Astronomy has Provisional Designation systems
to label objects that have just been discovered.
Distant objects can be immediately labeled by their position
on the Celestial Sphere, but for
newly-discovered solar system objects (minor planets),
a system independent of position is necessary.
A Survey-based Designator is often used,
but a general system has also been adopted
that uses the date and order of discovery.
- DDDD - four-digit year.
- AA - 2 letters, skipping the letter "I". The first letter indicates the half-month, days 1-15 being the first half (i.e., A for January 1-15, B for January 16-31, etc.), the second letter indicating the order of discovery, A for the first, B for the second, etc.
- number: if more than 25 objects are discovered, a 2 or higher integer indicates the 2nd letter has begun again at "A". E.g., the 26th object is given an A subscripted by a 2, the 27th, a B2, etc.
Example: 2016 EK156
- 2016 - year of discovery.
- E - discovered within March 1-15.
- K156 - 3910th object discovered in that period, i.e., K for 10th discovery after 25 × 156 previous discoveries.