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Constraints on Charon's orbital elements from the double stellar occultation of 2008 June 22


Sicardy, B and Bolt, G and Broughton, J and Dobosz, T and Gault, D and Kerr, S and Benard, F and Frappa, E and Lecacheux, J and Peyrot, A and Teng-Chuen-Yu, JP and Beisker, W and Boissel, Y and Buckley, D and Colas, F and de Witt, C and Doressoundiram, A and Roques, F and Widemann, T and Gruhn, C and Batista, V and Biggs, J and Dieters, S and Greenhill, J and Groom, R and Herald, D and Lade, B and Mathers, S and Assafin, M and Camargo, JIB and Vieira-Martins, R and Andrei, AH and da Silva Neto, DN and Braga-Ribas, F and Behrend, R, Constraints on Charon's orbital elements from the double stellar occultation of 2008 June 22, Astronomical Journal, 141, (2) Article 67. ISSN 0004-6256 (2011) [Refereed Article]

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DOI: doi:10.1088/0004-6256/141/2/67


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 ± 0◦̣071 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 ± 0◦̣071 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 ± 0◦̣071 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.

Item Details

Item Type:Refereed Article
Keywords:astrometry – Kuiper belt objects: individual (Pluto, Charon) – occultations – planets and satellites:
Research Division:Physical Sciences
Research Group:Astronomical sciences
Research Field:Galactic astronomy
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the physical sciences
UTAS Author:Dieters, S (Dr Stefan Dieters)
UTAS Author:Greenhill, J (Dr John Greenhill)
UTAS Author:Mathers, S (Mr Shevill Mathers)
ID Code:68680
Year Published:2011
Web of Science® Times Cited:14
Deposited By:Mathematics and Physics
Deposited On:2011-03-17
Last Modified:2017-11-06

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