ASTEROIDS
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 unused
The 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 omitted
If 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.