One Million Asteroid, Comet, and Satellite Orbits

(Oct 2020) With the publication of 14 Oct's Daily Orbit Update Minor Planet Electronic Circular (MPEC), the Minor Planet Center's orbit catalog passed the one million small bodies milestone. Congratulations to the MPC and worldwide orbit computers, asteroid, comet, and satellite observers, and enthusiasts everywhere.

The MPC is the world's data collection and distribution center for all small body observations made worldwide. Teams of observers submit tracklets, short observation spans of positions and times of unknown moving objects, to the MPC. The MPC's main and most time-consuming job is linking these tracklets together and computing the resulting orbits. Often times the tracklets can be linked to other tracklets from close in time, and this allows for more rigorous checks and linkages to other tracklets in the past.

Some tracklets cannot be immediately identified and are placed in the MPC's isolated tracklet file. This file is publicly available, and other worldwide orbit computers can try their hand at linking. In recent years, hundreds of thousands of individual linkages have been made by orbit computers outside of the MPC. This has in turn helped the MPC produce this catalog of the millionth orbit.

It is important to remember that while the MPC handles observations of NEOs and comets, the majority of the work performed there is on maintaining and updating the catalog of routine main-belt minor planets. However, being able to identify moving object observations with the now millions of known object orbits helps the MPC and the observing community rapidly recognize new NEO discoveries for closer study.