Critical-list minor planet

A critical-list minor planet (critical list numbered object or critical object) is a numbered minor planet for which existing measurements of the orbit and position are especially in need of improvement.[1]

The IAU's Minor Planet Center (MPC) regularly publishes a list of these critical objects in their Minor Planet Electronic Circular.[2] The list typically contains asteroids that have been observed at a small number of apparitions, especially on opposition, or that have not been adequately observed for more than 10 years, while other observatories create their own, customized lists.[3] The MPC also lists currently observable critical objects on their website,[4] providing differently formatted lists of orbital elements to the worldwide astrometric community.[5]

Lowell Observatory publishes their own critical list, distinctly different from the MPC, instead focusing on objects with high ephemeris uncertainty. Specifically, objects with computed ephemeris uncertainty greater than 2 arcseconds over the next 10 years, and objects whose orbits degrade significantly when temporally isolated observations are ignored, are included in the list.[3]

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