The standard designation consists of the following parts, all of which are related to the date of discovery of the object: a 4-digit number indicating the year; a space; a letter to show the half-month; another letter to show the order within the half-month; and an optional number to indicate the number of times the second letter has been repeated in that half-month period.
The half-month of discovery is indicated using the following scheme:
Letter Dates Letter Dates A Jan. 1-15 B Jan. 16-31 C Feb. 1-15 D Feb. 16-29 E Mar. 1-15 F Mar. 16-31 G Apr. 1-15 H Apr. 16-30 J May 1-15 K May 16-31 L June 1-15 M June 16-30 N July 1-15 O July 16-31 P Aug. 1-15 Q Aug. 16-31 R Sept.1-15 S Sept.16-30 T Oct. 1-15 U Oct. 16-31 V Nov. 1-15 W Nov. 16-30 X Dec. 1-15 Y Dec. 16-31 I is omitted and Z is unusedThe order within the month is indicated using letters as follows:
A = 1st B = 2nd C = 3rd D = 4th E = 5th F = 6th G = 7th H = 8th J = 9th K = 10th L = 11th M = 12th N = 13th O = 14th P = 15th Q = 16th R = 17th S = 18th T = 19th U = 20th V = 21st W = 22nd X = 23rd Y = 24th Z = 25th I is omittedIf there are more than 25 discoveries in any one half-month period, the second letter is recycled and a numeral `1' is added to the end of the designation. If more than 50 discoveries, the second-letter is again recycled, with a numeral `2' appended after the second letter. Discoveries 76-100 have numeral `3' added, numbers 101-125 numeral `4', etc. When possible, these additional numbers should be indicated using subscript characters.
Thus the order of assignment of designations in a particular half-month
period is as follows:
1995 SA, 1995 SB, ..., 1995 SY, 1995 SZ,
1995 SA1, ...,
1995 SZ1, 1995 SA2, ..., 1995 SZ9,
1995 SA10, etc.
This scheme has been extended to pre-1925 discoveries--such designations
are indicated by the replacement of the initial digit of the year by
the letter `A'. Thus,
A904 OA is the first object designated that was
discovered in the second half of July 1904.
Survey Identifier Palomar-Leiden (1960) P-L First Trojan Survey (1971) T-1 Second Trojan Survey (1973) T-2 Third Trojan Survey (1977) T-3Example designations are
2040 P-L, 3138 T-1, 1010 T-2 and 4101 T-3.
In 1892 a system of provisional designations was introduced by the AN. A definitive number was subsequently given by the editors of the Berliner Astronomisches Jahrbuch to those objects for which reasonable orbital elements had been computed. The provisional designation scheme consisted initially of a year and a single letter: e.g., 1892 A, 1892 B, etc., omitting the letter `I'.
In 1893, the 25 available letters proved to be insufficient and a series of double letter designations was introduced: e.g. 1893 AA, 1893 AB, etc., omitting the letter `I'. The sequence of double letters was not restarted anew each year, so 1894 AQ followed 1893 AP (for example). In 1916, the letters reached ZZ and, rather than starting a series of triple-letter designations, the double-letter series was restarted with 1916 AA.
[NOTE: In old publications, it is common to see `J' as the omitted letter instead of `I'--the sequence going 1892 H, 1892 I, 1892 K, etc. Modern usage would consider 1892 I to be the same as 1892 J and it is this latter designation which is recorded.]
In the double-letter scheme it was not generally possible to insert new discoveries into the sequence once designations had been assigned in a subsquent year. The scheme used to get round this problem was rather clumsy and used a designation consisting of the year and a lower-case letter in a manner similar to the old provisional-designation scheme for comets. For example, 1915 a (note that there is a space between the year and the letter in order to distinguish this designation from the old-style comet designation 1915a), 1917 b. In 1914 designations of the form year plus Greek letter were used in addition.
During World War I the active observers at Simëis in the Crimea, deprived of official designations for their discoveries, assigned their own. The designations came in two forms: year + Greek capital sigma + letter(s); Greek capital sigma + number. The Greek capital sigma is indicated as SIGMA.
Other designation schemes used at Simëis and other observatories are listed elsewhere.
To summarise, the following forms of input are valid:
1915 SIGMA r, 1916 SIGMA ci
SIGMAmay be abbreviated to
SIGand the year is optional on the
SIGMA ciis a shorthand form for
1916 SIGMA ci).