(145451) 2005 RM43

' (provisional designation ') is a trans-Neptunian object that resides in the scattered disc region beyond the Kuiper belt. It was discovered on 9 September 2005, by American astronomers Andrew Becker, Andrew Puckett and Jeremy Kubica at Apache Point Observatory in Sunspot, New Mexico. It measures between approximately 500 and 650 kilometers in diameter.

Description
is considered likely to be a dwarf planet by both Brown and Tancredi. Based on an absolute magnitude of 4.4, the body's diameter could be anywhere in the range of 350 to 800 kilometres (km), depending on its albedo, the surface reflectivity of the object. Johnston's Archive gives an estimate of 584 km, based on an assumed albedo of 0.09. Brown estimates a diameter of 524 km, based on an absolute magnitude of 4.8 and an assumed albedo of 0.08. A stellar occultation by in December 2018 gave a minimum diameter of 458 km.

In 2018, two stellar occultations by were observed on 3 February and 24 December. Observations of the February occultation yielded a single chord length of 456 km. Observations of the December occultation yielded two positive chords, which suggest an approximate diameter of 644 km for.

has been observed 303 times over 17 oppositions, with precovery images dating back to 1976. The orbit is well determined with an uncertainty parameter of 2.