(15789) 1993 SC is a trans-Neptunian object of the plutino class. The discovery was made in 1993 at the La Palma Observatory with the Isaac Newton Telescope. The dwarf planet candidate measures approximately 400 km in diameter. It was the second plutino to receive an MPC number. ^[1]

KBO's found in 1993 include: (15788) 1993 SB, (15789) 1993 SC, (181708) 1993 FW, (385185) 1993 RO and 1993 RP.

1993 SC orbits the Sun at a distance of 32.2-46.1 AU one per 247 Earth years (90,254 days, semi-major axis of 39.4 AU). Its orbit has an eccentricity of 0.183 and an inclination of 5.166° respective to the elliptic. Its observation arc began with Mauna Kea Observatories in 1993.

1993 SC is a trans-Neptunian object and belongs to the plutinos, a large group of objects named after their largest member, Pluto. These resonant trans-Neptunian objects stay in a 2:3 mean-motion orbital resonance with Neptune, orbiting exactly two times the sun for every three orbits Neptune does and are therefore protected from Neptune's scattering effect. Plutinos are located in the inner ridge of the Kuiper belt, a large disc of mostly non-resonant trans-Neptunian objects.

1993 SC was numbered by the Minor Planet Center on 28 April 2000, receiving the number (15789) in the minor planet catalog. As of 2018, it has not been named. according to the established naming conventions, it will get a mythological name associated with the underworld.

1993 SC has a very-red surface color (RR) on the visible part of the spectrum with B-V and V-R color indices of 1.190 ± 0.020 and 0.660 ± 0.030 respectively for a combined B-R magnitude of 1.78. A red surface color is typically represented with the association of tholins, polymer-like organic compounds, formed by long exposures to solar and cosmic radiation.

In 2019, a rotational lightcurve has been done. Lightcurve shows only small deviations, suggesting it is a spheroid with small albedo spots and hence a dwarf planet. However, its density might be high as 1.66, making it certainly a dwarf planet, but it might have a companion fourth the size of it, and its mass will be calculated.

Based on a general magnitude-to-diameter conversion, 1993 SC measures 328 km in diameter with an geometric albedo of 0.033. Michael E. Brown and Johnston's Archive give 1993 SC diameters of 398 km and 270 km with albedos of 4 and 0.035 respectively. On its website, Michael E. Brown lists 1993 SC as a "possible" dwarf planet, which is the category with the lowest certainly in its 5-class taxonomically system (see here).

• 15760 Albion
• List of trans-Neptunian objects
• Kuiper belt

• MPC: List of TNOs
• Grundy, W. M.; Noll, K. S.; Stephens, D. C. "Diverse albedos of small trans-neptunian objects." Icarus, Volume 176, Issue 1, p. 184-191 (07/2005) Abstract
• (15789) 1993 SC at the JPL Small-Body Database
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