Observations of the Centaur 1999 UG 5 : Evidence of a Unique Outer Solar System Surface (original) (raw)

The outer solar system body 1999 UG 5 is a Centaur of medium brightness and slightly redder color when compared to other Centaurs. Similar to at least of the known Centaurs, it is a Saturn-crosser with 1 5 a mean orbital distance between Saturn and Uranus. We present optical photometry data and near-IR spectra obtained during 2000 September, November, and December. We find a rotation period of hr with 13.41 ‫ע‬ 0.04 an amplitude of mag and a phase curve with a Lumme-Bowell G value of. BVRI 0.102 ‫ע‬ 0.005 Ϫ0.13 ‫ע‬ 0.02 colors are reported, and they confirm the red spectral gradient observed previously. Our spectra reveal that this redward slope extends into near-IR wavelengths and indicates possible localized differences in the surface composition.