1995 Hajek, provisional designation , is a metallic

asteroid An asteroid is a minor planet of the inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; they are rocky, metallic or icy bodies with no atmosphere. ...

from the middle region of the asteroid belt, approximately 13 kilometers in diameter. It was discovered on 26 October 1971, by Czech astronomer Luboš Kohoutek at the

Bergedorf Observatory Hamburg Observatory (german: Hamburger Sternwarte) is an astronomical observatory located in the Bergedorf borough of the city of Hamburg in northern Germany. It is owned and operated by the University of Hamburg, Germany since 1968, although it ...

in Hamburg, Germany. It was named after Renaissance astronomer

Tadeáš Hájek Tadeáš Hájek z Hájku () (1 December 1525 in Prague – 1 September 1600 in Prague), also known as Tadeáš Hájek of Hájek, Thaddaeus Hagecius ab Hayek or Thaddeus Nemicus, was a Czech naturalist, personal physician of the Holy Roman ...

Orbit and classification

''Hajek'' orbits the Sun in the middle main-belt at a distance of 2.4–2.7 AU once every 4.02 years (1,469 days). Its orbit has an eccentricity of 0.05 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 Plane of reference, reference plane and the orbital plane or Axis of rotation, axis of direction of the orbiting object ...

of 11 ° with respect to the ecliptic. It was first identified as at Heidelberg in 1941. The body's used observation was a

precovery In astronomy, precovery (short for pre-discovery recovery) is the process of finding the image of an object in images or photographic plates predating its discovery, typically for the purpose of calculating a more accurate orbit. This happens mos ...

taken at

Palomar Observatory Palomar Observatory is an astronomical research observatory in San Diego County, California, United States, in the Palomar Mountain Range. It is owned and operated by the California Institute of Technology (Caltech). Research time at the observat ...

in 1951, extending its

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 ...

by 20 years prior to the official discovery observation at Heidelberg.

Physical characteristics

A first rotational lightcurve of ''Hajek'' was obtained by French amateur astronomers Alain Klotz, Marc Rieugné, and Pierre Thierry in October 2013. It gave a provisional

rotation period The rotation period of a celestial object (e.g., star, gas giant, planet, moon, asteroid) may refer to its sidereal rotation period, i.e. the time that the object takes to complete a single revolution around its axis of rotation relative to the ...

of 10 hours with a brightness variation of 0.10 magnitude (). ''Hajek'' has the

spectral properties In linear algebra, an eigenvector () or characteristic vector of a linear transformation is a nonzero vector that changes at most by a scalar factor when that linear transformation is applied to it. The corresponding eigenvalue, often denoted ...

of a metallic X-type asteroid. It is also classified as a dark

P-type asteroid P-type asteroids are asteroids that have low albedo and a featureless reddish spectrum. It has been suggested that they have a composition of organic rich silicates, carbon and anhydrous silicates, possibly with water ice in their interior. P-type ...

by NASA's

Wide-field Infrared Survey Explorer Wide-field Infrared Survey Explorer (WISE, observatory code C51, Explorer 92 and SMEX-6) is a NASA infrared astronomy space telescope in the Explorers Program. It was launched in December 2009, and placed in hibernation mode in February 2011, ...

(WISE). According to the surveys carried out by the Japanese Akari satellite and WISE space-telescope with its subsequent NEOWISE mission, ''Hajek'' measures between 12.7 and 15.3 kilometers in diameter and its surface has an

albedo Albedo (; ) is the measure of the diffuse reflection of sunlight, solar radiation out of the total solar radiation and measured on a scale from 0, corresponding to a black body that absorbs all incident radiation, to 1, corresponding to a body ...

of 0.040 and 0.083. The ''Collaborative Asteroid Lightcurve Link'' strongly disagrees with the space-based observations and assumes a standard albedo for stony asteroids of 0.200 and calculates a much smaller diameter of 6.5 kilometers. These contrasting albedo and diameter figures closely correspond to a generic magnitude-to-diameter conversion, where, for an absolute magnitude of 13.3, the body's diameter is in the range of 6 to 14 kilometers, based on an albedo between 0.05 and 0.25.

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 the Bohemian astronomer

(1525–1600), better known by his Latinized name, Thaddaeus Hagecius. He was one of the founders of modern stellar and cometary astronomy, who studied the

Great Comet of 1577 The Great Comet of 1577 (official designation: C/1577 V1) is a non-periodic comet that passed close to Earth during the year 1577 AD. Having an official designation beginning with "C" classes it as a non-periodic comet, and so it is not expected t ...

and the supernova SN 1572, also known as ''Tycho's Nova''. The lunar crater '' Hagecius'' is also named in his honour. 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. Function ...

on 1 April 1978 ().

References

External links

Asteroid Lightcurve Database (LCDB)
query form

)
Dictionary of Minor Planet Names
Google books

– Observatoire de Genève, Raoul Behrend

– Minor Planet Center * * {{DEFAULTSORT:Hajek 001995 Discoveries by Luboš Kohoutek Named minor planets 001995 19711026