Explanation Of Orbital Elements
The quantities given in orbital elements published in the
Minor Planet Circulars
Minor Planet Electronic Circulars
have the following meanings (for a detailed explanation of the physical
meaning of these quantities, and on any relationships between different
quantities, you are referred to standard textbooks on celestial
- The epoch of osculation of the orbital elements.
- Mean anomaly at the epoch.
- Date of perihelion passage.
- Mean daily motion (in degrees/day).
- Semimajor axis (in AU).
- Reciprocal semimajor axis (in 1/AU).
- Perihelion distance (in AU).
- Orbital eccentricity.
- Orbital period (in years).
- The J2000.0 argument of perihelion (in degrees).
- The J2000.0 longitude of the ascending node (in degrees).
- The J2000.0 inclination (in degrees).
- P and Q vectors
- The vectors P and Q are an alternate form of representing the angular
elements Peri., Node and Incl. For an explanation of how to convert between
the two sets of quantities you are referred to standard celestial mechanics
- Uncertainty parameter.
Not all of these quantities will be given with every orbit, but enough
information will always be given to describe an orbit completely.
The following two quantities are not orbital elements but are generally
given with them.
- Absolute visual magnitude. A table converting
H to a diameter is available.
- Slope parameter. For an explanation of the H,G magnitude system
refer to Application of Photometric Models to Asteroids,
Bowell et al., in Asteroids II, 524-556 (published by
the University of Arizona Press, ISBN 0-8165-1123-3) and the