2122 Pyatiletka

2122 Pyatiletka, provisional designation 1971 XB, is a stony asteroid from the inner regions of the asteroid belt, approximately 11 kilometers in diameter.

2122 Pyatiletka

Discovery[1]
Discovered by	T. Smirnova
Discovery site	Crimean Astrophysical Obs.
Discovery date	14 December 1971
Designations
MPC designation	(2122) Pyatiletka
Named after	Pyatiletka (Five-year plans of the USSR)[2]
Alternative designations	1971 XB · 1950 BE1 1950 DX · 1951 KB1 1954 DA · 1961 AL 1969 EV1
Minor planet category	main-belt · (inner)[3]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc	63.18 yr (23,075 days)
Aphelion	2.4729 AU
Perihelion	2.3310 AU
Semi-major axis	2.4019 AU
Eccentricity	0.0295
Orbital period (sidereal)	3.72 yr (1,360 days)
Mean anomaly	197.74°
Mean motion	0° 15m 53.28s / day
Inclination	7.8981°
Longitude of ascending node	105.50°
Argument of perihelion	236.47°
Physical characteristics
Dimensions	10.75 km (calculated)[3] 11.00±0.83 km[4] 11.084±0.101 km[5] 11.554±0.074 km[6]
Synodic rotation period	8.899±0.0053 h[7]
Geometric albedo	0.1931±0.0198[6] 0.20 (assumed)[3] 0.211±0.033[4] 0.224±0.023[5]
Spectral type	S[3]
Absolute magnitude (H)	11.759±0.002 (R)[7] · 12.1[1][4][6] · 12.21[3] · 12.40±0.29[8]

The asteroid was discovered on 14 December 1971 by Soviet astronomer Tamara Smirnova at the Crimean Astrophysical Observatory in Nauchnyj, on the Crimean peninsula.^[9] It was named for "pyatiletka", the first Five-Year Plan of the USSR.^[2]

Orbit and classification

Pyatiletka orbits the Sun in the inner main-belt at a distance of 2.3–2.5 AU once every 3 years and 9 months (1,360 days). Its orbit has an eccentricity of 0.03 and an inclination of 8° with respect to the ecliptic.^[1]

It was first identified as 1950 BE₁ at Simeiz Observatory in 1950. The body's observation arc begins at Lowell Observatory in 1961, when it was identified as 1961 AL, 10 years prior to its official discovery observation at Nauchnyj.^[9]

Physical characteristics

Pyatiletka has been characterized as a stony S-type asteroid.^[3]

Lightcurves

A fragmentary rotational lightcurve of Pyatiletka was obtained from photometric observations at the Palomar Transient Factory in California in February 2010. Lightcurve analysis gave a tentative rotation period of 8.899 hours with a brightness variation of 0.10 magnitude (U=1).^[7] As of 2017, no other lightcurve has been published.^[3]

Diameter and albedo

According to the surveys carried out by the Japanese Akari satellite and NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Pyatiletka measures between 11.00 and 11.55 kilometers in diameter, and its surface has an albedo between 0.1931 and 0.224.^[4][5][6] The Collaborative Asteroid Lightcurve Link assumes a standard albedo for stony asteroids of 0.20 and calculates a diameter of 10.75 kilometers with an absolute magnitude of 12.21.^[3]

Naming

This minor planet was named in honor of the five-year plans of the Soviet Union on the occasion of the 50th anniversary of its first adoption.^[2] The official naming citation was published by the Minor Planet Center on 1 April 1980 (M.P.C. 5283).^[10]