Light Curves of Dwarf Plutonian Planets and other Large Kuiper Belt Objects: Their Rotations, Phase Functions, and Absolute Magnitudes

I report new time-resolved light curves and determine the rotations and phase functions of several large Kuiper Belt objects, which includes the dwarf planet Eris (2003 UB₃₁₃). Three of the new sample of 10 trans-Neptunian objects display obvious short-term periodic light curves. (120348) 2004 TY₃₆₄ shows a light curve which if double-peaked has a period of 11.70 ± 0.01 hr and a peak-to-peak amplitude of 0.22 ± 0.02 mag. (84922) 2003 VS₂ has a well-defined double-peaked light curve of 7.41 ± 0.02 hr with a range of 0.21 ± 0.02 mag. (126154) 2001 YH₁₄₀ shows variability of 0.21 ± 0.04 mag with a possible 13.25 ± 0.2 hr single-peaked period. The seven new Kuiper Belt objects in the sample which show no discernible variations within the uncertainties on short rotational timescales are (148780) 2001 UQ₁₈, (55565) 2002 AW₁₉₇, (119979) 2002 WC₁₉, (120132) 2003 FY₁₂₈, (136108) Eris 2003 UB₃₁₃, (90482) Orcus 2004 DW, and (90568) 2004 GV₉. Four of the 10 newly sampled Kuiper Belt objects were observed over a significant range of phase angles to determine their phase functions and absolute magnitudes. The three medium- to large-sized Kuiper Belt objects 2004 TY₃₆₄, Orcus, and 2004 GV₉ show fairly steep linear phase curves (∼0.18 to 0.26 mag deg^-1) between phase angles of 0.1° and 1.5°. This is consistent with previous measurements obtained for moderately sized Kuiper Belt objects. The extremely large dwarf planet Eris (2003 UB ₃₁₃) shows a shallower phase curve (0.09 ± 0.03 mag deg^-1) which is more similar to the other known dwarf planet Pluto. It appears that the surface properties of the largest dwarf planets in the Kuiper Belt may be different than the smaller Kuiper Belt objects. This may have to do with the larger objects' ability to hold more volatile ices, as well as sustain atmospheres. Finally, it is found that the absolute magnitudes obtained using the phase slopes found for individual objects are a few tenths of magnitudes different than that given by the Minor Planet Center.