1583 Antilochus is a large

Jupiter trojan The Jupiter trojans, commonly called trojan asteroids or simply trojans, are a large group of asteroids that share the planet Jupiter's orbit around the Sun. Relative to Jupiter, each trojan librates around one of Jupiter's stable Lagrange poin ...

from the

Greek camp This is a list of Jupiter trojans that lie in the Greek camp, an elongated curved region around the leading Lagrangian point (), 60 ° ahead of Jupiter in its orbit. All the asteroids at Jupiter's point have names corresponding to participants ...

, approximately in diameter. It was discovered on 19 September 1950, by Belgian astronomer

Sylvain Arend Sylvain Julien Victor Arend (6 August 1902 – 18 February 1992) was a Belgian astronomer born in Robelmont, Luxembourg province, Belgium. His main interest was astrometry. Together with Georges Roland, he discovered the bright comet C/1956 R ...

Uccle Observatory The Royal Observatory of Belgium (french: link=no, Observatoire Royal de Belgique, nl, Koninklijke Sterrenwacht van België), has been situated in the Uccle municipality of Brussels (Belgium) since 1890. It was first established in Saint-Josse ...

in Belgium, and later named after the hero

Antilochus In Greek mythology, Antilochus (; Ancient Greek: Ἀντίλοχος ''Antílokhos'') was a prince of Pylos and one of the Achaeans in the Trojan War. Family Antilochus was the son of King Nestor either by Anaxibia or Eurydice. He was the brot ...

from Greek mythology. The dark D-type asteroid belongs to the 20 largest Jupiter trojans and has a

rotation period The rotation period of a celestial object (e.g., star, gas giant, planet, moon, asteroid) may refer to its sidereal rotation period, i.e. the time that the object takes to complete a single revolution around its axis of rotation relative to the ...

of 15.9 hours. It forms an

asteroid pair An asteroid pair, or (if more than one body) an asteroid cluster, are asteroids which at some point in the past had very small relative velocities, and are typically formed either by a collisional break-up of a parent body, or from binary asteroids ...

with

3801 Thrasymedes 3801 Thrasymedes is a mid-sized Jupiter trojan from the Greek camp, approximately in diameter. It was discovered on 6 November 1985, by astronomers with the Spacewatch survey at the Kitt Peak National Observatory in Arizona, United States. T ...

Classification and orbit

''Antilochus'' is a dark Jovian

asteroid An asteroid is a minor planet of the inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; they are rocky, metallic or icy bodies with no atmosphere. ...

orbiting in the leading Greek camp at Jupiter's

Lagrangian point In celestial mechanics, the Lagrange points (; also Lagrangian points or libration points) are points of equilibrium for small-mass objects under the influence of two massive orbiting bodies. Mathematically, this involves the solution of th ...

, 60 ° ahead of its orbit in a 1:1 resonance . It is also a non- family asteroid in the Jovian background population. It orbits the Sun at a distance of 4.9–5.4 AU once every 11 years and 7 months (4,244 days;

semi-major axis In geometry, the major axis of an ellipse is its longest diameter: a line segment that runs through the center and both foci, with ends at the two most widely separated points of the perimeter. The semi-major axis (major semiaxis) is the long ...

of 5.13 AU). Its orbit has an eccentricity of 0.05 and an inclination of 29 ° with respect to the ecliptic. The asteroid was first observed as ' at Heidelberg Observatory in November 1926. The body's observation arc begins with its official discovery observation at Uccle in September 1950.

Asteroid pair

In 1993, Andrea Milani suggested that ''Antilochus '' forms an

with 3801 Thrasymedes, using the hierarchical clustering method (HCM), which looks for groupings of neighboring asteroids based on the smallest distances between them in the

proper orbital element __NOTOC__ The proper orbital elements or proper elements of an orbit are constants of motion of an object in space that remain practically unchanged over an astronomically long timescale. The term is usually used to describe the three quantitie ...

space. The astronomer describes the finding as statistically significant though difficult to account for by a regular collisional event. The Antilochus–Thrasymedes pair is not listed at the Johnston's archive.

Naming

This minor planet was named after prince

from Greek mythology. He was the youngest son of King

Nestor Nestor may refer to: * Nestor (mythology), King of Pylos in Greek mythology Arts and entertainment * "Nestor" (''Ulysses'' episode) an episode in James Joyce's novel ''Ulysses'' * Nestor Studios, first-ever motion picture studio in Hollywood, L ...

(), close friend of Greek hero Achilles () and commander of the Greek contingent of the Pylians during the Trojan War. The official was published by the

Minor Planet Center The Minor Planet Center (MPC) is the official body for observing and reporting on minor planets under the auspices of the International Astronomical Union (IAU). Founded in 1947, it operates at the Smithsonian Astrophysical Observatory. Function ...

in May 1952 ().

Physical characteristics

In the Tholen, Barucci and Tesco classification, ''Antilochus'' is a dark D-type asteroid, with a V–I color index of 0.95. The D-type is the most common spectral type among the Jupiter trojans.

Rotation period

In December 2009 and June 2016, rotational lightcurves of ''Antilochus'' were obtained from photometric observations by American astronomer Robert Stephens at the Santana Observatory and at the

Center for Solar System Studies This is a list of observatory codes (IAU codes or MPC codes) published by the Minor Planet Center. For a detailed description, ''see observations of small Solar System bodies''. List References * {{DEFAULTSORT:Observat ...

(CS3) in California. Lightcurve analysis gave a

of 31.52 and 31.54 hours with an amplitude of 0.09 and 0.11 magnitude, respectively (). Follow-up observations over a total of 11 nights by Stephens in August 2017 gave the so-far best-rated lightcurve with a period of hours – which corresponds to half the period solution of the former results – and a slightly higher brightness variation of 0.12 magnitude (). Stephen's period determination supersedes previously reported results by Vincenzo Zappalà (1985; 12 h), Federico Manzini (2007; 12 h) and

René Roy René Roy may refer to: * René Roy (economist) * René Roy (chemist) * René Roy (astronomer) This is a list of minor-planet discoverers credited by the Minor Planet Center with the discovery of one or several minor planets (such as near-Earth ...

(2009; 22.5 h) ().

Diameter and albedo

According to the surveys carried out by the Infrared Astronomical Satellite IRAS, the Japanese Akari satellite, and NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, ''Antilochus'' measures between 101.62 and 111.69 kilometers in diameter and its surface has an albedo between 0.053 and 0.063. The ''Collaborative Asteroid Lightcurve Link'' adopts the results obtained by IRAS, that is, an albedo of 0.0633 and a diameter of 101.62 kilometers, with Pravec's revised absolute magnitude of 8.59.

Classification and orbit

Asteroid pair

Naming

Physical characteristics

Rotation period

Diameter and albedo

Notes

References

External links