DPS 2001 meeting, November 2001
Session 41. Asteroids Posters
Displayed, 9:00am Tuesday - 3:00pm Saturday, Highlighted, Friday, November 30, 2001, 9:00-10:30am, French Market Exhibit Hall

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[41.15] Analysis of the First Disk-Resolved Images of Ceres from Ultraviolet Observations with the Hubble Space Telescope

J. Wm. Parker, S. A. Stern (Southwest Research Institute), P. C. Thomas (Cornell University), M. C. Festou (Observatoire Midi-Pyrenees), W. J. Merline, E. F. Young (Southwest Research Institute), R. P. Binzel (Massachusetts Institute of Technology), L. A. Lebofsky (University of Arizona)

We present results from our analysis of Hubble Space Telescope Faint Object Camera observations of the asteroid 1 Ceres at near-, mid-, and far-UV wavelengths (3636, 2795, and 1621 Å, respectively). These images, with a resolution of 50 km on the surface of Ceres, provide us with an exciting view of Ceres and its properties. We will discuss the following findings:

* We have identified a large, ~250 km diameter surface feature, although its nature (crater, albedo variegation, or other effect) is uncertain.

* Limb fits to the images give semi-major and semi-minor axes of R1=484.8 ±5.1~km and R2=466.4 ±5.9~km, respectively, for the illumination-corrected projected ellipsoid.

* Full-disk integrated albedo measurements show that Ceres has a red spectral slope from the mid- to near-UV, and a significant blue slope shortward of the mid-UV.

* Minnaert surface fits to the near- and mid-UV images indicate an unusually large Minnaert parameter of k ~ 0.9, suggesting a more Lambertian than lunar-like surface.

Support for this work was provided by NASA through STScI Grant GO-05842.

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