observations of Lempo over an observation arc of over 46 years have been documented. The earliest known precovery observations of Lempo have been found in photographic plates of the Siding Spring Observatory's Digitized Sky Survey from June 1974 and May and September 1976. Name The largest primary component of the triple system is named after Lempo from Finnish mythology. Originally worshiped as the god of love and fertility, he was later depicted as a devil, after Christianity came to Finland. Lempo brought down the hero Väinämöinen with the help of his two demon cohorts Hiisi and Paha, whose names denominate the smaller inner and outer components, respectively. The names were chosen on behalf of astronomer Bryan J. Holler. The official naming citation was published by the Minor Planet Center on 5 October 2017. Trinary system Lempo Lempo is a hierarchical triple (or trinary) system consisting of a central primary, which is itself a binary system of two similarly-sized components (Lempo and Hiisi), and a small satellite on a wide and eccentric circumbinary orbit (Paha). The structure of the hierarchy is discerned by denoting the apparent Lempo–Hiisi primary with the letter A and the smaller, outer companion Paha with the letter B; the individual primary components Lempo and Hiisi are distinguished as A1 and A2, respectively. The three components ordered from largest to smallest are Lempo, Hiisi, and Paha. Assuming spherical shapes with a uniform bulk density for all components, the system mass estimated based on the motion of Paha is . The orbital motion of the Lempo–Hiisi components gives somewhat a higher estimated mass of . This discrepancy is probably related to unaccounted gravitational interactions of the components in a complex triple system. Lempo is one of the only three trans-Neptunian multiple systems with more than two components; the other two are the dwarf planets Pluto and Haumea. The binary Kuiper belt object 385446 Manwë is suspected to have once been a hierarchical triple system similar to Lempo, but the orbit of its inner binary evolved by tides and became a contact binary. Hiisi Hiisi, officially designated (47171) Lempo II Hiisi, is the inner, second-largest component of the Lempo triple system, discovered last among the three. Together with the primary component Lempo, it forms the central binary Lempo–Hiisi which the outer component Paha revolves around. The existence of a third, inner component (or second companion) in the Lempo system was