1503 Kuopio

1503 Kuopio, provisional designation 1938 XD, is a stony Eunomian asteroid from the central region of the asteroid belt, approximately 19 kilometers in diameter. It was discovered on 15 December 1938, by astronomer Yrjö Väisälä at the Turku Observatory in Southwest Finland.^[13] The asteroid was named for the Finnish town of Kuopio.^[2]

1503 Kuopio

Lightcurve-based 3D-model of Kuopio
Discovery[1]
Discovered by	Y. Väisälä
Discovery site	Turku Obs.
Discovery date	15 December 1938
Designations
MPC designation	(1503) Kuopio
Named after	Kuopio (Finnish town)[2]
Alternative designations	1938 XD · 1935 EF 1953 LH
Minor planet category	main-belt · (middle) Eunomia[3][4]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc	82.34 yr (30,075 days)
Aphelion	2.8995 AU
Perihelion	2.3499 AU
Semi-major axis	2.6247 AU
Eccentricity	0.1047
Orbital period (sidereal)	4.25 yr (1,553 days)
Mean anomaly	154.93°
Mean motion	0° 13m 54.48s / day
Inclination	12.369°
Longitude of ascending node	316.98°
Argument of perihelion	177.92°
Physical characteristics
Dimensions	18.43±1.5 km[5] 18.54 km (derived)[3] 22.33±0.34 km[6] 22.985±0.964 km[7]
Synodic rotation period	9.577±0.0004 h[8] 9.957±0.006 h[8] 9.9586±0.0005 h[9][10] 9.96±0.05 h[8] 9.98 h[11]
Geometric albedo	0.223±0.008[6] 0.2995±0.056[5] 0.3243 (derived)[3] 0.399±0.262[7]
Spectral type	S[3]
Absolute magnitude (H)	9.81[7] · 10.5[1][3] · 10.60[5][6] · 10.65±0.69[12]

Orbit and classification

Kuopio is a member of the Eunomia family (502), a prominent family of stony S-type asteroid and the largest one in the intermediate main belt with more than 5,000 members.^{[3][4][14]: 23} It orbits the Sun at a distance of 2.3–2.9 AU once every 4 years and 3 months (1,553 days). Its orbit has an eccentricity of 0.10 and an inclination of 12° with respect to the ecliptic.^[1]

The body's observation arc begins with its first identification as 1935 EF at Yerkes Observatory in March 1935, more than 3 years prior to its official discovery observation at Turku.^[13]

Physical characteristics

Rotation period

Several rotational lightcurves of Kuopio were obtained from photometric observations since 2001. Analysis of these lightcurves gave a rotation period between 9.577 and 9.98 hours with a brightness variation of 0.01 to 0.05 magnitude (U=3/3/2/2/3).^[8][11]

Poles

In 2011 and 2013, a modeled lightcurve using data from the Uppsala Asteroid Photometric Catalogue (UAPC) and other sources was published. In both studies, the modeled lightcurve gave a concurring period 9.9586 hours. The 2013-publication also determined two spin axis of (170.0°, −86.0°) and (27.0°, −61.0°) in ecliptic coordinates (λ, β) (U=n.a.).^[9][10]

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 Wide-field Infrared Survey Explorer, Kuopio measures between 18.43 and 22.99 kilometers in diameter and its surface has an albedo between 0.223 and 0.399.^[5][6][7]

The Collaborative Asteroid Lightcurve Link derives an albedo of 0.3243 and a diameter of 18.54 kilometers based on an absolute magnitude of 10.5.^[3]

Naming

This minor planet was named after the town of Kuopio in central Finland.^[2] The official naming citation was published by the Minor Planet Center on 20 February 1976 (M.P.C. 3928).^[15]