- 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).
|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 16-30||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|