• Processing (Info)

  • 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  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
                        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)