{{Short description|Stony asteroid}} {{Use dmy dates|date=October 2019}} {{Infobox planet | minorplanet = yes | name = 2122 Pyatiletka | background = #D6D6D6 | image = | image_size = | caption = | discovery_ref = <ref name="jpldata" /> | discovered = 14 December 1971 | discoverer = T. Smirnova | discovery_site = {{nowrap|Crimean Astrophysical Obs.}} | mpc_name = (2122) Pyatiletka | alt_names = 1971 XB{{·}}{{mp|1950 BE|1}}<br />1950 DX{{·}}{{mp|1951 KB|1}}<br />1954 DA{{·}}1961 AL<br />{{mp|1969 EV|1}} | pronounced = | named_after = Pyatiletka<br />{{small|(Five-year plans of the USSR)}}<ref name="springer" /> | mp_category = main-belt{{·}}{{small|(inner)}}<ref name="lcdb" /> | orbit_ref = <ref name="jpldata" /> | epoch = 4 September 2017 (JD 2458000.5) | uncertainty = 0 | observation_arc = 63.18 yr (23,075 days) | aphelion = 2.4729 AU | perihelion = 2.3310 AU | semimajor = 2.4019 AU | eccentricity = 0.0295 | period = 3.72 yr (1,360 days) | mean_anomaly = 197.74° | mean_motion = {{Deg2DMS|0.2648|sup=ms}} / day | inclination = 7.8981° | asc_node = 105.50° | arg_peri = 236.47° | dimensions = 10.75 km {{small|(calculated)}}<ref name="lcdb" /><br />{{val|11.00|0.83}} km<ref name="AKARI" /><br />{{val|11.084|0.101}} km<ref name="Masiero-2014" /><br />{{val|11.554|0.074}} km<ref name="WISE" /> | rotation = {{val|8.899|0.0053}} h<ref name="Waszczak-2015" /> | albedo = {{val|0.1931|0.0198}}<ref name="WISE" /><br />0.20 {{small|(assumed)}}<ref name="lcdb" /><br />{{val|0.211|0.033}}<ref name="AKARI" /><br />{{val|0.224|0.023}}<ref name="Masiero-2014" /> | spectral_type = S<ref name="lcdb" /> | abs_magnitude = {{val|11.759|0.002}} {{small|(R)}}<ref name="Waszczak-2015" />{{·}}12.1<ref name="jpldata" /><ref name="AKARI" /><ref name="WISE" />{{·}}12.21<ref name="lcdb" />{{·}}{{val|12.40|0.29}}<ref name="Veres-2015" /> }}
'''2122 Pyatiletka''', provisional designation {{mp|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.<ref name="MPC-Pyatiletka" /> It was named for "pyatiletka", the first Five-Year Plan of the USSR.<ref name="springer" />
== 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.<ref name="jpldata" />
It was first identified as {{mp|1950 BE|1}} at Simeiz Observatory in 1950. The body's observation arc begins at Lowell Observatory in 1961, when it was identified as {{mp|1961 AL}}, 10 years prior to its official discovery observation at Nauchnyj.<ref name="MPC-Pyatiletka" />
== Physical characteristics ==
''Pyatiletka'' has been characterized as a stony S-type asteroid.<ref name="lcdb" />
=== 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 ({{small|U=1}}).<ref name="Waszczak-2015" /> As of 2017, no other lightcurve has been published.<ref name="lcdb" />
=== 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.<ref name="AKARI" /><ref name="Masiero-2014" /><ref name="WISE" /> 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.<ref name="lcdb" />
== 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.<ref name="springer" /> The official naming citation was published by the Minor Planet Center on 1 April 1980 ({{small|M.P.C. 5283}}).<ref name="MPC-Circulars-Archive" />
== References == {{reflist|30em|refs=
<ref name="jpldata">{{cite web |type = 2017-04-30 last obs. |title = JPL Small-Body Database Browser: 2122 Pyatiletka (1971 XB) |url = https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2002122 |publisher = Jet Propulsion Laboratory |accessdate = 11 June 2017}}</ref>
<ref name="springer">{{cite book |title = Dictionary of Minor Planet Names – (2122) Pyatiletka |last = Schmadel | first = Lutz D. |publisher = Springer Berlin Heidelberg |page = 172 |date = 2007 |isbn = 978-3-540-00238-3 |doi = 10.1007/978-3-540-29925-7_2123 |chapter = (2122) Pyatiletka }}</ref>
<ref name="MPC-Pyatiletka">{{cite web |title = 2122 Pyatiletka (1971 XB) |work = Minor Planet Center |url = https://www.minorplanetcenter.net/db_search/show_object?object_id=2122 |accessdate = 27 March 2017}}</ref>
<ref name="MPC-Circulars-Archive">{{cite web |title = MPC/MPO/MPS Archive |work = Minor Planet Center |url = https://www.minorplanetcenter.net/iau/ECS/MPCArchive/MPCArchive_TBL.html |accessdate = 27 March 2017}}</ref>
<ref name="Masiero-2014">{{cite journal |display-authors = 6 |first1 = Joseph R. |last1 = Masiero |first2 = T. |last2 = Grav |first3 = A. K. |last3 = Mainzer |first4 = C. R. |last4 = Nugent |first5 = J. M. |last5 = Bauer |first6 = R. |last6 = Stevenson |first7 = S. |last7 = Sonnett |date = August 2014 |title = Main-belt Asteroids with WISE/NEOWISE: Near-infrared Albedos |url = http://adsabs.harvard.edu/cgi-bin/bib_query?bibcode=2014ApJ...791..121M |journal = The Astrophysical Journal |volume = 791 |issue = 2 |page = 11 |bibcode = 2014ApJ...791..121M |doi = 10.1088/0004-637X/791/2/121 |arxiv = 1406.6645 |access-date= 27 March 2017}}</ref>
<ref name="lcdb">{{cite LCDB|number = 2122 |accessdate = 27 March 2017}}</ref>
<ref name="WISE">{{cite journal |display-authors = 6 |first1 = A. |last1 = Mainzer |first2 = T. |last2 = Grav |first3 = J. |last3 = Masiero |first4 = E. |last4 = Hand |first5 = J. |last5 = Bauer |first6 = D. |last6 = Tholen |first7 = R. S. |last7 = McMillan |first8 = T. |last8 = Spahr |first9 = R. M. |last9 = Cutri |first10 = E. |last10 = Wright |first11 = J. |last11 = Watkins |first12 = W. |last12 = Mo |first13 = C. |last13 = Maleszewski |date = November 2011 |title = NEOWISE Studies of Spectrophotometrically Classified Asteroids: Preliminary Results |journal = The Astrophysical Journal |volume = 741 |issue = 2 |page = 25 |bibcode = 2011ApJ...741...90M |doi = 10.1088/0004-637X/741/2/90 |arxiv = 1109.6407}}</ref>
<ref name="AKARI">{{cite journal |display-authors = 6 |first1 = Fumihiko |last1 = Usui |first2 = Daisuke |last2 = Kuroda |first3 = Thomas G. |last3 = Müller |first4 = Sunao |last4 = Hasegawa |first5 = Masateru |last5 = Ishiguro |first6 = Takafumi |last6 = Ootsubo |first7 = Daisuke |last7 = Ishihara |first8 = Hirokazu |last8 = Kataza |first9 = Satoshi |last9 = Takita |first10 = Shinki |last10 = Oyabu |first11 = Munetaka |last11 = Ueno |first12 = Hideo |last12 = Matsuhara |first13 = Takashi |last13 = Onaka |date = October 2011 |title = Asteroid Catalog Using Akari: AKARI/IRC Mid-Infrared Asteroid Survey |journal = Publications of the Astronomical Society of Japan |volume = 63 |issue = 5 |pages = 1117–1138 |bibcode = 2011PASJ...63.1117U |doi = 10.1093/pasj/63.5.1117 |doi-access= free }} ([http://vizier.cfa.harvard.edu/viz-bin/VizieR-5?-source=J/PASJ/63/1117/acua_v1&Num=2122 online], [https://core.ac.uk/download/pdf/43545172.pdf AcuA catalog p. 153])</ref>
<ref name="Waszczak-2015">{{cite journal |display-authors = 6 |first1 = Adam |last1 = Waszczak |first2 = Chan-Kao |last2 = Chang |first3 = Eran O. |last3 = Ofek |first4 = Russ |last4 = Laher |first5 = Frank |last5 = Masci |first6 = David |last6 = Levitan |first7 = Jason |last7 = Surace |first8 = Yu-Chi |last8 = Cheng |first9 = Wing-Huen |last9 = Ip |first10 = Daisuke |last10 = Kinoshita |first11 = George |last11 = Helou |first12 = Thomas A. |last12 = Prince |first13 = Shrinivas |last13 = Kulkarni |date = September 2015 |title = Asteroid Light Curves from the Palomar Transient Factory Survey: Rotation Periods and Phase Functions from Sparse Photometry |url = http://adsabs.harvard.edu/cgi-bin/bib_query?bibcode=2015AJ....150...75W |journal = The Astronomical Journal |volume = 150 |issue = 3 |page = 35 |bibcode = 2015AJ....150...75W |doi = 10.1088/0004-6256/150/3/75 |arxiv = 1504.04041 |access-date= 27 March 2017}}</ref>
<ref name="Veres-2015">{{cite journal |display-authors = 6 |first1 = Peter |last1 = Veres |first2 = Robert |last2 = Jedicke |first3 = Alan |last3 = Fitzsimmons |first4 = Larry |last4 = Denneau |first5 = Mikael |last5 = Granvik |first6 = Bryce |last6 = Bolin |first7 = Serge |last7 = Chastel |first8 = Richard J. |last8 = Wainscoat |first9 = William S. |last9 = Burgett |first10 = Kenneth C. |last10 = Chambers |first11 = Heather |last11 = Flewelling |first12 = Nick |last12 = Kaiser |first13 = Eugen A. |last13 = Magnier |first14 = Jeff S. |last14 = Morgan |first15 = Paul A. |last15 = Price |first16 = John L. |last16 = Tonry |first17 = Christopher |last17 = Waters |date = November 2015 |title = Absolute magnitudes and slope parameters for 250,000 asteroids observed by Pan-STARRS PS1 - Preliminary results |url = http://adsabs.harvard.edu/cgi-bin/bib_query?bibcode=2015Icar..261...34V |journal = Icarus |volume = 261 |pages = 34–47 |bibcode = 2015Icar..261...34V |doi = 10.1016/j.icarus.2015.08.007 |arxiv = 1506.00762 |access-date= 27 March 2017}}</ref>
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{{DEFAULTSORT:Pyatiletka}} 002122 Category:Discoveries by Tamara Mikhaylovna Smirnova Category:Named minor planets 19711214