Astrophysics (index)about

Provisional Designation

(way to designate newly discovered solar system objects)

Provisional Designation systems have been devised 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 (e.g., Minor Planets), a system independent of position is necessary. A Survey-based Designator is often used, but general systems have also been adopted that uses the date and order of discovery. The need for such a system stems from the huge number of objects discovered, and that mixed with the established discoveries are observations insufficient to rule out known objects or gleaning inadequate information to enable identification of the same object in the future.

The system for minor planets:

DDDD AAnumber
  • 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.

For Comets, a system is used that is different in detail, but is also based on the year.

Objects with provisional designations are referred to as Numbered Objects.

(astronomy,designation,solar system)

Referenced by:
101955 Bennu
Minor Planet
New Horizons (NF1)