1161 Thessalia

1161 Thessalia, provisional designation 1929 SF, is a dark background asteroid from the outer regions of the asteroid belt, approximately 21 kilometers in diameter. It was discovered on 29 September 1929, by German astronomer Karl Reinmuth at the Heidelberg-Königstuhl State Observatory.^[7] It was named for the Greek region Thessaly.^[3]

1161 Thessalia

Discovery[1]
Discovered by	K. Reinmuth
Discovery site	Heidelberg Obs.
Discovery date	29 September 1929
Designations
MPC designation	(1161) Thessalia
Pronunciation	/θɪˈseɪliə/[2]
Named after	Thessaly (Greek region)[3]
Alternative designations	1929 SF · 1931 BB
Minor planet category	main-belt · (outer) background[4]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc	87.76 yr (32,056 days)
Aphelion	3.4488 AU
Perihelion	2.8975 AU
Semi-major axis	3.1732 AU
Eccentricity	0.0869
Orbital period (sidereal)	5.65 yr (2,065 days)
Mean anomaly	213.02°
Mean motion	0° 10m 27.84s / day
Inclination	9.3913°
Longitude of ascending node	72.567°
Argument of perihelion	309.20°
Physical characteristics
Dimensions	21.498±0.184 km[5]
Geometric albedo	0.065±0.010[6]
Absolute magnitude (H)	11.2[1]

Orbit and classification

Thessalia is a non-family asteroid from the main belt's background population.^[4] It orbits the Sun in the outer main-belt at a distance of 2.9–3.4 AU once every 5 years and 8 months (2,065 days). Its orbit has an eccentricity of 0.09 and an inclination of 9° with respect to the ecliptic.^[1] The body's observation arc begins at Heidelberg, five weeks after its official discovery observation.^[7]

Physical characteristics

Diameter and albedo

According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Thessalia measures 21.498 kilometers in diameter and its surface has an albedo of 0.065.^[5][6]

Lightcurves

As of 2017, no rotational lightcurve of Thessalia has been obtained from photometric observations. The asteroid's rotation period, poles and shape remain unknown.^[8]

Naming

This minor planet was named for the Thessaly region in eastern Greece. The subsequently numbered minor planet 1162 Larissa was named after the region's capital. The official naming citation was mentioned in The Names of the Minor Planets by Paul Herget in 1955 (H 108).^[3]