Observations of small Solar System bodies

Observations of minor planets as well as comets and natural satellites of the Solar System are made by astronomical observatories all over the world and reported to the Minor Planet Center (MPC), a service of the International Astronomical Union. The MPC maintains a data base that stores all observations submitted by these registered observatories. An astrometric record consists of the position, brightness and timestamp of an observed object, besides additional information. The database contains more than 200 million records gathered over the past two centuries.^[2]

The MPC assigns a 3 digit observatory code for each observatory, also known as 'MPC-' or 'IAU codes'. The code is in the range 000 to Z99 and serves as a unique identifier for the reported observations. The MPC periodically published a revised "List Of Observatory Codes" with newly registered observatories in their Minor Planet Circulars. Over time, the number of astronomical observatories worldwide has been growing constantly and contains 2468 observatory codes as of November 2023^[update].^[3]

On numbering, often years later, the MPC determines the discovery among all the reported observations for an object. This does not need to be the earliest dated observation, also see precovery. The date of the selected observation will become the object's discovery date, and the corresponding observing astronomer or facility will become its discoverer.^[4] The discovery circumstances are given in the catalog of numbered minor planets.