{{Short description|Stony asteroid and near-Earth object of the Amor group}} {{Use dmy dates|date=October 2019}} {{Infobox planet | minorplanet = yes | name = 21088 Chelyabinsk | background = #FFC2E0 | image = | caption = | discovery_ref = <ref name="jpldata" /> | discovered = 30 January 1992 | discoverer = E. W. Elst | discovery_site = La Silla Obs. | mpc_name = (21088) Chelyabinsk | alt_names = {{mp|1992 BL|2}} | named_after = {{nowrap|Chelyabinsk<ref name="MPC-object" /> {{small|(city and meteor)}}}} | mp_category = NEO{{·}}Amor<ref name="jpldata" /><ref name="MPC-object" /><br />Mars-crosser | orbit_ref = <ref name="jpldata" /> | epoch = 4 September 2017 (JD 2458000.5) | uncertainty = 0 | observation_arc = 27.41 yr (10,012 days) | aphelion = 2.1135 AU | perihelion = 1.2996 AU | semimajor = 1.7065 AU | eccentricity = 0.2384 | period = 2.23 yr (814 days) | mean_anomaly = 318.92° | mean_motion = {{Deg2DMS|0.4421|sup=ms}} / day | inclination = 38.455° | asc_node = 297.85° | arg_peri = 27.133° | moid = 0.3083 AU{{·}}120.1 LD | dimensions = {{val|2.79|0.10}} km<ref name="Nugent-2016" /><br />{{val|3.46|0.25}} km<ref name="AKARI" /><br />4.23 km {{small|(taken)}}<ref name="lcdb" /><br />{{val|4.231|0.113}} km<ref name="WISE" /><ref name="Mainzer-2011" /><br />{{val|4.232}} km<ref name="Pravec-2012b" /> | rotation = {{val|22.426|0.02}} h{{efn|name=lcdb-Pravec}}{{efn|name=lightcurve-plot}}<br />{{val|22.49}} h{{efn|name=lcdb-Pravec}} | albedo = {{val|0.1794}}<ref name="Pravec-2012b" /><br />0.206<ref name="WISE" /><br />{{val|0.257|0.038}}<ref name="AKARI" /><br />{{val|0.26|0.32}}<ref name="Thomas-2011b" /><br />{{val|0.37|0.06}}<ref name="Nugent-2016" /> | spectral_type = Q<ref name="Thomas-2014" />{{·}}L<ref name="Carry-2016" />{{·}}S<ref name="lcdb" /><br />B–V = {{val|0.855|0.073}}<ref name="Ye-2011" /><br />{{nowrap|1=V–R = {{val|0.464|0.015}}<ref name="Ye-2011" /> }}<br />V–I = {{val|0.910|0.032}}<ref name="Ye-2011" /> | abs_magnitude = {{val|13.86|0.14}} {{small|(R)}}{{efn|name=lcdb-Pravec}}{{·}}14.00<ref name="Carry-2016" />{{·}}14.2<ref name="WISE" />{{·}}{{val|14.29|0.24}}<ref name="Veres-2015" />{{·}}14.3<ref name="jpldata" />{{·}}{{val|14.35|0.149}}<ref name="lcdb" /><ref name="Pravec-2012b" />{{·}}14.40<ref name="AKARI" /> }}
'''21088 Chelyabinsk''' (provisional designation '''{{mp|1992 BL|2}}''') is a stony asteroid and near-Earth object of the Amor group, approximately 4 kilometers in diameter. It was discovered on 30 January 1992, by Belgian astronomer Eric Elst at ESO's La Silla Observatory in northern Chile. The asteroid was named after the Russian city of Chelyabinsk and for its spectacular Chelyabinsk meteor event in 2013.<ref name="MPC-object" /> It is not related to the Chelyabinsk impactor.
== Classification and orbit == Chelyabinsk orbits the Sun at a distance of 1.3–2.1 AU once every 2 years and 3 months (814 days). Its orbit has an eccentricity of 0.24 and an inclination of 38° with respect to the ecliptic. A first precovery was taken during the Digitized Sky Survey at the Australia Siding Spring Observatory in January 1990, extending the asteroid's observation arc by 2 years prior to its official discovery at La Silla.<ref name="MPC-object" />
=== Close approaches === As a near-Earth object, Chelyabinsk has a low Earth minimum orbit intersection distance of {{convert |0.3083 |AU |km |sigfig=3 |abbr=on}}, which translates into 120.1 lunar distances (LD). This is, however, far too large to make it a potentially hazardous asteroid, which have intersection distances of less than 20 LD.<ref name="jpldata" /> It also crosses the orbit of Mars at 1.666 AU which makes it a Mars-crossing asteroid. In August 2142, it will approach Mars at {{convert |0.0986 |AU |km |sigfig=3 |abbr=on}}.<ref name="jpldata" />
== Physical characteristics == Chelyabinsk has been characterized as both a Q-type and L-type asteroid.<ref name="Thomas-2014" /><ref name="Carry-2016" /> It is also a generically assumed S-type asteroid.<ref name="lcdb" />
=== Lightcurves === Two rotational light-curves of Chelyabinsk were obtained by Czech astronomer Petr Pravec at Ondřejov Observatory in December 2002 and September 2004, respectively. They gave a rotation period of 22.490 and {{val|22.426}} hours, each with a brightness variation of 0.13 magnitude ({{small|U=n.a./3-}}).{{efn|name=lcdb-Pravec}}{{efn|name=lightcurve-plot}}
=== Diameter and albedo === According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer (WISE), Chelyabinsk measures between 2.79 and 4.2 kilometers in diameter and its surface has an albedo between 0.21 and 0.37,<ref name="WISE" /><ref name="Mainzer-2011" /><ref name="Pravec-2012b" /> while observations by the Japanese Akari satellite gave an albedo of 0.26 and a diameter of 3.5 kilometers.<ref name="AKARI" /> The ''Collaborative Asteroid Lightcurve Link'' adopts Petr Pravec's revised WISE results, that is, a diameter of 4.23 kilometers and an albedo of 0.179 based on an absolute magnitude of 14.35.<ref name="lcdb" /><ref name="Pravec-2012b" />
== Naming == This minor planet is named after the Russian city Chelyabinsk, located in the Ural region. The city is well known for the Chelyabinsk meteor, a 20-meter sized, extremely bright fireball that exploded to the south of the city at an altitude of 30 kilometers on 15 February 2013. The indirect effects of the explosion injured more than 1,500 people.<ref name="MPC-object" /> The official naming citation was published by the Minor Planet Center (MPC) on 21 August 2013 ({{small|M.P.C. 84674}}).<ref name="MPC-Circulars-Archive" />
=== Erratum === Originally, the name "Chelyabinsk" was erroneously given by the MPC to the numerically similar asteroid {{LoMP|20188|{{mp|(20188) 1997 AC|18}}}} on 22 July ({{small|M.P.C. 84379}}). The wrong designation {{mp|20188 Chelyabinsk}} was deleted in the subsequent publication of the Minor Planet Circulars on 21 August 2013 ({{small|M.P.C. 84385}}) <ref name="MPC-Circulars-Archive" />
== Notes == {{notelist|refs=
{{efn|name=lcdb-Pravec|1=Pravec (2002 and 2004) web: rotation period of 22.49 and {{val|22.426|0.02}} hours, both with a brightness amplitude of {{val|0.13}} mag. Summary figures of (21088) Chelyabinsk at the [http://www.minorplanet.info/PHP/generateOneAsteroidInfo.php?AstInfo=21088%7CChelyabinsk LCDB] and [http://www.asu.cas.cz/~ppravec/neo.htm Pravec, P.; Wolf, M.; Sarounova, L. (2002/2004)]}}
{{efn|name=lightcurve-plot|1=[http://www.asu.cas.cz/~asteroid/21088_a4.png Lightcurve plot] by Pravec from 7 June 2005 with period of 22.431 hours. [http://www.asu.cas.cz/~ppravec/newres.txt Data sheet] from unpublished observations at [http://www.asu.cas.cz/~ppravec/neo.htm Ondrejov Asteroid Photometry Project]}}
}} <!-- end of notelist -->
== References == <references>
<ref name="jpldata">{{cite web |type = 2016-02-19 last obs. |title = JPL Small-Body Database Browser: 21088 Chelyabinsk (1992 BL2) |url = https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2021088 |publisher = Jet Propulsion Laboratory |accessdate = 12 October 2016 |archive-date = 20 September 2020 |archive-url = https://web.archive.org/web/20200920032301/https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2021088 |url-status = live }}</ref>
<ref name="MPC-object">{{cite web |title = 21088 Chelyabinsk (1992 BL2) |work = Minor Planet Center |url = https://www.minorplanetcenter.net/db_search/show_object?object_id=21088 |accessdate = 12 October 2016 |archive-date = 4 March 2016 |archive-url = https://web.archive.org/web/20160304095848/http://www.minorplanetcenter.net/db_search/show_object?object_id=21088 |url-status = live }}</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 = 12 October 2016 |archive-date = 7 October 2010 |archive-url = https://web.archive.org/web/20101007190852/https://www.minorplanetcenter.net/iau/ECS/MPCArchive/MPCArchive_TBL.html |url-status = live }}</ref>
<ref name="Mainzer-2011">{{cite journal |display-authors = 6 |first1 = A. |last1 = Mainzer |first2 = T. |last2 = Grav |first3 = J. |last3 = Bauer |first4 = J. |last4 = Masiero |first5 = R. S. |last5 = McMillan |first6 = R. M. |last6 = Cutri |first7 = R. |last7 = Walker |first8 = E. |last8 = Wright |first9 = P. |last9 = Eisenhardt |first10 = D. J. |last10 = Tholen |first11 = T. |last11 = Spahr |first12 = R. |last12 = Jedicke |first13 = L. |last13 = Denneau |first14 = E. |last14 = DeBaun |first15 = D. |last15 = Elsbury |first16 = T. |last16 = Gautier |first17 = S. |last17 = Gomillion |first18 = E. |last18 = Hand |first19 = W. |last19 = Mo |first20 = J. |last20 = Watkins |first21 = A. |last21 = Wilkins |first22 = G. L. |last22 = Bryngelson |first23 = A. |last23 = Del Pino Molina |first24 = S. |last24 = Desai |first25 = M. |last25 = Gómez Camus |first26 = S. L. |last26 = Hidalgo |first27 = I. |last27 = Konstantopoulos |first28 = J. A. |last28 = Larsen |first29 = C. |last29 = Maleszewski |first30 = M. A. |last30 = Malkan |first31 = J.-C. |last31 = Mauduit |first32 = B. L. |last32 = Mullan |first33 = E. W. |last33 = Olszewski |first34 = J. |last34 = Pforr |first35 = A. |last35 = Saro |first36 = J. V. |last36 = Scotti |first37 = L. H. |last37 = Wasserman |date = December 2011 |title = NEOWISE Observations of Near-Earth Objects: Preliminary Results |journal = The Astrophysical Journal |volume = 743 |issue = 2 |page = 17 |bibcode = 2011ApJ...743..156M |doi = 10.1088/0004-637X/743/2/156 |arxiv = 1109.6400 |s2cid = 239991 }}</ref>
<ref name="lcdb">{{cite LCDB|number = 21088 |accessdate = 12 October 2016 |archive-date = 13 September 2020 |archive-url = https://web.archive.org/web/20200913121653/http://www.minorplanet.info/PHP/generateOneAsteroidInfo.php?AstInfo=21088%7CChelyabinsk |url-status = live }}</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=21088 online] {{Webarchive|url=https://web.archive.org/web/20240903000959/http://vizier.cfa.harvard.edu/viz-bin/VizieR-5?-source=J/PASJ/63/1117/acua_v1&Num=21088 |date=3 September 2024 }}, [https://core.ac.uk/download/pdf/43545172.pdf AcuA catalog p. 153] {{Webarchive|url=https://web.archive.org/web/20190325134554/https://core.ac.uk/download/pdf/43545172.pdf |date=25 March 2019 }})</ref>
<ref name="Pravec-2012b">{{Cite journal |first1 = Petr |last1 = Pravec |first2 = Alan W. |last2 = Harris |first3 = Peter |last3 = Kusnirák |first4 = Adrián |last4 = Galád |first5 = Kamil |last5 = Hornoch |date = September 2012 |title = Absolute magnitudes of asteroids and a revision of asteroid albedo estimates from WISE thermal observations |journal = Icarus |volume = 221 |issue = 1 |pages = 365–387 |bibcode = 2012Icar..221..365P |doi = 10.1016/j.icarus.2012.07.026 |hdl= 11104/0217021 |hdl-access= free }}</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 |s2cid = 35447010 }}</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 |journal = Icarus |volume = 261 |pages = 34–47 |bibcode = 2015Icar..261...34V |doi = 10.1016/j.icarus.2015.08.007 |arxiv = 1506.00762 |s2cid = 53493339 }}</ref>
<ref name="Carry-2016">{{Cite journal |first1 = B. |last1 = Carry |first2 = E. |last2 = Solano |first3 = S. |last3 = Eggl |first4 = F. E. |last4 = DeMeo |date = April 2016 |title = Spectral properties of near-Earth and Mars-crossing asteroids using Sloan photometry |journal = Icarus |volume = 268 |pages = 340–354 |bibcode = 2016Icar..268..340C |doi = 10.1016/j.icarus.2015.12.047 |arxiv = 1601.02087 |s2cid = 119258489 }}</ref>
<ref name="Thomas-2011b">{{cite journal |display-authors = 6 |first1 = C. A. |last1 = Thomas |first2 = D. E. |last2 = Trilling |first3 = J. P. |last3 = Emery |first4 = M. |last4 = Mueller |first5 = J. L. |last5 = Hora |first6 = L. A. M. |last6 = Benner |first7 = B. |last7 = Bhattacharya |first8 = W. F. |last8 = Bottke |first9 = S. |last9 = Chesley |first10 = M. |last10 = Delbó |first11 = G. |last11 = Fazio |first12 = A. W. |last12 = Harris |first13 = A. |last13 = Mainzer |first14 = M. |last14 = Mommert |first15 = A. |last15 = Morbidelli |first16 = B. |last16 = Penprase |first17 = H. A. |last17 = Smith |first18 = T. B. |last18 = Spahr |first19 = J. A. |last19 = Stansberry |date = September 2011 |title = ExploreNEOs. V. Average Albedo by Taxonomic Complex in the Near-Earth Asteroid Population |journal = The Astronomical Journal |volume = 142 |issue = 3 |page = 12 |bibcode = 2011AJ....142...85T |doi = 10.1088/0004-6256/142/3/85 |doi-access= free }}</ref>
<ref name="Thomas-2014">{{cite journal |first1 = Cristina A. |last1 = Thomas |first2 = Joshua P. |last2 = Emery |first3 = David E. |last3 = Trilling |first4 = Marco |last4 = Delbó |first5 = Joseph L. |last5 = Hora |first6 = Michael |last6 = Mueller |date = January 2014 |title = Physical characterization of Warm Spitzer-observed near-Earth objects |journal = Icarus |volume = 228 |pages = 217–246 |bibcode = 2014Icar..228..217T |doi = 10.1016/j.icarus.2013.10.004 |arxiv = 1310.2000|s2cid = 119278697 }}</ref>
<ref name="Ye-2011">{{Cite journal |author = Ye, Q.-z. |date = February 2011 |title = BVRI Photometry of 53 Unusual Asteroids |journal = The Astronomical Journal |volume = 141 |issue = 2 |page = 8 |bibcode = 2011AJ....141...32Y |doi = 10.1088/0004-6256/141/2/32 |arxiv = 1011.0133 |s2cid = 119307210 }}</ref>
<ref name="Nugent-2016">{{cite journal |display-authors = 6 |first1 = C. R. |last1 = Nugent |first2 = A. |last2 = Mainzer |first3 = J. |last3 = Bauer |first4 = R. M. |last4 = Cutri |first5 = E. A. |last5 = Kramer |first6 = T. |last6 = Grav |first7 = J. |last7 = Masiero |first8 = S. |last8 = Sonnett |first9 = E. L. |last9 = Wright |date = September 2016 |title = NEOWISE Reactivation Mission Year Two: Asteroid Diameters and Albedos |journal = The Astronomical Journal |volume = 152 |issue = 3 |page = 12 |bibcode = 2016AJ....152...63N |doi = 10.3847/0004-6256/152/3/63 |arxiv = 1606.08923 |doi-access = free }}</ref>
</references> <!-- end of reflist -->
== External links == * [http://www.minorplanet.info/PHP/lcdbsummaryquery.php Asteroid Lightcurve Database (LCDB)] {{Webarchive|url=https://web.archive.org/web/20171210173955/http://www.minorplanet.info/PHP/lcdbsummaryquery.php |date=10 December 2017 }}, query form ([http://www.minorplanet.info/lightcurvedatabase.html info] {{Webarchive|url=https://web.archive.org/web/20171216050541/http://www.minorplanet.info/lightcurvedatabase.html |date=16 December 2017 }}) * [https://books.google.com/books?id=aeAg1X7afOoC&pg Dictionary of Minor Planet Names], Google books * [http://obswww.unige.ch/~behrend/page_cou.html Asteroids and comets rotation curves, CdR] {{Webarchive|url=https://web.archive.org/web/20160729213840/http://obswww.unige.ch/~behrend/page_cou.html |date=29 July 2016 }} – Observatoire de Genève, Raoul Behrend * {{NeoDys|21088}} * {{ESA-SSA|21088|Chelyabinsk}} * {{JPL small body}}
{{Minor planets navigator |21087 Petsimpallas |number=21088 |21089 Mochizuki}} {{Small Solar System bodies}} {{Authority control}}
{{DEFAULTSORT:Chelyabinsk}} 021088 Category:Discoveries by Eric Walter Elst Category:Named minor planets 19920130