129 Antigone

129 Antigone is a large main-belt asteroid. Radar observations indicate that it is composed of almost pure nickel-iron. It and other similar asteroids probably originate from the core of a shattered Vesta-like planetesimal which had a differentiated interior. It was discovered by German-American astronomer C. H. F. Peters on February 5, 1873, and named after Antigone, the Theban princess in Greek mythology.

129 Antigone

A three-dimensional model of 129 Antigone based on its light curve.
Discovery
Discovered by	Christian Heinrich Friedrich Peters
Discovery date	5 February 1873
Designations
MPC designation	(129) Antigone
Pronunciation	/ænˈtɪɡəniː/[1]
Named after	Antigone
Alternative designations	A873 CA; 1878 CA; 1907 BA
Minor planet category	Main belt
Orbital characteristics[2]
Epoch 31 July 2016 (JD 2457600.5)
Uncertainty parameter 0
Observation arc	112.47 yr (41080 d)
Aphelion	3.4773 AU (520.20 Gm)
Perihelion	2.26344 AU (338.606 Gm)
Semi-major axis	2.87038 AU (429.403 Gm)
Eccentricity	0.21145
Orbital period (sidereal)	4.86 yr (1776.3 d)
Average orbital speed	17.39 km/s
Mean anomaly	97.3536°
Mean motion	0° 12m 9.619s / day
Inclination	12.262°
Longitude of ascending node	135.703°
Argument of perihelion	111.076°
Earth MOID	1.2837 AU (192.04 Gm)
Jupiter MOID	1.7487 AU (261.60 Gm)
TJupiter	3.232
Physical characteristics
Dimensions	113[2] 119.44 ± 3.91 km[3]
Mass	(2.65 ± 0.89) × 1018 kg[3]
Mean density	2.96 ± 1.04 g/cm3[3]
Equatorial surface gravity	0.0349 m/s2
Equatorial escape velocity	0.0661 km/s
Synodic rotation period	4.9572 h (0.20655 d)[2][4]
Geometric albedo	0.164
Temperature	~164 K
Spectral type	M
Apparent magnitude	9.71 (brightest?)
Absolute magnitude (H)	7.07

In 1979 a possible satellite of Antigone was suggested based on lightcurve data.^[5] A model constructed from these shows Antigone itself to be quite regularly shaped. In 1990, the asteroid was observed from the Collurania-Teramo Observatory, allowing a composite light curve to be produced that showed a rotation period of 4.9572 ± 0.0001 hours and a brightness variation of 0.34 ± 0.01 in magnitude. The ratio of the lengths of the major to minor axes for this asteroid were found to be 1.45 ±0.02.^[4]

10μ radiometric data collected from Kitt Peak in 1975 gave a diameter estimate of 114 km.^[6] Since 1985, a total of three stellar occultations by Antigone have been observed. A favorable occultation of a star on April 11, 1985, was observed from sites near Pueblo, Colorado, allowing a diameter estimate of 113.0 ± 4.2 km to be calculated.^[7]