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Object Classifications

This page describes the different Comet and Asteroid classifications. Credit for the descriptions goes to JPL Solar System Dynamics group.

Comet Orbit Classes

Abbreviation Title Description
COM Comet Comet orbit not matching any defined orbit class.
CTc Chiron-type Comet Chiron-type comet, as defined by Levison and Duncan (TJupiter > 3; a > aJupiter).
ETc Encke-type Comet Encke-type comet, as defined by Levison and Duncan (TJupiter > 3; a < aJupiter).
HTC Halley-type Comet* Halley-type comet, classical definition (20 y < P < 200 y).
HYP Hyperbolic Comet Comets on hyperbolic orbits (e > 1.0).
JFc Jupiter-family Comet Jupiter-family comet, as defined by Levison and Duncan (2 < TJupiter < 3).
JFC Jupiter-family Comet* Jupiter-family comet, classical definition (P < 20 y).
PAR Parabolic Comet Comets on parabolic orbits (e = 1.0).

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Asteroid Orbit Classes

Abbreviation Title Description
AMO Amor Near-Earth asteroid orbits similar to that of 1221 Amor (a > 1.0 AU; 1.017 AU < q < 1.3 AU).
APO Apollo Near-Earth asteroid orbits which cross the Earth's orbit similar to that of 1862 Apollo (a > 1.0 AU; q < 1.017 AU).
AST Asteroid Asteroid orbit not matching any defined orbit class.
ATE Aten Near-Earth asteroid orbits similar to that of 2062 Aten (a < 1.0 AU; Q > 0.983 AU).
CEN Centaur Objects with orbits between Jupiter and Neptune (5.5 AU < a < 30.1 AU).
HYA Hyperbolic Asteroid Asteroids on hyperbolic orbits (e > 1.0).
IEO Interior Earth Object An asteroid orbit contained entirely within the orbit of the Earth (Q < 0.983 AU).
IMB Inner Main-belt Asteroid Asteroids with orbital elements constrained by (a < 2.0 AU; q > 1.666 AU).
MBA Main-belt Asteroid Asteroids with orbital elements constrained by (2.0 AU < a < 3.2 AU; q > 1.666 AU).
MCA Mars-crossing Asteroid Asteroids that cross the orbit of Mars constrained by (1.3 AU < q < 1.666 AU; a < 3.2 AU).
OMB Outer Main-belt Asteroid Asteroids with orbital elements constrained by (3.2 AU < a < 4.6 AU).
PAA Parabolic Asteroid Asteroids on parabolic orbits (e = 1.0).
TJN Jupiter Trojan Asteroids trapped in Jupiter's L4/L5 Lagrange points (4.6 AU < a < 5.5 AU; e < 0.3).
TNO TransNeptunian Object Objects with orbits outside Neptune (a > 30.1 AU).

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