5119 Imbrius, provisional designation: 1988 RA₁, is a Jupiter trojan from the Trojan camp, approximately 49 kilometers (30 mi) in diameter. It was discovered on 8 September 1988 by Danish astronomer Poul Jensen at the Brorfelde Observatory near Holbæk, Denmark.^[1] The dark Jovian asteroid has a rotation period of 12.8 hours.^[9] It was numbered in March 1992, and named from Greek mythology after Imbrius, who was killed by Greek archer Teucer during the Trojan War.^[11]

On the night this minor planet was discovered at Brorfelde Observatory, Poul Jensen also discovered the Jupiter trojan (6002) 1988 RO,^[12] the 12-kilometer size main-belt asteroid (9840) 1988 RQ₂,^[13] as well as (12689) 1988 RO₂, (14364) 1988 RM2, (14837) 1988 RN₂, and (24664) 1988 RB₁, all main-belt asteroids of inner, middle and outer region of the asteroid belt, respectively.

A first precovery was taken at Palomar Observatory in December 1954, extending the asteroid's observation arc by 34 years prior to its discovery.^[1]

Imbrius is a dark Jovian asteroid in a 1:1 orbital resonance with Jupiter. It is located in the trailering Trojan camp at the Gas Giant's L₅ Lagrangian point, 60° behind its orbit (see Trojans in astronomy). It is also a non-family asteroid of the Jovian background population.^[5] It orbits the Sun at a distance of 4.6–5.8 AU once every 11 years and 10 months (4,333 days; semi-major axis of 5.2 AU). Its orbit has an eccentricity of 0.11 and an inclination of 16° with respect to the ecliptic.^[3]

This minor planet was numbered on 18 March 1992 (M.P.C. 19840).^[11] On 29 November 2021, IAU's Working Group for Small Bodies Nomenclature named it from Greek mythology after Imbrius, son of Mentor and husband of King Priam's daughter Medesicaste. Imbrius was killed by the Greek archer Teucer during the Trojan War.^[1][2]

Imbrius is an assumed, carbonaceous C-type asteroid, while most larger Jupiter trojans are D-types. It has a typical V–I color index of 0.97.^[9]