19139 Apian

19139 Apian (provisional designation 1989 GJ₈) is a bright background asteroid from the central regions of the asteroid belt, approximately 6 kilometers in diameter. It was discovered on 6 April 1989, by German astronomer Freimut Börngen at the Karl Schwarzschild Observatory in Tautenburg, Eastern Germany. The asteroid was named for medieval German humanist Petrus Apianus.^[2][3]

19139 Apian

Discovery[1]
Discovered by	F. Börngen
Discovery site	Karl Schwarzschild Obs.
Discovery date	6 April 1989
Designations
MPC designation	(19139) Apian
Named after	Petrus Apianus[2][3] (German humanist)
Alternative designations	1989 GJ8 · 1999 XP18
Minor planet category	main-belt · (middle) background[4]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc	28.09 yr (10,261 days)
Aphelion	2.7824 AU
Perihelion	2.3841 AU
Semi-major axis	2.5832 AU
Eccentricity	0.0771
Orbital period (sidereal)	4.15 yr (1,516 days)
Mean anomaly	105.06°
Mean motion	0° 14m 14.64s / day
Inclination	8.0241°
Longitude of ascending node	48.222°
Argument of perihelion	336.68°
Physical characteristics
Dimensions	5.643±0.089 km[5]
Geometric albedo	0.265±0.039[5]
Absolute magnitude (H)	13.5[1]

Orbit and classification

Apian is a non-family asteroid from the main belt's background population.^[4] It orbits the Sun in the central asteroid belt at a distance of 2.4–2.8 AU once every 4 years and 2 months (1,516 days; semi-major axis of 2.58 AU). Its orbit has an eccentricity of 0.08 and an inclination of 8° with respect to the ecliptic.^[1]

The body's observation arc begins with a precovery published in the Digitized Sky Survey and taken at Palomar Observatory in February 1989, approximately 2 months prior to its official discovery observation at Tautenburg.^[3]

Physical characteristics

The asteroid's spectral type is unknown. Based on its albedo (see below), it is a stony rather than carbonaceous asteroid.

Rotation period

As of 2018, no rotational lightcurve of Apian has been obtained from photometric observations. The asteroid's rotation period, poles and shape remain unknown.^[1][6]

Diameter and albedo

According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Apian measures 5.643 kilometers in diameter and its surface has an albedo of 0.265.^[5]

Naming

This minor planet was named after Petrus Apianus (1495–1552), also known as Peter Apian, a German mathematician and cartographer, who also built astronomical instruments. He is best known for his sky atlas Astronomicum Caesareum published in 1540. The lunar crater Apianus was also named in his honor.^[2]

The approved naming citation was published by the Minor Planet Center on 20 November 2002 (M.P.C. 47168).^[7]