817 Annika

817 Annika
Discovery
Discovered by	M. F. Wolf
Discovery site	Heidelberg Obs.
Discovery date	6 February 1916
Designations
MPC designation	(817) Annika
Pronunciation	/ˈænɪkə/ German: [ˈanikaː]
Named after	a girl named "Anika"
Alternative designations	A916 · CD 1916 YW
Minor planet category	main-belt · (middle); background · Eunomia;
Orbital characteristics
	Epoch 31 May 2020 (JD 2459000.5)
	Uncertainty parameter 0
Observation arc	103.99 yr (37,982 d)
Aphelion	3.0570 AU
Perihelion	2.1231 AU
Semi-major axis	2.5900 AU
Eccentricity	0.1803
Orbital period (sidereal)	4.17 yr (1,523 d)
Mean anomaly	61.065°
Mean motion	0° 14m 11.4s / day
Inclination	11.336°
Longitude of ascending node	125.47°
Argument of perihelion	285.18°
Physical characteristics
Dimensions	22.0 km × 22.0 km
Mean diameter	22.05±1.7 km; 22.891±0.100 km; 23.02±0.34 km;
Mean density	~2.7 g/cm3 (estimate)
Synodic rotation period	10.560±0.004 h; 10.564±0.001 h;
Geometric albedo	0.163±0.006; 0.1740±0.030; 0.191±0.027;
Spectral type	S (S3OS2-TH); Sl (S3OS2-BB);
Absolute magnitude (H)	10.60; 10.80;

817 Annika (prov. designation: A916 CD or 1916 YW) is a background asteroid in the region of the Eunomia family, located in the central portion of the asteroid belt. It was discovered on 6 February 1916, by German astronomer Max Wolf at the Heidelberg-Königstuhl State Observatory in southwest Germany. The stony S-type asteroid (Sl) has a rotation period of 10.56 hours and measures approximately 23 kilometers (14 miles) in diameter .