Minor Planet Electronic Circulars
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The Minor Planet Center (MPC) is the official body for observing and reporting on
minor planet According to the International Astronomical Union (IAU), a minor planet is an astronomical object in direct orbit around the Sun that is exclusively classified as neither a planet nor a comet. Before 2006, the IAU officially used the term ''minor ...
s under the auspices of the
International Astronomical Union The International Astronomical Union (IAU; , UAI) is an international non-governmental organization (INGO) with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and developmen ...
(IAU). Founded in 1947, it operates at the
Smithsonian Astrophysical Observatory The Smithsonian Astrophysical Observatory (SAO) is a research institute of the Smithsonian Institution, concentrating on Astrophysics, astrophysical studies including Galactic astronomy, galactic and extragalactic astronomy, cosmology, Sun, solar ...
.


Function

The Minor Planet Center is the official worldwide organization in charge of collecting observational data for
minor planet According to the International Astronomical Union (IAU), a minor planet is an astronomical object in direct orbit around the Sun that is exclusively classified as neither a planet nor a comet. Before 2006, the IAU officially used the term ''minor ...
s (such as
asteroid An asteroid is a minor planet—an object larger than a meteoroid that is neither a planet nor an identified comet—that orbits within the Solar System#Inner Solar System, inner Solar System or is co-orbital with Jupiter (Trojan asteroids). As ...
s), calculating their
orbit In celestial mechanics, an orbit (also known as orbital revolution) is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an ...
s and publishing this information via the ''
Minor Planet Circulars The Minor Planet Center (MPC) is the official body for observing and reporting on minor planets under the auspices of the International Astronomical Union (IAU). Founded in 1947, it operates at the Smithsonian Astrophysical Observatory. Functio ...
''. Under the auspices of the
International Astronomical Union The International Astronomical Union (IAU; , UAI) is an international non-governmental organization (INGO) with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and developmen ...
(IAU), it operates at the
Smithsonian Astrophysical Observatory The Smithsonian Astrophysical Observatory (SAO) is a research institute of the Smithsonian Institution, concentrating on Astrophysics, astrophysical studies including Galactic astronomy, galactic and extragalactic astronomy, cosmology, Sun, solar ...
, which is part of the
Center for Astrophysics Center or centre may refer to: Mathematics *Center (geometry), the middle of an object * Center (algebra), used in various contexts ** Center (group theory) ** Center (ring theory) * Graph center, the set of all vertices of minimum eccentricit ...
along with the
Harvard College Observatory The Harvard College Observatory (HCO) is an institution managing a complex of buildings and multiple instruments used for astronomical research by the Harvard University Department of Astronomy. It is located in Cambridge, Massachusetts, United St ...
. 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 (sometimes referred to as the "Minor Planet Catalogue") may also be freely downloaded. In addition to
astrometric Astrometry is a branch of astronomy that involves precise measurements of the positions and movements of stars and other celestial bodies. It provides the kinematics and physical origin of the Solar System and this galaxy, the Milky Way. History ...
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 object A near-Earth object (NEO) is any small Solar System body orbiting the Sun whose closest approach to the Sun ( perihelion) is less than 1.3 times the Earth–Sun distance (astronomical unit, AU). This definition applies to the object's orbit a ...
s (NEOs) via its NEO web form and blog, the
Near-Earth Object Confirmation Page The Near-Earth Object Confirmation Page (NEOCP) is a web service listing recently-submitted observations of objects that may be near-Earth objects (NEOs). It is a service of the Minor Planet Center (MPC), which is the official international archive ...
. 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 ''(see
Potentially hazardous object A potentially hazardous object (PHO) is a near-Earth object – either an asteroid or a comet – with an orbit that can make close approaches to the Earth and which is large enough to cause significant regional damage in the event of impact. Th ...
s and )''.


History

The Minor Planet Center was set up at the
University of Cincinnati The University of Cincinnati (UC or Cincinnati, informally Cincy) is a public university, public research university in Cincinnati, Ohio, United States. It was founded in 1819 and had an enrollment of over 53,000 students in 2024, making it the ...
in 1947, under the direction of
Paul Herget Paul Herget (January 30, 1908 – August 27, 1981) was an American astronomer and director of the Cincinnati Observatory, who established the Minor Planet Center after World War II. Career Herget taught astronomy at the University of Cincinna ...
. Upon Herget's retirement on June 30, 1978, the MPC was moved to the Smithsonian Astrophysical Observatory, under the direction of
Brian G. Marsden Brian Geoffrey Marsden (5 August 1937 – 18 November 2010) was a British astronomer and the longtime director of the Minor Planet Center (MPC) at the Center for Astrophysics Harvard & Smithsonian (director emeritus from 2006 to 2010). ...
. From 2006 to 2015, the director of the MPC was
Timothy Spahr Timothy Bruce Spahr (born 1970) is an American astronomer and prolific discoverer of minor planets. From 2000–2014 he worked at the Center for Astrophysics Harvard & Smithsonian Minor Planet Center. From September 2006 to December 2014 he wa ...
, who oversaw a staff of five. From 2015 to 2021, the Minor Planet Center was headed by interim director
Matthew Holman Matthew J. Holman (born 1967) is a Smithsonian astrophysicist and lecturer at Harvard University. Holman studied at MIT, where he received his bachelor's degree in mathematics in 1989 and his PhD in planetary science in 1994. He was awarded the ...
. Under his leadership, the MPC experienced a significant period of reorganization and growth, doubling both its staff size and the volume of observations processed per year. Upon Holman's resignation on February 9, 2021 (announced on February 19, 2021) Matthew Payne became acting director of the MPC.


Directors

* 1947–1978:
Paul Herget Paul Herget (January 30, 1908 – August 27, 1981) was an American astronomer and director of the Cincinnati Observatory, who established the Minor Planet Center after World War II. Career Herget taught astronomy at the University of Cincinna ...
* 1978–2006: Brian Marsden * 2006–2015:
Timothy Spahr Timothy Bruce Spahr (born 1970) is an American astronomer and prolific discoverer of minor planets. From 2000–2014 he worked at the Center for Astrophysics Harvard & Smithsonian Minor Planet Center. From September 2006 to December 2014 he wa ...
* 2015–2021:
Matthew Holman Matthew J. Holman (born 1967) is a Smithsonian astrophysicist and lecturer at Harvard University. Holman studied at MIT, where he received his bachelor's degree in mathematics in 1989 and his PhD in planetary science in 1994. He was awarded the ...
* 2021–present: Matthew Payne


Periodical publications

The MPC periodically releases
astrometric Astrometry is a branch of astronomy that involves precise measurements of the positions and movements of stars and other celestial bodies. It provides the kinematics and physical origin of the Solar System and this galaxy, the Milky Way. History ...
observations of minor planets, as well as of
comet A comet is an icy, small Solar System body that warms and begins to release gases when passing close to the Sun, a process called outgassing. This produces an extended, gravitationally unbound atmosphere or Coma (cometary), coma surrounding ...
s and
natural satellite A natural satellite is, in the most common usage, an astronomical body that orbits a planet, dwarf planet, or small Solar System body (or sometimes another natural satellite). Natural satellites are colloquially referred to as moons, a deriv ...
s. These publications are the Minor Planet Circulars (MPCs), the Minor Planet Electronic Circulars (MPECs), and the Minor Planet Supplements (MPSs and MPOs). 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 1979 (MPC 4937–5016). * ''Minor Planet Circulars'' (''M.P.C.'' or ''MPCs''), established 1947, is a
scientific journal In academic publishing, a scientific journal is a periodical publication designed to further the progress of science by disseminating new research findings to the scientific community. These journals serve as a platform for researchers, schola ...
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 (the full observations now being given in the ''Minor Planet Circulars'' Supplement). New numberings and namings of minor planets ''(also see
Naming of Minor Planets In ancient times, only the Sun and Moon, a few stars, and the most easily visible planets had names. Over the last few hundred years, the number of identified astronomical objects has risen from hundreds to over a billion, and more are discovered e ...
)'', 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 ''(see below)''. * The ''Minor Planet Electronic Circulars'' (''MPECs'') are published by the Minor Planet Center. They generally contain positional observations and
orbits In celestial mechanics, an orbit (also known as orbital revolution) is the curved trajectory of an physical body, object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an satellite, artificia ...
of
unusual minor planet In planetary science, the term unusual minor planet, or ''unusual object'', is used for a minor planet that possesses an unusual physical or orbital characteristic. For the Minor Planet Center (MPC), which operates under the auspices of the Internat ...
s and all
comet A comet is an icy, small Solar System body that warms and begins to release gases when passing close to the Sun, a process called outgassing. This produces an extended, gravitationally unbound atmosphere or Coma (cometary), coma surrounding ...
s. 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'' (''MPS'') is published on behalf of
IAU The International Astronomical Union (IAU; , UAI) is an international non-governmental organization (INGO) with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and developmen ...
's Division F (Planetary Systems and Bioastronomy) by the Minor Planet Center. * The ''Minor Planets and Comets Orbit Supplement'' (''MPO'') is published on behalf of IAU's Division F by the Minor Planet Center.


Natural Satellites Ephemeris Service

The Natural Satellites Ephemeris Service is an online service of the Minor Planet Center. The service provides "ephemerides, orbital elements and residual blocks for the outer irregular satellites of the giant planets


See also

*
Central Bureau for Astronomical Telegrams The Central Bureau for Astronomical Telegrams (CBAT) is an official international clearing house for information relating to transient astronomical events. The CBAT collects and distributes information on comets, natural satellites, novae, mete ...
*
IAU Circular The International Astronomical Union Circulars (IAUCs) are notices that give information about astronomical phenomena. IAUCs are issued by the International Astronomical Union's Central Bureau for Astronomical Telegrams (CBAT) at irregular interva ...
*
List of astronomical societies A list of notable groups devoted to promoting astronomy research and education. International * Astronomers for Planet Earth (A4E) * Astronomers Without Borders (AWB) *International Astronomical Union (IAU) *International Meteor Organization * Ne ...
*
List of minor-planet groups A minor-planet group is a population of minor planets that share broadly similar orbits. Members are generally unrelated to each other, unlike in an asteroid family, which often results from the break-up of a single asteroid. It is customary to na ...
*
List of minor planets The following is a list of minor planets in ascending numerical order. Minor planets are Small Solar System bodies, small bodies in the Solar System: asteroids, Distant minor planet, distant objects, and dwarf planets, but not comets. As of 2022 ...
* *
Meanings of minor-planet names This is a list of minor planets which have been officially named by the Working Group for Small Bodies Nomenclature (WGSBN) of the International Astronomical Union (IAU). The list consists of partial pages, each covering a number range of 1,000 bo ...


References


External links

*
MPC/MPO/MPS Archive
all published circulars since 1977 (downloadable as PDF)


The Minor Planet Center Status Report
Matthew J. Holman Matthew J. Holman (born 1967) is a Smithsonian astrophysicist and lecturer at Harvard University. Holman studied at MIT, where he received his bachelor's degree in mathematics in 1989 and his PhD in planetary science in 1994. He was awarded the ...
, ''8 November 2015''
Recent MPECs
list of most-recently published ''Minor Planet Electronic Circulars''


Videos

* * * {{Authority control Astronomy data and publications Astronomy magazines Astronomy organizations Science and technology magazines published in the United States Magazines established in 1947