• MPC Preparation (Info)

  • Packed Provisional and Permanent Designations

    This document describes the packed forms for provisional and permanent designations.


    Provisional Designations

    The provisional designation stored on the orbit and observations is stored in a 7-character packed format that saves space and makes sorting easier.

    Minor Planets

    A description of the format of provisional designations is available.

    The first two digits of the year are packed into a single character in column 1 (I = 18, J = 19, K = 20). Columns 2-3 contain the last two digits of the year. Column 4 contains the half-month letter and column 7 contains the second letter. The cycle count (the number of times that the second letter has cycled through the alphabet) is coded in columns 5-6, using a letter in column 5 when the cycle count is larger than 99. The uppercase letters are used, followed by the lowercase letters.

    Where possible, the cycle count should be displayed as a subscript when the designation is written out in unpacked format.

       Examples:
       J95X00A = 1995 XA
       J95X01L = 1995 XL1
       J95F13B = 1995 FB13
       J98SA8Q = 1998 SQ108
       J98SC7V = 1998 SV127
       J98SG2S = 1998 SS162
       K99AJ3Z = 2099 AZ193
       K08Aa0A = 2008 AA360
       K07Tf8A = 2007 TA418
    
    Survey designations of the form 2040 P-L, 3138 T-1, 1010 T-2 and 4101 T-3 are packed differently. Columns 1-3 contain the code indicating the survey and columns 4-7 contain the number within the survey.
       Examples:
       2040 P-L  = PLS2040
       3138 T-1  = T1S3138
       1010 T-2  = T2S1010
       4101 T-3  = T3S4101
    

    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. 3140113 - 620,000 = 2520113 = 10*62^3 + 35*62^2 + 36*62^1 + 61*62^0).
    • (15396335) is represented as ~zzzz (i.e. 15396335 - 620,000 = 14776335 = 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".