15502 Hypeirochus


15502 Hypeirochus is a Jupiter trojan from the Trojan camp, approximately in diameter. It was discovered on 14 July 1999, by astronomers with the Lincoln Near-Earth Asteroid Research at the Lincoln Lab's ETS near Socorro, New Mexico, in the United States. The dark Jovian asteroid has a rotation period of 15.1 hours and belongs to the [|90 largest Jupiter trojans].

Orbit and classification

Hypeirochus 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 Lagrangian point, 60° behind its orbit. It is also a non-family asteroid of the Jovian background population.
It orbits the Sun at a distance of 5.0–5.2 astronomical units once every 11 years and 7 months. Its orbit has an eccentricity of 0.02 and an inclination of 17° with respect to the ecliptic. The body's observation arc begins with its first observation as at Palomar Observatory in January 1982, more than 16 years prior to its official discovery observation at Socorro.

Numbering and naming

This minor planet was numbered by the Minor Planet Center on 21 June 2000. It was named in April 2025 after Hypeirochus, a son of King Priam who was killed by Odysseus.

Physical characteristics

Hypeirochus is an assumed carbonaceous C-type asteroid. It has a V–I color index of 0.875.

Rotation period

In September 2009, a first rotational lightcurve of Hypeirochus was obtained from photometric observations by Linda French at the Cerro Tololo Inter-American Observatory in Chile. Lightcurve analysis gave a rotation period of hours with a brightness variation of 0.10 magnitude.
Since then, follow-up observations by Daniel Coley and Robert Stephens at the Center for Solar System Studies during 2013–2017 gave four more refined lightcurves, with the best-rated one from January 2017 showing a rotation period of hours and an amplitude of 0.26 magnitude.

Diameter and albedo

According to the surveys carried out by the Japanese Akari satellite and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Hypeirochus measures 50.86 and 53.10 kilometers in diameter and its surface has an albedo of 0.067 and 0.069, respectively. The Collaborative Asteroid Lightcurve Link assumes a standard albedo for a carbonaceous asteroid of 0.057 and calculates a diameter of 55.67 kilometers based on an absolute magnitude of 10.0.