230 Athamantis

230 Athamantis is a fairly large main-belt asteroid that was discovered by the German-Austrian astronomer K. de Ball on September 3, 1882, in Bothkamp. It was his only asteroid discovery. The asteroid was named after Athamantis, daughter of Athamas the mythical Greek king of Orchomenus.

230 Athamantis

Discovery
Discovered by	K. de Ball
Discovery date	3 September 1882
Designations
MPC designation	(230) Athamantis
Pronunciation	/æθəˈmæntɪs/
Named after	Helle
Alternative designations	1949 WG
Minor planet category	Main belt
Orbital characteristics[1]
Epoch 31 July 2016 (JD 2457600.5)
Uncertainty parameter 0
Observation arc	133.58 yr (48791 d)
Aphelion	2.52818 AU (378.210 Gm)
Perihelion	2.23641 AU (334.562 Gm)
Semi-major axis	2.38229 AU (356.386 Gm)
Eccentricity	0.06124
Orbital period (sidereal)	3.68 yr (1343.0 d)
Average orbital speed	19.3 km/s
Mean anomaly	116.2°
Mean motion	0° 16m 4.969s / day
Inclination	9.443°
Longitude of ascending node	239.9°
Argument of perihelion	139.1°
Physical characteristics
Mean diameter	118±2 km[2] 111.332±1.231 km[1] 110.17 ± 4.57 km[3]
Flattening	0.24[a]
Mass	(2.3±1.1)×1018 kg[2] (1.89±0.19)×1018 kg[3]
Mean density	2.7±1.3 g/cm3[2] 2.69±0.43 g/cm3[3]
Synodic rotation period	24.0055 h (1.00023 d)[1] 23.99 h[4]
Geometric albedo	0.146 (calculated)[2] 0.164±0.029[1]
Spectral type	S
Absolute magnitude (H)	7.53[1]

Photometric observations of this asteroid gave a light curve with a period of 23.99 hours and a brightness variation of more than 0.20 in magnitude.^[4] It has the spectrum of an S-type asteroid. During 1991, the asteroid was observed occulting a star. The resulting chords provided a cross-section diameter estimate of 101.8 km.^[5]

A three-dimensional model of 230 Athamantis based on its light curve

Notes

1. Flattening derived from the maximum aspect ratio (c/a): ${\displaystyle f=1-{\frac {c}{a}}}$, where (c/a) = 0.76±0.07.^[2]