Export Format for Minor-Planet OrbitsThis 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 77/90/95/2003/2008 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 or a1 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 a9 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 This information has been updated 2014 July 16, for files created after 18:40 UTC on that day. Classification of distant-orbit types will resume after we ingest data from an outside collaborator. The bottom 6 bits (bits 0 to 5) are used to encode a value representing the orbit type (other values are undefined): Value 1 Atira 2 Aten 3 Apollo 4 Amor 5 Object with q < 1.665 AU 6 Hungaria 7 Phocaea [Not currently used] 8 Hilda 9 Jupiter Trojan 10 Distant object Additional information is conveyed by adding in the following bit values: Bit Value 6 64 Unused or internal MPC use only 7 128 Unused or internal MPC use only 8 256 Unused or internal MPC use only 9 512 Unused or internal MPC use only 10 1024 Unused or internal MPC use only 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. Note also that certain of the flags are for internal MPC use and are not documented. 167 - 194 a Readable designation 195 - 202 i8 Date of last observation included in orbit solution (YYYYMMDD format)