deduced from these observations. Institut de mecanique celeste/Bureau des longitudes (observatoire de Paris, France) During the period 1999-2002, a campaign of observations of the outer satellites of Jupiter and Saturn was organized at the observatoire de Haute-Provence. 163 observations of J6, 165 of J7, 185 of J8, 165 of J9, 156 of J10, 156 of J11, 155 of J12, 166 of J13, 94 of J17 45 of S/2000S3 and 413 of S9 Phoebe were made (Fienga, A., Arlot, J-E., Baron, N., Bec-Borsenberger, A., Crochot, A., Emelyanov, N., Thuillot, W.: 2002, Astron. Astrophys. 391, 767). In addition, 160 positions of the Galilean satellites were observed and 99 of the bright satellites of Saturn. Nereid, the satellite of Neptune was also observed. The catalogue of the observations of mutual events of the satellites of Saturn made in 1995 was published (Thuillot, W., Arlot, J.-E., Ruatti, Ch. , Berthier, J., Blanco, C., Colas, F., Czech, W., Damani, M., D´Ambrosio, V., Descamps, P., Dourneau, G., Emelianov, N., Foglia, S., Helmer, G., Irsmambetova, T.R., James, N., Laques, P., Lecacheux, J., Le Campion, J.-F., Ledoux, C., Le Floch, J.-C., Oprescu, G., Rapaport, M., Riccioli, R., Starosta, B., Tejfel, V.G., Trunkovsky, E.M. Viateau, B., Veiga, C. H., Vu, D. T.: 2001, Astron. Astrophys. 371, 343). Observations of Puck, the satellite of Uranus, were made using adaptive optics at the European Southern Observatory (Descamps, P., Marchis, F., Berthier, J., Prangé, R., Fusco, Th., Le Guyader, Cl.: 2002, C.R.A.S. 3, 1, 121-128, Descamps, P., Marchis, F., Berthier, J., Prange, R., Leguyader, C.: 2000, BAAS, DPS meeting 32, 42.04). Inner satellites of Jupiter Amalthea and Thebe were observed at Pic du Midi observatory. Minor Planet Center Prior to the XXIVth IAU General Assembly the announcement of new planetary satellites was carried solely by the IAU Circulars issued by the Central Bureau for Astronomical Telegrams (CBAT). With the recent availability of large-format CCD arrays, a number of observing groups are now searching for new small planetary satellites that were beyond the reach of earlier photographic surveys. What started with the July 1999 discovery of three new Uranian satellites (IAUC 7230, IAUC 7248), following two 1997 Uranian satellite discoveries, has now become a flood with an additional 23 Jovian (one of which proved to be a rediscovery of the lost S/1975 J 1) and 12 Saturnian satellites. The requirement of publishing the astrometry and orbits for all these objects would have overwhelmed the IAU Circulars. At the XXIVth GA, it was decided that the IAU Circulars would henceforth contain a summary of the discovery with some initial astrometric observations and a preliminary orbit. The Minor Planet Electronic Circulars (MPECs, published by the Minor Planet Center) would then carry the orbits and the full set of astrometric observations. Since the XXIVth GA, the Minor Planet Center has concerned itself with announcing new discoveries of planetary satellites (in collaboration with CBAT, which is responsible for assigning designations to new discoveries), determining preliminary orbits, publishing follow-up astrometry and updating orbits as necessary and disseminating observational and orbital information via the MPECs and Minor Planet Circulars. Second-apparition astrometry has been obtained for the majority of the discoveries: of the 27 objects discovered before late 2001 (i.e., those that have had the opportunity to be recovered), all but one have been observed at a second apparition. Rio de Janeiro Observatory, CNPq, Brazil) Campaigns of observations of the planetary satellites were continued using a coronograph with a variable diameter occulting disk (Bourget, Veiga, Vieira-Martins: 2001, PASP, 113, 436). Observations were published: photographic observations of Helene (Veiga, Vieira-Martins: 2000, A & A S, 143, 405), photographic positions of the First Eight Satellites of Saturn (Veiga, Vieira-Martins: 1999, A & A S, 139, 305), CCD observations of Phoebe (Veiga, Vieira-Martins, Andrei: 2000, A & A S, 142, 81), CCD observations of the satellites of Uranus (Veiga, Vieira-Martins: 1999, A & A S, 138, 247) and CCD observations of Nereid (Veiga, C.H., Viera,Martins, R. and Le Guyader, Cl.: 1999, Astron. Astrophys. Suppl., 136, 445). 2) Processing of observations F. Franklin and K. Aksnes (2001, Astron. J, 122, 2734) have analyzed some 500 observations of mutual events of the Galilean satellites between 1908 and 1997 and have found clear evidence for a secular acceleration in Io's motion. The results imply that Io is now spiraling slowly inward, losing more orbital energy from internal dissipation than it gains from Jupiter's tidal torque. Sternberg Astronomical Institute (Lomonosov University, Moscow, Russia) An original approach was proposed and developed (Emelianov N.V. et al. : 2000, Astron. Astrophys. Suppl. Ser., 141, 433-447) to process photometric observations of the natural satellites during their mutual occultations and eclipses. The photometric data are reduced to the planetocentric rectangular coordinate differences of satellite pairs. With this method a treatment of the photometric observations of the Galilean satellites of Jupiter during their mutual occultations and eclipses in 1997 on the observatories of Kazakh republic, Russia and Ukraine was made and 44 mutual planetocentric positions of satellites were derived and published. Institute of Astronomy of Catania University (Italy) During the period July 1999 to June 2002 the Catania activity on Natural Planetary Satellites was mainly devoted to the analysis of the phenomena observed at M.G. Fracastoro during the PHEMU 97 campaign. After the reduction 28 lightcurves resulted good to provide elements useful to determine accurate photometric position. In the framework of their publication in the PHEMU 97 catalogue a study on the agreement between the predicted and observed characteristics of the lightcurves was published (Blanco et al.: 2001, Planetary and Space Science, 49, 31-34). U.S. Naval Observatory (Washington, DC, USA) HST astrometric observations of four inner satellites of Neptune, made in 1997, have been analyzed, and new mean motions for Proteus (NVIII), Larissa (NVII), Galatea (VI), and Despina (V) determined. A publication of the results is being prepared (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.: 1999, 31, 1229, 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.:1999, An Episodic Reddening of Triton, BAAS, 31, 1093). Institut de mecanique celeste/Bureau des longitudes (observatoire de Paris, France) Mutual events of the Saturnian satellites were preliminary analyzed (Arlot, J.-E.; Thuillot, W.; Ruatti, Ch.: 2002, Celestial Mechanics and Dynamical Astronomy, 81, 1-2, 193). An analysis of the CCD observations of the mutual events of the satellites of Saturn was made and direct positions were deduced (Vienne, A., Thuillot, W., Veiga, C.H., Arlot, J.-E., Vieira Martins, R..: 2001, Astron. Astrophys. 380, 727-733 ). Observations of Phoebe available were fitted to the theory in order to provide a new ephemeris. An analysis of the observations of the inner satellites of Jupiter was made (Vachier, F., Thuillot, W., Arlot, J.-E., Colas, F., Fienga, A.: 2001, Dynamical behaviour of the faint inner Jovian satellites, CELMEC III wokshop, Rome) 3) Ephemerides Sternberg Astronomical Institute (Lomonosov University, Moscow, Russia) The circumstances of mutual occultations and eclipses of Jupiter's Galilean satellites in 2002-2003 are pre-calculated and presented in Web-site of SAI (Emelianov N.: 2001, Astronomy and Geodesy in new millenium. Proceedings of International Conference "AstroKazan-2001", September 24-29, 2001, 111-113). Predictions of favorable circumstances to observe Saturn co-orbital satellites Janus and Epimetheus as they passed through superior conjunction from August 20, 2004 to June 1, 2005 were made and published. The apparent encounters of outer satellite of Jupiter were also pre-calculated and published (Emelianov N.V.: 2001, Solar System Research, 35, 209-211). Jet Propulsion Laboratory (Pasadena, California, USA) The work in the past three years has focused primarily on two areas: support and data analysis for the Galileo mission, determination of the orbits of the irregular satellites of Jupiter, Saturn, and Uranus. For the Galileo mission, models for the orbits of the Galilean and inner Jovian satellites have been continually improved. In conjunction with the orbit determination a new gravity field for the Jovian system was developed. The orbits of the Galileans, Amalthea, and Thebe were numerically integrated using an analytical theory for the orbits of Metis and Adrastea. The integration and theory are fit to an extensive set of Earthbased observations as well as data acquired by the Pioneer, Voyager, Ulysses, Cassini, and Galileo spacecraft. The spacecraft data is crucial to the gravity field development (Anderson, J. D., Jacobson, R. A., McElrath, T.P., Schubert, G., Moore, W. B. 1999. BAAS, 31, 4, 1181, Anderson, J. D., Schubert, G., Jacobson, R. A., Lau, E. L., and Moore, W. B., EGS, 2000 Conference, Nice, France, Anderson, J. D., Jacobson, R. A., McElrath, T. P., Schubert, G., Moore, W. B., and Thomas, P. C.: 2001, Icarus, 153, 157-161, Anderson, J. D., Jacobson, R. A., Lau, E. L., Moore, W. B., and Schubert, G.: 2001, J. Geophys. Res., 106(E12), 32963-32969, Anderson, J. D., Jacobson, R. A., Lau, E. L., Moore, W. B., Olsen, O., Schubert, G., and Thomas, P. C.: 2001, BAAS, 33, No.3, 1101, Anderson, J. D., Anabtawi, A., J. K., Jacobson, R. A., Lau, E. L., Schubert, G., and Moore, W. B.: 2002, paper P21B-01, Spring Meeting of the AGU, Jacobson, R. A.: 2001, The Planet, Satellites, and Magnetosphere, Boulder, Colorado, Jacobson, R. A.: 2001, BAAS, 33, No.3, 1039, Burns, J. A., Gladman, B. J., Nicholson, P. D., Jacobson, R. A., Carruba, V., Holman, M. J., and Kavelaars, J. J.: 2001, BAAS, 33, No.3, 1193, Schubert, G., Moore, W. B., Anderson, J. D., Jacobson, R. A., and Lau, E. L.: 2000, BAAS, 32, No.3, 1046). Since the last report 38 new irregular satellites have been discovered. Numerically integrated orbits for all shortly after their discovery are produced and have been continually improved as additional observations are made (Gladman, B., Kavelaars, J. J., Holman, M., Nicholson, P. D., Burns, J. A., Hergenrother, C.W., Petit, J-M., Marsden, B. G., Jacobson, R. A., Gray, W., and Grav, T.: 2001, letters to Nature, 412, 163-166, Jacobson, R. A.: 2001, BAAS, 33, No.3, 1191). The ephemerides of the outer satellites of Jupiter were improved (Jacobson, R. A.: 2000, BAAS, 32, No.2, 861, Jacobson, R. A.: 2000, AJ, 120, 2679-2686). In addition to the above, the satellite software system has been upgraded through maintaining and updating the observations and ephemeris database. Ephemerides for all 101 of the natural satellites (including the Moon) are provided to JPL and non-JPL users (the latter via the Horizons system). Institut de mecanique celeste/Bureau des longitudes (observatoire de Paris, France) The mutual events of the Galilean Satellites of Jupiter for 2002-2003 were calculated (Arlot, J.E.: 2002, 383, 719) and are available on the web site of IMCCE (http://www.imcce.fr/ Phemu03/ phemu03\_eng.html) together with an interactive software allowing the calculation of the local observational conditions. The mutual events including Amalthea are also available. Ephemerides of the newly discovered outer satellites of Jupiter and Saturn are also available on the web site of IMCCE. Institute of Applied Astronomy, (Saint-Petersbourg, Russia) The use of the observations of the Galilean satellites made at Nikolaev Observatory from 1962 to 1997 allowed to improve the ephemerides of Jupiter (Vasilyev M., Krasinsky G., Sveshnikov M., Gorel G., Gudkova L.: 2000, Trudy IPA RAN -Proceedings of Institute of Applied Astronomy-, 5, 176-189). 4) Theoretical works Institute of Applied Mathematics (Moscow, Russia) A series of theoretical results was published by Vashkov'yak M. A. on the evolution of orbits of the new distant irregular satellites of Jupiter, Saturn and Uranus. The evolution was mainly investigated by analytically solving Hill's double-averaged problem for the planet-Sun-satellite system and by numerically integrating the averaged equations. Having analysed the configuration and dynamics of the orbits of Uranus's five outer satellites, the possibility of their mutual crossings was revealed. Vashkov'yak M. A. offered a celestial-mechanical explanation for the absence of equatorial satellites of Uranus in the intermediate region between inner near-equatorial satellites and distant irregular satellites. Based on characteristic features of the orbital evolution of Saturn's new satellites he proposed their natural classification. For new outer satellites of Jupiter, Saturn, and Uranus the extreme eccentricities and inclinations, as well as the circulation periods of the pericenter arguments and of the longitudes of ascending nodes were determined (Vashkov'yak M.A.: 2001, Pisma v astronomicheskii zhurnal (In Russian), 27, N.6, 470-475, Vashkov'yak M.A.: 2001, Pisma v astronomicheskii zhurnal (In Russian), 27, N.7. P. 533-542, Vashkov'yak M.A.: 2001, Pisma v astronomicheskii zhurnal (In Russian), 27, N.7, 543-548, Vashkov'yak M.A.: 2001, Pisma v astronomicheskii zhurnal (In Russian), 27, N.6, 470-475 -Simultaneous English language translation of the journal "Pisma v astronomicheskii zhurnal" as "Astronomy Letters" ISSN 1063-7737 is distributed worldwide by the American Institute of Physics-). NAO RAL (Great-Britain) Numerical integration output of the 5 major Uranian satellites from the ephemerides was made: from a spectral analysis of 50 years data they have identified the major short-period perturbations and one of the secular perturbations. The remaining secular terms will have periods longer than the timespan of the fit. They are comparing the spectral analysis results with theory. Institut de mecanique celeste/Bureau des longitudes (observatoire de Paris, France) A brand new theory of the motion of the Galilean satellites of Jupiter was made thanks to frequency analysis and will be applied to make new ephemerides after fit to the available observations (Lainey V., Vienne A.,: 2001, Colloq. CELMECIII, Rome,Italy). A new numerical integration was performed for the motion of the satellites of Neptune (Le Guyader). The observations of Mimas were used to determinate the eccentricity of Tethys and to understand the Mimas-Tethys commensurability (Vienne A.: 2001, Ceres 2001 Workshop on Astrometry and Physics of Minor Planets from Observational Networks, Paris, Vienne A.,: 2001, Colloq. CELMEC III, Rome, Italy). 5) Satellites of asteroids Very few astrometric positions are available for the fit of a dynamical model for any discovered satellite of asteroid. Search for satellites of asteroids An analysis of the observations of several asteroids suspected of binarity was made in order to detect the signature of a satellite (Thuillot, W.: 2001, Ceres 2001 Workshop on Astrometry and Physics of Minor Planets from Observational Networks, Paris). Observational direct search were made (Merline et al.: 2001, DPS, 33, 5201) using adaptive optics (Close L.M. et al.: 2000, SPIE, 4007, 796) or by analysis of space data from NEAR flyby around 433 Eros (Merline et al.: 1999, LPI, 30, 2055). A discovery was made of a satellite around (45) Eugenia (named S/1998 (45) 1 "Petit-Prince") (Merline et al.: 1999, DPS, 31, 2006). Theoretical works The lack of astrometric positions did not allow to determine models for the motion of the satellites and theoretical works were devoted to the formation of such satellites (Richardson D.C. et al.: 2001, A & A S, 199, 2801, Durda and Bottke: 2001, DPS, 33, 5203, Michel, Benz, Tanga, Richardson: 2001, Sci, 294, 1696). 6) Miscellaneous A review of the possibility of small telescopes for the observation of Natural Planetary Satellites was made (Arlot, J.-E.: 2001, Annual Scientific Meeting of the Astronomische Gesellschaft at the Joint European and National Meeting JENAM 2001 of the European Astronomical Society and the Astronomische Gesellschaft at Munich, JD 03 02). In response to solicitations for input into the National Research Council's Solar System Exploration Decadal Study, for the period 2003-2013, a panel was formed to produce a "White Paper" on the needs of astrometry in the Solar System. (Pascu, Johnson, Rohde, Stone, Zacharias, Giorgini, Jacobson, Standish, Marsden, Ball). A new scale field in the Pleiades, containing 10 Hipparcos stars and 10 additional Tycho stars (on a 5x7 inch plate) was identified and used to redetermine the scale of the USNO 26-inch refractor. The new value agreed with the older value, but a substantial coma term was detected. This scale value is to be used for reduction of satellite observations made with the 26-inch. (Pascu, D., Winter, L., Zacharias, N., Wycoff, G.: 2001, BAAS, 33, 3). 7) Activities of the Working Group on Natural Planetary Satellites (J.E. Arlot, chairman) The activities of the working group on Natural planetary satellites were mainly dedicated to the maintenance of the data base of astrometric observations of the natural planetary satellites: - mutual events of the galilean satellites: most of the events observed during the past campaigns are available; the lightcurves are available for 1985 and 1991. - astrometric observations: most of the observations made in the countries of the former soviet union before 1990 are now available - standard data: an effort was made to provide data directly usable for theoretical purpose such as fit of theories or validation of ephemerides. - bibliographic data: all the astrometric data are documented through the data base of the papers where they were published. Theoretical papers are also included in the database. The site of the working group is available at the address: http://www.imcce.fr/iauwg.html The data base is available at the address: http://www.imcce.fr/nsdc.html