Minor Planet Center — the world’s clearinghouse for small-body orbits

The Minor Planet Center is the single worldwide location for receiving and distributing positional measurements of minor planets, comets, and the outer irregular natural satellites of the major planets. Founded in 1947, it operates at the Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, under Division F of the International Astronomical Union (IAU). Every observatory that wants to submit data must first obtain a unique three-character observatory code — a combination of letters and numbers — before any data can be submitted. Its flagship publication, the Minor Planet Circulars, has appeared continuously since that founding year, issued on the schedule of the full moon.

Key facts

  • Country: United States
  • Founded: 1947
  • Type: organization
  • Website: https://www.minorplanetcenter.net/

What the MPC does

The MPC’s core responsibilities are the identification, designation, and orbit computation for minor planets, comets, and outer natural satellites. It maintains master files of observations and announces discoveries through electronic circulars and its public website. Beyond astrometric positional data, the MPC also collects light-curve photometry of minor planets — brightness measurements over time that can reveal rotation rates and rough shapes.

The MPC’s operating funds come from a NASA Near-Earth Object Observations program grant. Much of its computing equipment was provided by the Tamkin Foundation of Los Angeles, whose support dates to around 1998, when the Tamkin Foundation Computing Network was established to give the MPC and the Central Bureau for Astronomical Telegrams shared computers for orbit-determination work. That network supported the MPC’s calculations through at least 2010.

Publications

The Minor Planet Circulars (ISSN 0736-6884), the MPC’s flagship print publication, have been issued since 1947 and appear generally on the date of each full moon. Alongside them, the Minor Planet Electronic Circulars carry ISSN 1523-6714 and are distributed electronically for time-sensitive announcements. Both series are formally prepared using the Tamkin Foundation Computer Network — a designation that still appears in the header of every published electronic circular.

History and institutional structure

The MPC was founded in 1947. Its first director, Paul Herget, pioneered the use of punched-card machines for orbital calculations and later extended that work to early electronic computers.

Brian Marsden directed the MPC from 1978 to 2006. The organisation sits within the IAU’s Division F, which was previously known as Division III and, before that, as Commission 20 (Positions and Motions of Minor Planets, Comets and Satellites).

In November 2017, the MPC proposed a new designation class to the IAU — the letter I for interstellar objects — and the IAU adopted it. The MPC assigned the first confirmed interstellar object detected in the solar system the designation 1I/2017 U1; it was subsequently named ‘Oumuamua.

Modernisation

In 2026, the MPC began transitioning its data-ingestion system to Amazon Web Services (AWS) as part of a broader modernisation of its data-processing infrastructure.

Did you know

  • When ‘Oumuamua was discovered in 2017, the MPC’s automated orbit-calculation software initially rejected multiple submitted observations. The system was built on the assumption that any solar-system object follows an elliptical or parabolic orbit; ‘Oumuamua’s measured orbital eccentricity was approximately 1.188, a value that had no precedent in the entire catalogue of known solar-system objects and that the software simply could not process. (johnstonsarchive.net)
  • The Minor Planet Electronic Circulars carry ISSN 1523-6714 and are formally prepared using what the MPC labels the ‘Tamkin Foundation Computer Network.’ That name — honouring the Los Angeles foundation that equipped the MPC with shared computing hardware around 1998 — still appears in the header of every electronic circular the MPC publishes. (minorplanetcenter.net)
  • Brian Marsden, who directed the MPC from 1978 to 2006, reportedly stepped down on the same day in 2006 that the IAU voted to reclassify Pluto as a dwarf planet. Marsden was said to have quipped that both he and Pluto had been ‘retired on the same day.’ (pbs.org)

Data sources

Data updated: 2026-10-29