9903 Leonhardt

9903 Leonhardt, provisional designation 1997 NA₁, is a dark asteroid from the outer region of the asteroid belt, approximately 10 kilometers in diameter.

9903 Leonhardt

Orbit of Leonhardt (blue), with the inner planets and Jupiter (outermost)
Discovery[1]
Discovered by	P. G. Comba
Discovery site	Prescott Obs.
Discovery date	4 July 1997
Designations
MPC designation	(9903) Leonhardt
Named after	Gustav Leonhardt (conductor and harpsichordist)[2]
Alternative designations	1997 NA1 · 1976 UG6
Minor planet category	main-belt[1][3] · (outer)
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc	40.43 yr (14,767 days)
Aphelion	3.8232 AU
Perihelion	2.3527 AU
Semi-major axis	3.0880 AU
Eccentricity	0.2381
Orbital period (sidereal)	5.43 yr (1,982 days)
Mean anomaly	240.21°
Mean motion	0° 10m 53.76s / day
Inclination	1.6903°
Longitude of ascending node	195.95°
Argument of perihelion	139.13°
Physical characteristics
Dimensions	8.499±0.240 km[4] 17.8 km[5]
Geometric albedo	0.042±0.008[4]
Absolute magnitude (H)	14.5[1]

The asteroid was discovered on 4 July 1997, by American amateur astronomer Paul Comba at Prescott Observatory in Arizona, United States.^[3] It was named after Dutch keyboard player Gustav Leonhardt.^[2]

Orbit and classification

Leonhardt orbits the Sun in the outer main-belt at a distance of 2.4–3.8 AU once every 5 years and 5 months (1,982 days). Its orbit has an eccentricity of 0.24 and an inclination of 2° with respect to the ecliptic.^[1]

It was first identified as 1976 UG₆ at Kiso Observatory in 1976, extending the body's observation arc by 21 years prior to its official discovery observation at Prescott.^[3]

Physical characteristics

Diameter and albedo

According to the surveys carried out by the Infrared Astronomical Satellite IRAS and NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Leonhardt measures 17.8 and 8.499 kilometers in diameter, respectively.^[4][5] WISE/NEOWISE also gives an albedo of 0.042 for the body's surface.^[4] It has an absolute magnitude of 14.5.^[1]

Lightcurves

As of 2017, the asteroid's rotation period and shape remain unknown.^[1][6]

Naming

This minor planet was named for Gustav Leonhardt (1928–2012), a Dutch conductor and harpsichordist, who founded the Leonhardt Baroque Ensemble. He was known for his many international concert tours and for his large number of recorded baroque works.^[2] The official naming citation was published by the Minor Planet Center on 2 April 1999 (M.P.C. 34356).^[7]

The main-belt asteroid 12637 Gustavleonhardt, discovered during the second Palomar–Leiden Trojan survey campaign in 1973, is also named in his honor.^[8]