Export Format for Minor-Planet Orbits
This document describes the format used for both perturbed and perturbed orbits of minor planets, as used in the Extended Computer Service and in the Minor Planet Ephemeris Service.Orbital elements for minor planets are heliocentric.
The column headed `F77' indicates the Fortran 77 format specifier that should be used to read the specified value.
Columns F77 Use
1 - 7 a7 Number or provisional designation
(in packed form)
9 - 13 f5.2 Absolute magnitude, H
15 - 19 f5.2 Slope parameter, G
21 - 25 a5 Epoch (in packed form, .0 TT)
27 - 35 f9.5 Mean anomaly at the epoch, in degrees
38 - 46 f9.5 Argument of perihelion, J2000.0 (degrees)
49 - 57 f9.5 Longitude of the ascending node, J2000.0
(degrees)
60 - 68 f9.5 Inclination to the ecliptic, J2000.0 (degrees)
71 - 79 f9.7 Orbital eccentricity
81 - 91 f11.8 Mean daily motion (degrees per day)
93 - 103 f11.7 Semimajor axis (AU)
106 i1 Uncertainty parameter, U
If this column contains `E' it indicates
that the orbital eccentricity was assumed.
For one-opposition orbits this column can
also contain `D' if a double (or multiple)
designation is involved or `F' if an e-assumed
double (or multiple) designation is involved.
108 - 116 a10 Reference
118 - 122 i5 Number of observations
124 - 126 i3 Number of oppositions
For multiple-opposition orbits:
128 - 131 i4 Year of first observation
132 a1 '-'
133 - 136 i4 Year of last observation
For single-opposition orbits:
128 - 131 i4 Arc length (days)
133 - 136 a4 'days'
138 - 141 f4.2 r.m.s residual (")
143 - 145 a3 Coarse indicator of perturbers
(blank if unperturbed one-opposition object)
147 - 149 a3 Precise indicator of perturbers
(blank if unperturbed one-opposition object)
151 - 160 a10 Computer name
There may sometimes be additional information beyond column 160
as follows:
162 - 165 z4.4 4-hexdigit flags
The bottom 6 bits (bits 0 to 5) are used to encode
a value representing the orbit type (other
values are undefined):
Value
2 Aten
3 Apollo
4 Amor
5 Object with q < 1.665 AU
6 Hungaria
7 Phocaea
8 Hilda
9 Jupiter Trojan
10 Centaur
14 Plutino
15 Other resonant TNO
16 Cubewano
17 Scattered disk
Additional information is conveyed by
adding in the following bit values:
Bit Value
6 64 Unused
7 128 Unused
8 256 Unused
9 512 Unused
10 1024 Unused
11 2048 Object is NEO
12 4096 Object is 1-km (or larger) NEO
13 8192 1-opposition object seen at
earlier opposition
14 16384 Critical list numbered object
15 32768 Object is PHA
Note that the orbit classification is
based on cuts in osculating element
space and is not 100% reliable.
167 - 194 a Readable designation
195 - 202 i8 Date of last observation included in
orbit solution (YYYYMMDD format)
