167 Urda

167 Urda is a main-belt asteroid that was discovered by German-American astronomer Christian Heinrich Friedrich Peters on August 28, 1876, in Clinton, New York, and named after Urd, one of the Norns in Norse mythology. In 1905, Austrian astronomer Johann Palisa showed that the asteroid varied in brightness.^[2]

167 Urda

A three-dimensional model of 167 Urda based on its light curve.
Discovery
Discovered by	C. H. F. Peters
Discovery site	Clinton, New York
Discovery date	28 August 1876
Designations
MPC designation	(167) Urda
Pronunciation	/ˈɜːrdə/
Named after	Urd
Alternative designations	A876 QA; 1899 KC; 1905 QA; 1906 WA
Minor planet category	main belt (Koronis asteroid family)
Orbital characteristics[1]
Epoch 31 July 2016 (JD 2457600.5)
Uncertainty parameter 0
Observation arc	132.01 yr (48218 d)
Aphelion	2.9583526 AU (442.56325 Gm)
Perihelion	2.7493497 AU (411.29686 Gm)
Semi-major axis	2.8538511 AU (426.93005 Gm)
Eccentricity	0.0366177
Orbital period (sidereal)	4.82 yr (1760.9 d)
Mean anomaly	37.607175°
Mean motion	0° 12m 15.969s / day
Inclination	2.212408°
Longitude of ascending node	166.21859°
Argument of perihelion	133.03586°
Earth MOID	1.73392 AU (259.391 Gm)
Jupiter MOID	2.10867 AU (315.453 Gm)
TJupiter	3.302
Physical characteristics
Dimensions	39.94±1.9 km
Synodic rotation period	13.07 h (0.545 d)
Geometric albedo	0.2230±0.023
Spectral type	S
Absolute magnitude (H)	9.1

Photometric observations of this asteroid at the Palmer Divide Observatory in Colorado Springs, Colorado, during 2007–8 gave a light curve with a period of 13.06133 ± 0.00002 hours.^[3] This S-type asteroid is a member of the Koronis family of asteroids that share similar orbital elements.^[4]

In 2002, a diameter estimate of 37.93 ± 3.17 km was obtained from the Midcourse Space Experiment observations, with an albedo of 0.2523 ± 0.0448.^[5]

A stellar occultation by Urda was observed from Japan on July 23, 2001.^[6]