Packed Provisional and Permanent Designations¶

This document describes the packed forms for provisional and permanent designations used in MPC data files.

See also the Provisional Designations page for a description of the unpacked provisional designation formats and the Extended Packed Provisional Designation Scheme for the new base-62 scheme designed for the LSST era.

Provisional Designations¶

The provisional designation stored in the orbit and observations uses a 7-character packed format that saves space.

Minor Planets¶

A fulsome description of the packed format for the provisional designations of minor planets is provided on the provisional-designations page.

Comets¶

Columns 1-4 are as detailed above for minor planets. Columns 5-6 contain the order within the half-month period. Column 7 will normally be '0', except for split comets, when the fragment designation is stored there as a lower-case letter.

   Examples:
   1995 A1    = J95A010
   1994 P1-B  = J94P01b   refers to fragment B of 1994 P1
   1994 P1    = J94P010   refers to the whole comet 1994 P1
   2048 X13   = K48X130
   2033 L89-C = K33L89c
   2088 A103  = K88AA30   A3 = 103

Comet designations may also be given in a 12-character form, where columns 6-12 are as described above. Column 5 will contain a 'C', 'P', 'D' or 'X' (depending on the status and orbit type of the comet). For a numbered periodic comet, columns 1-4 contain the periodic-comet number, left-padded with zeroes. For other comets columns 1-4 contain blanks.

Natural Satellites¶

The packed provisional format for satellite designations is identical to the packed format for comet designations, with the restriction that the last column (either column 7 or 12, depending on the form) always contains "0".

Permanent Designations¶

The permanent designation stored on the orbit and observations is stored in a 5-character packed format that saves space and makes sorting easier.

Minor Planets¶

If the minor-planet number is less than 100000, then the number is stored as a zero-padded right-justified string. E.g., (3202) is stored as 03202, (50000) as 50000.

When the number is above 99999, the number MOD 10000 is stored in columns 2-5 of the string and the number DIV 10000 is represented by the letters A-Z (if between 10 and 35, inclusive) or a-z (if between 36 and 61, inclusive). E.g., (100345) is represented as A0345, (360017) as a0017, and (203289) as K3289.

Numbers above 619999 will be indicated using a tilde, ~, as the first character. The subsequent 4 characters will all be base-62 (0-9, then A-Z if between 10 and 35 inclusive, then a-z if between 36 and 61 inclusive) and used to store the target number MINUS 620,000.

E.g.

(620000) is represented as ~0000 (i.e. 620,000 - 620,000 = 0 = 0*62^3 + 0*62^2 + 0*62^1 + 0*62^0).
(620061) is represented as ~000z (i.e. 620,061 - 620,000 = 61 = 0*62^3 + 0*62^2 + 0*62^1 + 61*62^0).
(3140113) is represented as ~AZaz (i.e. 3,140,113 - 620,000 = 2,520,113 = 10*62^3 + 35*62^2 + 36*62^1 + 61*62^0).
(15396335) is represented as ~zzzz (i.e. 15,396,335 - 620,000 = 14,776,335 = 61*62^3 + 61*62^2 + 61*62^1 + 61*62^0).

Comets¶

Permanent designations for comets are only given to periodic comets seen to return (or for Centaur comets, seen at multiple apparitions). The comet number is stored zero-padded right-justified in columns 1-4. Column 5 usually contains "P", except for lost or defunct periodic comets when it contains "D".

Natural Satellites¶

Permanent designations for natural satellites are the Roman numerals. A permanent natural-satellite packed designation starts with a letter indicating to which planet the satellite belongs ("J" = Jupiter, "S" = Saturn, "U" = Uranus, "N" = Neptune), followed by a three-character zero-padded right-justified string containing the numerical representation of the Roman numeral, followed by "S". E.g., Jupiter XIII is represented as J013S, Saturn X as S010S and Neptune II as N002S.