{{Short description|Asteroid from the central regions of the asteroid belt}} {{Use dmy dates|date=October 2019}} {{Infobox planet | minorplanet = yes | name = 1541 Estonia | background = #D6D6D6 | image = | image_size = | caption = | discovery_ref = <ref name="jpldata" /> | discoverer = Y. Väisälä | discovery_site = Turku Observatory | discovered = 12 February 1939 | mpc_name = (1541) Estonia | alt_names = 1939 CK{{·}}1930 FE<br />1930 FV{{·}}{{mp|1950 RG|1}}<br />1950 SR{{·}}{{mp|1959 RF|1}}<br />A916 GE{{·}}A923 VE | pronounced = | named_after = Estonia<ref name="springer" /><br />{{small|(Baltic country)}} | mp_category = main-belt{{·}}{{small|(middle)}} | orbit_ref = <ref name="jpldata" /> | epoch = 4 September 2017 (JD 2458000.5) | uncertainty = 0 | observation_arc = 93.57 yr (34,176 days) | aphelion = 2.9610 AU | perihelion = 2.5761 AU | semimajor = 2.7685 AU | eccentricity = 0.0695 | period = 4.61 yr (1,683 days) | mean_anomaly = 346.22° | mean_motion = {{Deg2DMS|0.2140|sup=ms}} / day | inclination = 4.8750° | asc_node = 1.4553° | arg_peri = 192.84° | dimensions = {{val|19.53|0.40}} km<ref name="Masiero-2012" /><br />20.15 km {{small|(derived)}}<ref name="lcdb" /><br />{{val|20.56|6.71}} km<ref name="Nugent-2015" /><br />{{val|22.000|0.342}} km<ref name="Masiero-2014" /><br />{{val|23.89|1.35}} km<ref name="AKARI" /><br />{{val|24.542|0.096}} km<ref name="WISE" /> | rotation = {{val|10.1|1.0}} h<ref name="geneva-obs" /> | albedo = {{val|0.0976|0.0129}}<ref name="WISE" /><br />{{val|0.104|0.012}}<ref name="AKARI" /><br />{{val|0.12|0.13}}<ref name="Nugent-2015" /><br />0.1314 {{small|(derived)}}<ref name="lcdb" /><br />{{val|0.140|0.016}}<ref name="Masiero-2012" /> | spectral_type = SMASS {{=}} Xc<ref name="jpldata" />{{·}}X<ref name="lcdb" /> | abs_magnitude = 11.20<ref name="AKARI" /><ref name="WISE" />{{·}}11.30<ref name="lcdb" /><ref name="Masiero-2012" /><ref name="Nugent-2015" />{{·}}11.4<ref name="jpldata" />{{·}}{{val|11.56|0.24}}<ref name="Veres-2015" /> }}
'''1541 Estonia''' (provisional designation '''{{mp|1939 CK}}''') is an asteroid from the central regions of the asteroid belt, approximately 21 kilometers in diameter. It was discovered on 12 February 1939, by astronomer Yrjö Väisälä at the Iso-Heikkilä Observatory near Turku, Finland.<ref name="MPC-object" /> The asteroid was named after the Baltic country of Estonia.<ref name="springer" />
== Orbit and classification ==
Estonia is a non-family asteroid from the main belt's background population. It orbits the Sun in the central main belt at a distance of 2.6–3.0 AU once every 4 years and 7 months (1,683 days). Its orbit has an eccentricity of 0.07 and an inclination of 5° with respect to the ecliptic.<ref name="jpldata" />
The asteroid was first identified as {{mp|A916 GE}} at the Simeiz Observatory in April 1916. The body's observation arc begins with its identification as {{mp|A923 VE}} at Yerkes Observatory in November 1923, more than 15 years prior to its official discovery observation at Turku.<ref name="MPC-object" />
== Physical characteristics ==
In the SMASS classification, Estonia is an Xc-subtype asteroid; asteroids of the Xc subtype have characteristics intermediate of X-type asteroids and carbonaceous C-type asteroids.<ref name="jpldata" />
=== Rotation period ===
In November 2015, a rotational lightcurve of Estonia was obtained from photometric observations by French amateur astronomer René Roy. Lightcurve analysis gave a rotation period of 10.1 hours with a brightness amplitude of 0.13 magnitude ({{small|U=2-}}).<ref name="geneva-obs" />
=== Diameter and albedo ===
According to the surveys carried out by the Japanese Akari satellite and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Estonia measures between 19.53 and 24.542 kilometers in diameter and its surface has an albedo between 0.0976 and 0.140.<ref name="Masiero-2012" /><ref name="Nugent-2015" /><ref name="Masiero-2014" /><ref name="AKARI" /><ref name="WISE" />
The ''Collaborative Asteroid Lightcurve Link'' derives an albedo of 0.1314 and a diameter of 20.15 kilometers based on an absolute magnitude of 11.3.<ref name="lcdb" />
== Naming ==
This minor planet was named after the Baltic country of Estonia, just south of the Gulf of Finland and Finland itself. The two countries are inhabited by related Balto-Finnic peoples. Estonia regained independence from Soviet rule in 1991.<ref name="springer" /> The official {{MoMP|1541|naming citation}} was published by the Minor Planet Center in January 1956 ({{small|M.P.C. 1350}}).<ref name="DoMP-Circular-dates" />
== References == {{reflist|30em|refs=
<ref name="jpldata">{{cite web |type = 2017-06-04 last obs. |title = JPL Small-Body Database Browser: 1541 Estonia (1939 CK) |url = https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2001541 |publisher = Jet Propulsion Laboratory |accessdate = 20 September 2017}}</ref>
<ref name="springer">{{cite book |title = Dictionary of Minor Planet Names – (1541) Estonia |last = Schmadel | first = Lutz D. |publisher = Springer Berlin Heidelberg |page = 122 |date = 2007 |isbn = 978-3-540-00238-3 |doi = 10.1007/978-3-540-29925-7_1542 |chapter = (1541) Estonia }}</ref>
<ref name="MPC-object">{{cite web |title = 1541 Estonia (1939 CK) |work = Minor Planet Center |url = https://www.minorplanetcenter.net/db_search/show_object?object_id=1541 |accessdate = 20 September 2017}}</ref>
<ref name="DoMP-Circular-dates">{{cite book |title = Dictionary of Minor Planet Names – Addendum to Fifth Edition (2006–2008) |year = 2009 |url = https://archive.org/details/dictionaryminorp2008schm |url-access = limited |chapter = Appendix – Publication Dates of the MPCs |last = Schmadel |first=Lutz D. |publisher = Springer Berlin Heidelberg |page = [https://archive.org/details/dictionaryminorp2008schm/page/n230 221] |isbn = 978-3-642-01964-7 |doi = 10.1007/978-3-642-01965-4}}</ref>
<ref name="geneva-obs">{{cite web |title = Asteroids and comets rotation curves – (1541) Estonia |last = Behrend |first = Raoul |publisher = Geneva Observatory |url = http://obswww.unige.ch/~behrend/page4cou.html#001541 |accessdate = 20 September 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= 20 September 2017}}</ref>
<ref name="lcdb">{{cite LCDB|number = 1541 |accessdate = 20 September 2017}}</ref>
<ref name="Masiero-2012">{{cite journal |display-authors = 6 |first1 = Joseph R. |last1 = Masiero |first2 = A. K. |last2 = Mainzer |first3 = T. |last3 = Grav |first4 = J. M. |last4 = Bauer |first5 = R. M. |last5 = Cutri |first6 = C. |last6 = Nugent |first7 = M. S. |last7 = Cabrera |date = November 2012 |title = Preliminary Analysis of WISE/NEOWISE 3-Band Cryogenic and Post-cryogenic Observations of Main Belt Asteroids |url = http://adsabs.harvard.edu/cgi-bin/bib_query?bibcode=2012ApJ...759L...8M |journal = The Astrophysical Journal Letters |volume = 759 |issue = 1 |page = 5 |bibcode = 2012ApJ...759L...8M |doi = 10.1088/2041-8205/759/1/L8 |arxiv = 1209.5794 |access-date= 20 September 2017}}</ref>
<ref name="Nugent-2015">{{cite journal |display-authors = 6 |first1 = C. R. |last1 = Nugent |first2 = A. |last2 = Mainzer |first3 = J. |last3 = Masiero |first4 = J. |last4 = Bauer |first5 = R. M. |last5 = Cutri |first6 = T. |last6 = Grav |first7 = E. |last7 = Kramer |first8 = S. |last8 = Sonnett |first9 = R. |last9 = Stevenson |first10 = E. L. |last10 = Wright |date = December 2015 |title = NEOWISE Reactivation Mission Year One: Preliminary Asteroid Diameters and Albedos |url = http://adsabs.harvard.edu/cgi-bin/bib_query?bibcode=2015ApJ...814..117N |journal = The Astrophysical Journal |volume = 814 |issue = 2 |page = 13 |bibcode = 2015ApJ...814..117N |doi = 10.1088/0004-637X/814/2/117 |arxiv = 1509.02522 |access-date= 20 September 2017}}</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=1541 online], [https://core.ac.uk/download/pdf/43545172.pdf AcuA catalog p. 153])</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="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= 20 September 2017}}</ref>
}} <!-- end of reflist -->
== External links == * [http://www.minorplanet.info/PHP/lcdbsummaryquery.php Asteroid Lightcurve Database (LCDB)], 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] – Observatoire de Genève, Raoul Behrend * [https://www.minorplanetcenter.net/iau/lists/NumberedMPs000001.html Discovery Circumstances: Numbered Minor Planets (1)-(5000)] – Minor Planet Center * {{AstDys|1541}} * {{JPL small body}}
{{Minor planets navigator |1540 Kevola |number=1541 |1542 Schalén}} {{Small Solar System bodies}} {{Authority control}}
{{DEFAULTSORT:Estonia}} 001541 Category:Discoveries by Yrjö Väisälä Category:Named minor planets 001541 19390212