Half-month
A half-month is a unit of time typically used in astronomy. Each month is separated into two parts:
- days 1–15,
- day 16 until the end of the month.
Unidentified celestial objects, such as comets and asteroids, are given designations that contains the half-month as a letter of the English alphabet. For example, an object seen in the second half of January would be identified with the letter B; if seen in the first half of February, the letter would be C. The letter I is not used, to prevent confusion with the number 1. Instead, the letters proceed from H (April 16-30) to J (May 1-15).
| Half-month | ||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| A | B | C | D | E | F | G | H | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | |
| Jan 1-15 | Jan 16-31 | Feb 1-15 | Feb 16-28/29 | Mar 1-15 | Mar 16-31 | Apr 1-15 | Apr 16-30 | May 1-15 | May 16-31 | Jun 1-15 | Jun 16-31 | Jul 1-15 | Jul 16-31 | Aug 1-15 | Aug 16-31 | Sep 1-15 | Sep 16-30 | Oct 1-15 | Oct 16-31 | Nov 1-15 | Nov 16-30 | Dec 1-15 | Dec 16-31 | |