5244 Amphilochos is a mid-sized

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 at the

Palomar Observatory Palomar Observatory is an astronomical research observatory in San Diego County, California, United States, in the Palomar Mountain Range. It is owned and operated by the California Institute of Technology (Caltech). Research time at the observat ...

during the second Palomar–Leiden Trojan survey in 1973, and was later named after the seer Amphilochus from Greek mythology. The 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. ...

is likely elongated in shape 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 7.8 hours.

Discovery

''Amphilochos'' was discovered on 29 September 1973, by Dutch astronomer couple Ingrid and Cornelis van Houten at Leiden, on

photographic plate Photographic plates preceded photographic film as a capture medium in photography, and were still used in some communities up until the late 20th century. The light-sensitive emulsion of silver salts was coated on a glass plate, typically thinn ...

s taken by astronomer Tom Gehrels at the

in California. The body's observation arc begins with a

precovery In astronomy, precovery (short for pre-discovery recovery) is the process of finding the image of an object in images or photographic plates predating its discovery, typically for the purpose of calculating a more accurate orbit. This happens mos ...

taken at Palomar in April 1955, more than 18 years prior to its official discovery observation.

Palomar–Leiden Trojan survey

Despite being discovered during the second Palomar–Leiden Trojan survey in 1973, ''Amphilochos'' has not received a provisional

survey designation Provisional designation in astronomy is the naming convention applied to astronomical objects immediately following their discovery. The provisional designation is usually superseded by a permanent designation once a reliable orbit has been calcu ...

prefixed with "T-2". The survey was a fruitful collaboration between the Palomar and Leiden observatories during the 1960s and 1970s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where

astrometry Astrometry is a branch of astronomy that involves precise measurements of the positions and movements of stars and other celestial bodies. It provides the kinematics and physical origin of the Solar System and this galaxy, the Milky Way. His ...

was carried out. The trio are credited with the discovery of several thousand asteroids.

Orbit and classification

''Amphilochos'' is a dark Jovian

in a 1:1 orbital resonance with Jupiter. It is located in the leading

at the Gas Giant'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 on its orbit . It is also a non- family asteroid of the Jovian background population. It orbits the Sun at a distance of 5.0–5.3 AU once every 11 years and 9 months (4,297 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 5.17 AU). Its orbit has an eccentricity of 0.03 and an inclination of 6 ° with respect to the ecliptic.

Naming

This minor planet was named from Greek mythology after the seer Amphilochus, son of Amphiaraus. After the Trojan War, he was warned by a vision which saved his life as he returned to the Trojan shore before the Greek fleet departed. Amphilochus lived together with

Calchas Calchas (; grc, Κάλχας, ''Kalkhas'') is an Argive mantis, or "seer," dated to the Age of Legend, which is an aspect of Greek mythology. Calchas appears in the opening scenes of the ''Iliad'', which is believed to have been based on a war ...

''(see 4138 Kalchas)'' in Asia Minor. The official naming citation 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 ...

on 26 February 1994 ().

Physical characteristics

''Amphilochos'' is an assumed C-type asteroid, while the majority of larger Jupiter trojans are D-types. It has an untypically low V–I color index of 0.77 ''(see table below)''.

Rotation period

In September 2010, a first rotational lightcurve of ''Amphilochos'' was obtained from photometric observations in the R-band by astronomers at the

Palomar Transient Factory The Palomar Transient Factory (PTF, obs. code: I41), was an astronomical survey using a wide-field survey camera designed to search for optical transient and variable sources such as variable stars, supernovae, asteroids and comets. The projec ...

. Lightcurve analysis gave a

of 9.787 hours with a brightness variation of 0.51 magnitude (). The best-rated lightcurve with a well-defined period of hours and a high amplitude of 0.79 magnitude was obtained by Robert Stephens 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 ...

in Landers, California, in May 2015. A high brightness amplitude typically indicates that the body has a non-spherical shape. In August 2015, observations by the ''Kepler'' space telescope during its K2 mission gave another two lightcurves with a concurring period of 9.578 and 9.797 hours with a brightness variation of 0.73 and 0.67 magnitude, respectively (). The ''Collaborative Asteroid Lightcurve Link'' (CALL), labels the period determination for this asteroid as ambiguous.

Diameter and albedo

According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, ''Amphilochos'' measures 36.69 kilometers in diameter and its surface has an albedo of 0.091, while the ''Collaborative Asteroid Lightcurve Link'' assumes a standard albedo for a carbonaceous asteroid of 0.057 and calculates a diameter of 35.79 kilometers based on an absolute magnitude of 10.96.

Notes

References

External links

Asteroid Lightcurve Database (LCDB)
query form

)
Dictionary of Minor Planet Names
Google books

– Minor Planet Center * * {{DEFAULTSORT:Amphilochos 005244 Discoveries by Cornelis Johannes van Houten Discoveries by Ingrid van Houten-Groeneveld Discoveries by Tom Gehrels Named minor planets 19730929