T. Dobosz, J. G. Greenhill, Marcelo Assafin, Bruno Sicardy, D. Buckley, W. Beisker, Greg Bolt, F. Benard, V. Batista, J.-P. Teng-Chuen-Yu, François Colas, Alain Doressoundiram, C. Gruhn, J. Broughton, J. Lecacheux, S. Mathers, Julio Camargo, Roberto Vieira-Martins, D. Gault, A. Peyrot, A. H. Andrei, J. Biggs, C. De Witt, B. Lade, S. Dieters, Dave Herald, Felipe Braga-Ribas, D. N. da Silva Neto, R. Groom, Y. Boissel, E. Frappa, Thomas Widemann, S. Kerr, F. Roques, Raoul Behrend, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Institut Universitaire de France (IUF), Ministère de l'Education nationale, de l’Enseignement supérieur et de la Recherche (M.E.N.E.S.R.), Craigie, Reedy Creek, Bankstown, International Occulting and Timing Association (IOTA), International Occulting and Timing Association, Astronomical Association of Queensland (AAQ), Association astronomique de la Réunion (AAR), Association astronomique de la Réunion, Euraster, International Occultation Timing Association European Section (IOTA ES), International Occultation Timing Association European Section, South African Astronomical Observatory (SAAO), Institut de Mécanique Céleste et de Calcul des Ephémérides (IMCCE), Centre National de la Recherche Scientifique (CNRS)-Université de Lille-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Springbok, International Amateur Sternwarte (IAS), International Amateur Sternwarte, Institut d'Astrophysique de Paris (IAP), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Perth Observatory, School of Mathematics and Physics, University of Tasmania [Hobart, Australia] (UTAS), Astronomical Society of Western Australia (ASWA), Canberra Astronomical Society, Stockport Observatory, Southern Cross Observatory, Observatório do Valongo/UFRJ [Rio de Janeiro], Universidade Federal do Rio de Janeiro (UFRJ), Observatório Nacional/MCT, Universidade Estadual da Zona Oeste (UEZO), Universidade Estadual da Zona Oeste, Geneva Observatory, University of Geneva [Switzerland], Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), and Université de Genève = University of Geneva (UNIGE)
The original publication is available at http://iopscience.iop.org/1538-3881/; International audience; Pluto and its main satellite, Charon, occulted the same star on 2008 June 22. This event was observed from Australia and La Réunion Island, providing the east and north Charon Plutocentric offset in the sky plane (J2000): X= + 12,070.5 ± 4 km (+ 546.2 ± 0.2 mas), Y= + 4,576.3 ± 24 km (+ 207.1 ± 1.1 mas) at 19:20:33.82 UT on Earth, corresponding to JD 2454640.129964 at Pluto. This yields Charon's true longitude L= 153.483 ± 0fdg071 in the satellite orbital plane (counted from the ascending node on J2000 mean equator) and orbital radius r= 19,564 ± 14 km at that time. We compare this position to that predicted by (1) the orbital solution of Tholen & Buie (the "TB97" solution), (2) the PLU017 Charon ephemeris, and (3) the solution of Tholen et al. (the "T08" solution). We conclude that (1) our result rules out solution TB97, (2) our position agrees with PLU017, with differences of ΔL= + 0.073 ± 0fdg071 in longitude, and Δr= + 0.6 ± 14 km in radius, and (3) while the difference with the T08 ephemeris amounts to only ΔL= 0.033 ± 0fdg071 in longitude, it exhibits a significant radial discrepancy of Δr= 61.3 ± 14 km. We discuss this difference in terms of a possible image scale relative error of 3.35 × 10-3in the 2002-2003 Hubble Space Telescope images upon which the T08 solution is mostly based. Rescaling the T08 Charon semi-major axis, a = 19, 570.45 km, to the TB97 value, a = 19636 km, all other orbital elements remaining the same ("T08/TB97" solution), we reconcile our position with the re-scaled solution by better than 12 km (or 0.55 mas) for Charon's position in its orbital plane, thus making T08/TB97 our preferred solution.