DPS 35th Meeting, 1-6 September 2003
Session 15. Other Planetary Satellites II
Poster, Highlighted on, Wednesday, September 3, 2003, 3:00-5:30pm, Sierra Ballroom I-II

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[15.03] Revisiting the Question of Charon's Orbital Eccentricity

J. A. Miller (Univ. Maryland), D. J. Tholen (Univ. Hawaii)

We are continuing the analysis of adaptive optics observations of the Pluto-Charon system, with the goal of confirming the orbital eccentricity reported by Tholen and Buie (1997, Icarus 125, 245). Previous work on these data, obtained with the Hokupa'a adaptive optics system and Gemini North and reported by Tholen (2002, BAAS 34, 878), utilized only a portion of the full set of 352 images taken on 8 nights between 2001 and 2002, and was based on a preliminary calibration of the image scale and position angle of the detector relative to J2000 north.

For each of the three observing runs, independent calibrations were performed using the motion of an asteroid past a fixed stellar source to remove any minor differences in the way the instrument was mounted on the telescope for each run. The image scale of 0.02003 arcsec per pixel is good to better than 1 part in 1000, while the individual position angle determinations are good to at least 0.1 deg.

The preliminary analysis reported at last year's DPS meeting indicated consistency with the orbit determined from the HST observations acquired a decade ago, but a full error analysis had not yet been completed confirming or refuting the found nonzero eccentricity. That full error analysis is currently underway and will be reported at this year's meeting.

This work is supported in part by NSF Research Experiences for Undergraduates (REU) Grant 9987896 and NASA Grant NAG5-8989 to the University of Hawaii.

The author(s) of this abstract have provided an email address for comments about the abstract: millerja@wam.umd.edu

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Bulletin of the American Astronomical Society, 35 #4
© 2003. The American Astronomical Soceity.