  The 2005 July 11 C313.2 stellar occultation by Charon was observed by three
separate research groups, including our own, at observatories throughout South
America. Here, the published timings from the three data sets have been
combined to more accurately determine the mean radius of Charon: 606.0 +/- 1.5
km. Our analysis indicates that a slight oblateness in the body (0.006 +/-
0.003) best matches the data, with a confidence level of 86%. The oblateness
has a pole position angle of 71.4 deg +/- 10.4 deg and is consistent with
Charon's pole position angle of 67 deg. Charon's mean radius corresponds to a
bulk density of 1.63 +/- 0.07 g/cm3, which is significantly less than Pluto's
(1.92 +/- 0.12 g/cm3). This density differential favors an impact formation
scenario for the system in which at least one of the impactors was
differentiated. Finally, unexplained differences between chord timings measured
at Cerro Pachon and the rest of the data set could be indicative of a
depression as deep as 7 km on Charon's limb.
