1830 Pogson, provisional designation , is a stony Florian asteroid and an asynchronous

binary system A binary system is a system of two astronomical bodies of the same kind that are comparable in size. Definitions vary, but typically require the center of mass to be located outside of either object. (See animated examples.) The most common ki ...

from the inner regions of the

asteroid belt The asteroid belt is a torus-shaped region in the Solar System, centered on the Sun and roughly spanning the space between the orbits of the planets Jupiter and Mars. It contains a great many solid, irregularly shaped bodies called asteroids ...

, approximately in diameter. It was discovered on 17 April 1968, by Swiss astronomer Paul Wild at the

Zimmerwald Observatory The Zimmerwald Observatory () is an astronomical observatory owned and operated by the AIUB, the Astronomical Institute of the University of Bern. Built in 1956, it is located at Zimmerwald, 10 kilometers south of Bern, Switzerland. Numerous com ...

near Bern, Switzerland. The

S-type asteroid S-type (stony-type or silicaceous-type) asteroids are asteroids with a spectral type that is indicative of a siliceous (i.e. stony) mineralogical composition, hence the name. They have relatively high density. Approximately 17% of asteroids are ...

has a

rotation period In astronomy, the rotation period or spin period of a celestial object (e.g., star, planet, moon, asteroid) has two definitions. The first one corresponds to the '' sidereal rotation period'' (or ''sidereal day''), i.e., the time that the objec ...

2.6 of hours. It was named for English astronomer

Norman Pogson Norman Robert Pogson, CIE (23 March 1829 – 23 June 1891) was an English astronomer who worked in India at the Madras observatory. He discovered several minor planets and made observations on comets. He introduced a mathematical scale of stel ...

. The discovery of its 2.5-kilometer sized

companion Companion may refer to: Relationships Currently * Any of several interpersonal relationships such as friend or acquaintance * A domestic partner, akin to a spouse * Sober companion, an addiction treatment coach * Companion (caregiving), a caregive ...

was announced in May 2007.

Orbit and classification

According to a HCM-analysis by

David Nesvorný David (; , "beloved one") was a king of ancient Israel and Judah and the third king of the United Monarchy, according to the Hebrew Bible and Old Testament. The Tel Dan stele, an Aramaic-inscribed stone erected by a king of Aram-Damas ...

, ''Pogson'' is a member of the

Flora family The Flora family (''adj. Florian''; ; also known as the Ariadne family) is a prominent family of stony asteroids located in the inner region of the asteroid belt. It is one of the largest families with more than 13,000 known members, or approx ...

(), a giant

asteroid clan An asteroid family is a population of asteroids that share similar proper orbital elements, such as semimajor axis, eccentricity, and orbital inclination. The members of the families are thought to be fragments of past asteroid collisions. An ...

and the largest

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

of stony asteroids in the asteroid belt. It has also been grouped into the Augusta family () by Zappalà, while for Milani and

Knežević Knežević () is a Serbian, Croatian, Montenegrin and Bosnian surname, derived from the title of '' knez''. It may refer to: * House of Knežević, Croatian noble family Knežević is the eighth most frequent surname in Croatia. The angliciz ...

, who don't recognize the Florian clan as a family, ''Pogson'' is a non-family asteroid from the main belt's background population. It orbits the Sun in the inner asteroid belt at a distance of 2.1–2.3 AU once every 3 years and 3 months (1,182 days;

semi-major axis In geometry, the major axis of an ellipse is its longest diameter: a line segment that runs through the center and both foci, with ends at the two most widely separated points of the perimeter. The semi-major axis (major semiaxis) is the longe ...

of 2.19 AU). Its orbit has an

eccentricity Eccentricity or eccentric may refer to: * Eccentricity (behavior), odd behavior on the part of a person, as opposed to being "normal" Mathematics, science and technology Mathematics * Off-Centre (geometry), center, in geometry * Eccentricity (g ...

of 0.06 and an

inclination Orbital inclination measures the tilt of an object's orbit around a celestial body. It is expressed as the angle between a reference plane and the orbital plane or axis of direction of the orbiting object. For a satellite orbiting the Eart ...

of 4 ° with respect to the

ecliptic The ecliptic or ecliptic plane is the orbital plane of Earth's orbit, Earth around the Sun. It was a central concept in a number of ancient sciences, providing the framework for key measurements in astronomy, astrology and calendar-making. Fr ...

. The asteroid was first observed as at

Simeiz Observatory Simeiz Observatory (also spelled Simeis or Simeïs) was an astronomy research observatory until the mid-1950s. It is located on Mount Koshka, Crimea, by the town of Simeiz. Part of the Crimean Astrophysical Observatory, it is currently used fo ...

in April 1926. The body's

observation arc In observational astronomy, the observation arc (or arc length) of a Solar System body is the time period between its earliest and latest observations, used for tracing the body's path. It is usually given in days or years. The term is mostly use ...

begins with its observation as at

Heidelberg Observatory Heidelberg (; ; ) is the List of cities in Baden-Württemberg by population, fifth-largest city in the States of Germany, German state of Baden-Württemberg, and with a population of about 163,000, of which roughly a quarter consists of studen ...

in March 1929, or 39 years prior to its official discovery observation at

Zimmerwald Zimmerwald () was an independent municipality in the Canton of Bern, Switzerland until 31 December 2003. It is located on a hill in the proximity of the city of Bern in the Bernese Mittelland. On 1 January 2004 Zimmerwald united with the municipa ...

Naming

This

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 ...

was named after English astronomer

(1829–1891), inventor of the modern astronomical magnitude scale. At the Radcliffe and

Madras Chennai, also known as Madras ( its official name until 1996), is the capital and largest city of Tamil Nadu, the southernmost state of India. It is located on the Coromandel Coast of the Bay of Bengal. According to the 2011 Indian ce ...

observatories, he discovered eight asteroids, including 42 Isis and 67 Asia. The official was published by the

Minor Planet Center 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. Funct ...

on 15 October 1977 (). The lunar crater '' Pogson'' was also named in his honor.

Physical characteristics

In the

Tholen Tholen () is a 25,000 people municipality in the southwest of the Netherlands. The municipality of Tholen takes its name from the town of Tholen, which is the largest population center in the municipality. The municipality consists of two peninsu ...

and

SMASS classification An asteroid spectral type is assigned to asteroids based on their reflectance spectrum, color, and sometimes albedo. These types are thought to correspond to an asteroid's surface composition. For small bodies that are not internally different ...

, ''Pogson'' is a common, stony

Rotation period

In April 2007, a rotational

lightcurve In astronomy, a light curve is a graph (discrete mathematics), graph of the Radiance, light intensity of a celestial object or region as a function of time, typically with the magnitude (astronomy), magnitude of light received on the ''y''-axis ...

of ''Pogson'' was obtained from photometric observations by an international collaboration of Australian, European and American astronomers, namely, David Higgins ,

Petr Pravec Petr Pravec (born September 17, 1967) is a Czech astronomer and a discoverer of minor planets, born in Třinec, Czech Republic. Pravec is a prolific discoverer of binary asteroids, expert in photometric observations and rotational lightcurves ...

Peter Kušnirák Peter Kušnirák (born 1974) is a Slovak astronomer, discoverer of minor planets, and a prolific photometrist of light-curves at Ondřejov Observatory in the Czech Republic. He was married to Slovak astronomer Ulrika Babiaková with whom he dis ...

Julian Oey Julian may refer to: People * Julian (emperor) (331–363), Roman emperor from 361 to 363 * Julian, of the Roman gens Julia, with imperial dynasty offshoots * Saint Julian (disambiguation), several Christian saints * Julian (given name), people ...

and Donald Pray. Lightcurve analysis gave a

of hours with a brightness variation of 0.12

magnitude Magnitude may refer to: Mathematics *Euclidean vector, a quantity defined by both its magnitude and its direction *Magnitude (mathematics), the relative size of an object *Norm (mathematics), a term for the size or length of a vector *Order of ...

(). In the following month, a more refined period of hours with the same amplitude was measured by Petr Pravec (). Additional period determinations were made by Melissa Dykhuis and collaborators (2.5698 h) at the Calvin College Observatory during 2008 (), and by

Pierre Antonini Pierre Antonini is a retired French mathematics professor and amateur astronomer who has discovered several minor planets and two supernovae at his private Observatoire de Bédoin (Bedoin Observatory; observatory code: 132) located at Bédoin ...

(2.5699 h) and Julian Oey (2.604 h) in March 2013 ().

Satellite

During the photometric observation in 2007, it was also revealed, that ''Pogson'' is an asynchronous

with a

minor-planet moon A minor-planet moon is an astronomical object that orbits a minor planet as its natural satellite. , there are 457 minor planets known or suspected to have moons. Discoveries of minor-planet moons (and binary objects, in general) are important ...

in its orbit. The mutual eclipse and

occultation An occultation is an event that occurs when one object is hidden from the observer by another object that passes between them. The term is often used in astronomy, but can also refer to any situation in which an object in the foreground blocks f ...

events showed that the companion orbits its primary every 24.24 hours. Based on a secondary-to-primary diameter ratio of 0.32 or larger, Johnston's archive estimates a diameter of 2.52 kilometers for the satellite, separated by 8 kilometers from its primary.

Diameter and albedo

According to the survey carried out by the

NEOWISE Wide-field Infrared Survey Explorer (WISE, observatory code C51, Explorer 92 and MIDEX-6) was a NASA infrared astronomy space telescope in the Explorers Program launched in December 2009.. . WISE discovered thousands of minor planets and nu ...

mission of NASA's

Wide-field Infrared Survey Explorer Wide-field Infrared Survey Explorer (WISE, List of observatory codes, observatory code C51, Explorer 92 and MIDEX-6) was a NASA infrared astronomy Space observatory, space telescope in the Explorers Program launched in December 2009.. . WISE L ...

, ''Pogson'' measures between 7.7 and 8.35 kilometers in diameter and its surface has an

albedo Albedo ( ; ) is the fraction of sunlight that is Diffuse reflection, diffusely reflected by a body. It is measured on a scale from 0 (corresponding to a black body that absorbs all incident radiation) to 1 (corresponding to a body that reflects ...

between 0.2188 and 0.274. The ''Collaborative Asteroid Lightcurve Link'' adopts the result from Petr Pravec's revised WISE-data, that is, an albedo of 0.2188 and a diameter of 8.35 kilometers based on an absolute magnitude of 12.659.