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7548 Engström
Discovery
Discovered by	C.-I. Lagerkvist
Discovery site	La Silla Obs.
Discovery date	16 March 1980
Designations
MPC designation	(7548) Engström
Named after	Albert Engström; (Swedish artist)
Alternative designations	1980 FW2 · 1993 QA4; 1999 TS324
Minor planet category	main-belt · Themis
Orbital characteristics
	Epoch 4 September 2017 (JD 2458000.5)
	Uncertainty parameter 0
Observation arc	36.88 yr (13,470 days)
Aphelion	3.6490 AU
Perihelion	2.6410 AU
Semi-major axis	3.1450 AU
Eccentricity	0.1603
Orbital period (sidereal)	5.58 yr (2,037 days)
Mean anomaly	151.48°
Mean motion	0° 10m 36.12s / day
Inclination	0.3170°
Longitude of ascending node	346.66°
Argument of perihelion	296.30°
Physical characteristics
Dimensions	7.70 km (calculated); 9.43±3.04 km; 11.067±0.129 km
Synodic rotation period	5.2309±0.0059 h
Geometric albedo	0.057±0.009; 0.06±0.05; 0.08 (assumed)
Spectral type	C
Absolute magnitude (H)	13.5 · 13.93 · 13.477±0.005 (R) · 13.64±0.21 · 13.75

7548 Engström, provisional designation 1980 FW₂, is dark Themistian asteroid from the outer region of the asteroid belt, approximately 9 kilometers in diameter. It was discovered on 16 March 1980, by Swedish astronomer Claes-Ingvar Lagerkvist at ESO's La Silla Observatory site in northern Chile.^[9] The asteroid was later named after Swedish artist Albert Engström.^[2]

Classification and orbit

Engström is a member of the Themis family, a dynamical family of outer-belt asteroids with nearly coplanar ecliptical orbits. It orbits the Sun at a distance of 2.6–3.6 AU once every 5 years and 7 months (2,037 days). Its orbit has an eccentricity of 0.16 and an inclination of 0° with respect to the ecliptic.^[1]

The asteroid's observation arc begins with its official discovery observation at La Silla.^[9]

Physical characteristics

Engström is an assumed carbonaceous C-type asteroid.^[3]

Rotation period

In September 2010, photometric observations by astronomers at the Palomar Transient Factory in California gave a rotational lightcurve with a period of 5.2309 hours and a brightness amplitude of 0.35 magnitude (U=2).^[7]

Diameter and albedo

According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Engström measures 9.43 and 11.1 kilometers in diameter and its surface has a low albedo of 0.057 and 0.060, respectively,^[5]^[6] while the Collaborative Asteroid Lightcurve Link (CALL) assumes an albedo of 0.08 and calculates a smaller diameter of 7.7 kilometers, based on an absolute magnitude of 13.93.^[3]

Naming

This minor planet was named after Albert Engström (1869–1940), Swedish artist and author, who became a member of the esteemed Swedish academy in 1922. He was born in Lönneberga, Småland. After his studies of Greek and Latin at Uppsala University, he went on to Valand School of Fine Arts in Gothenburg. Renowned painter of caricatures and founder of the humor magazine Strix, he is best known for his black and white illustrations.^[2] The official naming citation was published on 11 April 1998 (M.P.C. 31611).^[10]