Explanation Of Symbols

Designation (and name)

For numbered minor planet, this column contains the object's number and name (if named).

Prov. Des.

This is the object's provisional designation. Note that some of the low-numbered objects have old-style provisional designations, where the letters were recycled without regard to the calendar.

Ln

For Trojans, this column indicates whether the minor planet is near the L4 or the L5 point of the planet. L4 is 60° preceding the planet and L5 is 60° following.

q

Perihelion distance (in AU).

Q

Aphelion distance (in AU).

H

Absolute visual magnitude. A table converting H to a diameters is available.

M+, M-

The perpendicular distance to the earth's orbit when an object is at the earth's distance from the sun (in AU, omitted if greater than 0.3 AU). These quantities are given only for objects with perihelion distances less than 1.05 AU, although they are physically meaningful only when the orbit of an object intersects that of the earth. For Amor objects with perihelion distances less than 1.05 AU, a single value spans the two columns. For more information on these quantities, see Marsden, B. G. (1993) To Hit Or Not To Hit. In Proceedings of the Near-Earth-Object Interception Workship, pp. 67-71. Eds. G. H. Canavan, J. C. Solem and J. D. G. Rather. Los Alamos National Laboratory.

N+, N-

The distances of an object's nodal points from the earth's orbit (in AU, omitted if greater than 0.3 AU). N+ refers to the distance from the ascending node, N- to the distance from the descending node. These quantities are only given for objects with perihelion distances less than 1.3 AU. For more information on these quantities see Marsden (1993, ibid.).

Min.

This quantity, in AU and given only in the list of the larger potentially dangerous minor planets, is the minimum value of N+, N-, M+ and M-. If the minimum value corresponds to one of the value of N, it is followed by a `D' (to denote that the minimum value occurs at the descending node) or by an `A' (to denote that the minimum value occurs at the ascending node). Note that quantity does not give any information on actual close approaches--you should refer to lists of close encounters for such information. A value of 0.000 does NOT indicate that a hit will occur.

Epoch, M

These columns give the value of the mean anomaly for the specified epoch (in YYYYMMDD format).

Peri., Node, Incl.

The angular J2000.0 elements of the orbit, in degrees.

e

Orbital eccentricity.

a

Semimajor axis (in AU).

Opps.

Number of oppositions at which the object has been observed. If observations have been made at one opposition only, the arc length in days is given in parentheses.

Ref.

Reference to the published orbit, generally to the MPCs (= Minor Planet Circulars) or Icarus.

MPC