2122 Pyatiletka, provisional designation 1971 XB, is a stony asteroid from the inner regions of the asteroid belt, approximately 11 kilometers in diameter.
The asteroid was discovered on 14 December 1971, by Soviet astronomer
Tamara Smirnova at the Crimean Astrophysical Observatory in Nauchnyj, on the Crimean peninsula. It was named for "pyatiletka", the first  Five-Year Plan of the USSR.
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.
It was first identified as
1950 BE at 1 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.
Pyatiletka has been characterized as a stony S-type asteroid.
A fragmentary rotational
lightcurve of Pyatiletka was obtained from photometric observations at the Palomar Transient Factory in California on February 2010. Lightcurve analysis gave a tentative rotation period of 8.899 hours with a brightness variation of 0.10 magnitude ( ). U=1 As of 2017, no other lightcurve has been published. 
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.   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.
minor planet was named in honor of the Five-Year Plans for the National Economy of the Soviet Union on the occasion of the 50th anniversary of its first adoption. The official naming citation was published by the  Minor Planet Center on 1 April 1980 ( ). M.P.C. 5283
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"JPL Small-Body Database Browser: 2122 Pyatiletka (1971 XB)" (2017-04-30 last obs.). Jet Propulsion Laboratory . Retrieved . 11 June 2017
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Schmadel, Lutz D. (2007). "(2122) Pyatiletka". Dictionary of Minor Planet Names – (2122) Pyatiletka. Springer Berlin Heidelberg. p. 172. doi: 10.1007/978-3-540-29925-7_2123. ISBN . 978-3-540-00238-3
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"LCDB Data for (2122) Pyatiletka". Asteroid Lightcurve Database (LCDB) . Retrieved . 27 March 2017
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Usui, Fumihiko; Kuroda, Daisuke; Müller, Thomas G.; Hasegawa, Sunao; Ishiguro, Masateru; Ootsubo, Takafumi; et al. (October 2011). "Asteroid Catalog Using Akari: AKARI/IRC Mid-Infrared Asteroid Survey". Publications of the Astronomical Society of Japan. 63 (5): 1117–1138. Bibcode: 2011PASJ...63.1117U. doi: 10.1093/pasj/63.5.1117 . Retrieved . 17 October 2019 ( online, AcuA catalog p. 153)
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Masiero, Joseph R.; Grav, T.; Mainzer, A. K.; Nugent, C. R.; Bauer, J. M.; Stevenson, R.; et al. (August 2014). "Main-belt Asteroids with WISE/NEOWISE: Near-infrared Albedos". The Astrophysical Journal. 791 (2): 11. arXiv: . 1406.6645 Bibcode: 2014ApJ...791..121M. doi: 10.1088/0004-637X/791/2/121 . Retrieved . 27 March 2017
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Mainzer, A.; Grav, T.; Masiero, J.; Hand, E.; Bauer, J.; Tholen, D.; et al. (November 2011). "NEOWISE Studies of Spectrophotometrically Classified Asteroids: Preliminary Results". The Astrophysical Journal. 741 (2): 25. arXiv: . 1109.6407 Bibcode: 2011ApJ...741...90M. doi: 10.1088/0004-637X/741/2/90.
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Waszczak, Adam; Chang, Chan-Kao; Ofek, Eran O.; Laher, Russ; Masci, Frank; Levitan, David; et al. (September 2015). "Asteroid Light Curves from the Palomar Transient Factory Survey: Rotation Periods and Phase Functions from Sparse Photometry". The Astronomical Journal. 150 (3): 35. arXiv: . 1504.04041 Bibcode: 2015AJ....150...75W. doi: 10.1088/0004-6256/150/3/75 . Retrieved . 27 March 2017
Veres, Peter; Jedicke, Robert; Fitzsimmons, Alan; Denneau, Larry; Granvik, Mikael; Bolin, Bryce; et al. (November 2015). "Absolute magnitudes and slope parameters for 250,000 asteroids observed by Pan-STARRS PS1 - Preliminary results". Icarus. 261: 34–47. arXiv: . 1506.00762 Bibcode: 2015Icar..261...34V. doi: 10.1016/j.icarus.2015.08.007 . Retrieved . 27 March 2017
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"2122 Pyatiletka (1971 XB)". Minor Planet Center . Retrieved . 27 March 2017
"MPC/MPO/MPS Archive". Minor Planet Center . Retrieved . 27 March 2017