1389 Onnie, provisional designation , is a stony Koronian

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 outer region of the asteroid belt, approximately 13 kilometers in diameter. It was discovered on 28 September 1935, by Dutch astronomer

Hendrik van Gent Hendrik van Gent (14 September 1899, Pernis – March 29, 1947, Amsterdam)''Album studiosorum Academiæ lugduno-batavæ MDCCCLXXV-MCMXXV'', A. W. Sijthoff, 1925, p. 376 was a Dutch astronomer. He moved to South Africa in 1928 in order to o ...

at Leiden Southern Station, annex to the Johannesburg Observatory in South Africa.

Orbit and classification

The stony S-type asteroid belongs to the

Koronis family ] The Koronis or Koronian family (), also known as the Lacrimosa family, is a very large asteroid family of S-type asteroid, stony asteroids, located in the Kirkwood gap, outer region of the asteroid belt. They are thought to have been formed at le ...

, a group consisting of few hundred known bodies with nearly ecliptic, ecliptical orbits. ''Onnie'' orbits the Sun at a distance of 2.8–2.9 AU once every 4 years and 10 months (1,771 days). Its orbit has an eccentricity of 0.02 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 2 ° with respect to the ecliptic. As no precoveries were taken, and no prior identifications were made, 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 official discovery observation at Johannesburg.

Lightcurve

American astronomer

Richard P. Binzel Richard "Rick" P. Binzel (born 1958) is an American astronomer and professor of planetary sciences at the Massachusetts Institute of Technology (MIT). He is a discoverer of minor planets, photometrist and the inventor of the Torino Scale, a metho ...

obtained a rotational light-curve of ''Onnie'' from photometric observations in September 1983. It gave a longer-than average

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 22.5 hours with a change in brightness of 0.34 magnitude (). In 2011 and 2013, respectively, a modeled light-curve using data from the Uppsala Asteroid Photometric Catalogue and other sources gave a period 23.0447 hours, as well as a spin axis of (183.0°, -75.0°) in ecliptic coordinates ().

Diameter and albedo

According to the 2014-published result 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, ...

with its subsequent NEOWISE mission, ''Onnie'' measures 13.77 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 0.198. The ''Collaborative Asteroid Lightcurve Link'' assumes a standard albedo for stony Koronian asteroids of 0.24 and derives a diameter of 12.46 kilometers based on an absolute magnitude of 11.69.

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 for A. Kruyt, sister-in-law of astronomer G. Pels (1893–1966). Pels, who proposed the minor planet's name, was as a lifelong member of the Leiden Observatory's staff, observer of minor planets at Leiden, as well as an orbit computer for many of Hendrik van Gent's made discoveries. The minor planet

1667 Pels Events January–March * January 11 – Aurangzeb, monarch of the Mughal Empire, orders the removal of Rao Karan Singh as Maharaja of the Bikaner State (part of the modern-day Rajasthan state of India) because of Karan's dereli ...

was named in his honour.

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:Onnie 001389 Discoveries by Hendrik van Gent Named minor planets 19350928