255 Oppavia

255 Oppavia is a sizeable Main belt asteroid. It was discovered by Austrian astronomer Johann Palisa on 31 March 1886 in Vienna and was named after Opava, a town in the Czech Republic, then part of Austria-Hungary, where Palisa was born.^[3] It is orbiting the Sun at a distance of 2.75 AU with an orbital eccentricity (ovalness) of 0.077 and a period of 4.55 yr. The orbital plane is inclined by an angle of 9.47° to the plane of the ecliptic.^[1]

255 Oppavia

Discovery
Discovered by	Johann Palisa
Discovery date	31 March 1886
Designations
MPC designation	(255) Oppavia
Pronunciation	/ɒˈpeɪviə/
Named after	Opava
Alternative designations	A886 FB, 1904 EC 1924 TA, 1938 VC 1938 XC, 1945 GD 1951 SG
Minor planet category	Main belt
Orbital characteristics[1]
Epoch 31 July 2016 (JD 2457600.5)
Uncertainty parameter 0
Observation arc	129.86 yr (47,431 d)
Aphelion	2.959 AU (442.6 Gm)
Perihelion	2.533 AU (379.0 Gm)
Semi-major axis	2.746 AU (410.8 Gm)
Eccentricity	0.077427
Orbital period (sidereal)	4.551 yr (1,662.1 d)
Average orbital speed	17.98 km/s
Mean anomaly	261.139°
Mean motion	0° 12m 59.735s / day
Inclination	9.47209°
Longitude of ascending node	13.6708°
Argument of perihelion	156.011°
Physical characteristics
Dimensions	57.40±1.5 km
Synodic rotation period	19.499 h (0.8125 d)
Geometric albedo	0.0374±0.002
Spectral type	X[2]
Absolute magnitude (H)	10.39

Photometric observations made during 2013 indicate a synodic rotation period of 19.499±0.001 h with an amplitude of 0.16±0.02 in magnitude. The unusual light curve shows three uneven minima and maxima per cycle.^[4] In 1995, 255 Oppavia was suggested as a peripheral member of the now defunct Ceres asteroid family,^[5] but was found to be an unrelated interloper on the basis of its non-matching spectral type. It classified as a dark X-type asteroid in the Tholen taxonomy.^[2]