The Minor Planet Center is the official worldwide organization in charge of collecting observational data for minor planets, calculating their orbits and publishing this information via the Minor Planet Circulars. Under the auspices of the International Astronomical Union, it operates at the Smithsonian Astrophysical Observatory, which is part of the Center for Astrophysics along with the Harvard College Observatory. The MPC runs a number of free online services for observers to assist them in observing minor planets and comets. The complete catalogue of minor planet orbits may also be freely downloaded. In addition to astrometric data, the MPC collects light curve photometry of minor planets. A key function of the MPC is helping observers coordinate follow up observations of possible near-Earth objects via its NEO web form and blog. The MPC is also responsible for identifying, and alerting to, new NEOs with a risk of impacting Earth in the few weeks following their discovery .
The MPC periodically releases astrometric observations of minor planets, as well as of comets and natural satellites. These publications are the Minor Planet Circulars, the Minor Planet Electronic Circulars, and the Minor Planet Supplements. An extensive archive of publications in a PDF format is available at the Minor Planet Center's website. The archive's oldest publication dates back to 1 November 1977.
Minor Planet Circulars, established 1947, is a scientific journal that is generally published by the Minor Planet Center on the date of each full moon, when the number of reported observations are minimal due to the brighter night sky. The Circulars contain astrometric observations, orbits and ephemerides of minor planets, comets and certain natural satellites. The astrometric observations of comets are published in full, while the minor planet observations are summarised by observatory code. New numberings and namings of minor planets ', as well as numberings of periodic comets and natural satellites, are announced in the Circulars. New orbits for comets and natural satellites appear in the Circulars; new orbits for minor planets appear in the Minor Planets and Comets Orbit Supplement '.
The Minor Planet Electronic Circulars are published by the Minor Planet Center. They generally contain positional observations and orbits of unusual minor planets and all comets. Monthly lists of observable unusual objects, observable distant objects, observable comets and the critical list of numbered minor planets also appear on these circulars. Daily Orbit Update MPECs, issued every day, contain new identifications and orbits of minor planets, obtained over the previous 24 hours.
The Minor Planets and Comets Supplement is published on behalf of IAU's Division F by the Minor Planet Center.
The Minor Planets and Comets Orbit Supplement is published on behalf of IAU's Division F by the Minor Planet Center.
