A Possible Dynamically Cold Classical Contact Binary: (126719) 2002 CC249

Images of the Kuiper Belt object (126719) 2002 CC₂₄₉ obtained in 2016 and 2017 using the 6.5 m Magellan-Baade Telescope and the 4.3 m Discovery Channel Telescope are presented. A light curve with a periodicity of 11.87 ± 0.01 hr and a peak-to-peak amplitude of 0.79 ± 0.04 mag is reported. This high amplitude double-peaked light curve can be due to a single elongated body, but it is best explained by a contact binary system from its U-/V-shaped light curve. We present a simple full-width-at-half-maximum test that can be used to determine if an object is likely a contact binary or an elongated object based on its light curve. Considering that 2002 CC₂₄₉ is in hydrostatic equilibrium, a system with a mass ratio q_min = 0.6, and a density ρ_min = 1 g cm^-3, or less plausible a system with q_max = 1, and ρ_max = 5 g cm^-3 can interpret the light curve. Assuming a single Jacobi ellipsoid in hydrostatic equilibrium and an equatorial view, we estimate ρ ≥ 0.34 g cm^-3, and a/b = 2.07. Finally, we report a new color study showing that 2002 CC₂₄₉ displays an ultra red surface characteristic of a dynamically Cold Classical trans-Neptunian object.