1911 Schubart

1911 Schubart, provisional designation 1973 UD, is a dark Hildian asteroid and parent body of the Schubart family, located in the outermost region of the asteroid belt, approximately 70 kilometers in diameter. It was discovered on 25 October 1973, by Swiss astronomer Paul Wild at Zimmerwald Observatory, near Bern, Switzerland.^[12] The asteroid was named after German astronomer Joachim Schubart.^[2]

1911 Schubart

Discovery[1]
Discovered by	P. Wild
Discovery site	Zimmerwald Obs.
Discovery date	25 October 1973
Designations
MPC designation	(1911) Schubart
Named after	Joachim Schubart (German astronomer)[2]
Alternative designations	1973 UD · 1928 DW 1933 UX1 · 1941 SU1 1951 AH1 · 1952 DS2 1960 EF · 1968 FM 1972 RO · 1972 TY4
Minor planet category	main-belt · (outer)[1] Hilda · Schubart[3]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc	89.27 yr (32,606 days)
Aphelion	4.6512 AU
Perihelion	3.3013 AU
Semi-major axis	3.9762 AU
Eccentricity	0.1697
Orbital period (sidereal)	7.93 yr (2,896 days)
Mean anomaly	136.84°
Mean motion	0° 7m 27.48s / day
Inclination	1.6431°
Longitude of ascending node	284.84°
Argument of perihelion	181.75°
Jupiter MOID	0.5059 AU
TJupiter	3.0310
Physical characteristics
Dimensions	64.66±23.84 km[4] 67.476±0.504 km[5] 80.09±2.0 km[6] 80.11 km (derived)[7] 80.13±1.25 km[8]
Synodic rotation period	7.91±0.02 h[9] 11.915±0.002 h[10]
Geometric albedo	0.0249±0.001[6] 0.025±0.001[8] 0.0316 (derived)[7] 0.035±0.001[5] 0.04±0.01[5] 0.04±0.03[4]
Spectral type	Tholen = P[1][7] · C/P[5] B–V = 0.701[1] U–B = 0.217[1]
Absolute magnitude (H)	9.85[7][11] · 10.11[1][4][6][8]

Orbit and classification

With a diameter of 65–80 kilometers, it is one of the largest members of the Hilda group of asteroids, which are in 3:2 orbital resonance with the gas-giant Jupiter. More specifically, it is the parent body and namesake of the Schubart family (002),^[3] one of two asteroid families within the Hilda group (the other one is the Hilda family itself).^{[13][14]: 23} It is the darkest P-type asteroid with a very low geometric albedo of 0.0249.^[1]

The body's observation arc begins with its first identification as 1928 DW at Heidelberg Observatory in February 1928, more than 45 years prior to its official discovery observation at Zimmerwald .^[12]

Physical characteristics

In the Tholen classification, Schubart is a primitive P-type asteroid.^[1][7] The Wide-field Infrared Survey Explorer (WISE) characterized it as both P- and C-type asteroid.^[5]

Diameter and albedo

According to the surveys carried out by the Infrared Astronomical Satellite IRAS, the Japanese Akari satellite and the NEOWISE mission of NASA's WISE telescope, Schubart measures between 64.66 and 80.13 kilometers in diameter and its surface has an albedo between 0.0249 and 0.04.^[4][5][6][8]

The Collaborative Asteroid Lightcurve Link derives an albedo of 0.0316 and a diameter of 80.11 kilometers based on an absolute magnitude of 9.85.^[7]

Rotation period

Two rotational lightcurves of Schubart were obtained from photometric observations by Johan Warell and Robert Stephens in 2015 and 2016, respectively. Lightcurve analysis gave a rotation period of 7.91 and 11.915 hours with a brightness amplitude of 0.11 and 0.22 in magnitude, respectively (U=2/2).^[9][10]

Naming

The minor planet is named in after German ARI-astronomer Joachim Schubart (born 1928), who is also a discoverer of minor planets, namely 2000 Herschel and 4724 Brocken. He studied in detail members of the Hilda family, as he developed an averaging techniques for observing the long-term motions of asteroids.^[2] Schubart has also been an active member on several commissions of the International Astronomical Union.^[15] The official naming citation was published by the Minor Planet Center on 20 February 1976 (M.P.C. 3937).^[16]