{{Short description|Stony main-belt asteroid}} {{Use dmy dates|date=October 2019}} {{Infobox planet | minorplanet = yes | name = 1805 Dirikis | background = #D6D6D6 | image = 1805Dirikis (Lightcurve Inversion).png | image_scale = | caption = {{longitem|Lightcurve-based 3-D model of Dirikis|style=padding: 5px 0; line-height: 1.3em;}} | discovery_ref = <ref name="jpldata" /> | discovered = 1 April 1970 | discoverer = L. Chernykh | discovery_site = {{nowrap|Crimean Astrophysical Obs.}} | mpc_name = (1805) Dirikis | alt_names = 1970 GD{{·}}1942 EJ<br />1948 JH{{·}}1948 JM<br />{{mp|1950 TU|1}}{{·}}1953 EL<br />{{mp|1955 QL|1}}{{·}}1959 JP<br />1962 WP{{·}}{{mp|1962 XC|1}}<br />1964 FE | named_after = Matiss Dirikis {{small|(astronomer)}}<ref name="springer" /> | mp_category = main-belt{{·}}Themis<ref name="lcdb" /> | orbit_ref = <ref name="jpldata" /> | epoch = 4 September 2017 (JD 2458000.5) | uncertainty = 0 | observation_arc = 66.20 yr (24,178 days) | aphelion = 3.4915 AU | perihelion = 2.7911 AU | semimajor = 3.1413 AU | eccentricity = 0.1115 | period = 5.57 yr (2,034 days) | mean_anomaly = 235.42° | inclination = 2.5157° | asc_node = 78.926° | arg_peri = 86.389° | dimensions = {{val|22.05|1.37}} km<ref name="AKARI" /><br />25.53 km {{small|(derived)}}<ref name="lcdb" /><br />{{val|25.70|2.7}} km<ref name="SIMPS" /><br />{{val|27.228|0.251}} km<ref name="Masiero-2011" /><br />{{val|28.098|0.238}} km<ref name="WISE" /> | rotation = {{val|23.0|0.3}} h<ref name="geneva-obs" /><br />{{val|23.4543|}} h<ref name="Hanus-2013c" /> | albedo = 0.0746 {{small|(derived)}}<ref name="lcdb" /><br />{{val|0.0893|0.0076}}<ref name="WISE" /><br />{{val|0.095|0.007}}<ref name="Masiero-2011" /><br />{{val|0.1065|0.026}}<ref name="SIMPS" /><br />{{val|0.145|0.019}}<ref name="AKARI" /> | spectral_type = S<ref name="lcdb" /> | abs_magnitude = 11.0<ref name="AKARI" /><ref name="SIMPS" /><ref name="WISE" />{{·}}11.4<ref name="jpldata" /><ref name="lcdb" /> }}
'''1805 Dirikis''', provisional designation {{mp|1970 GD}}, is a stony Themistian asteroid from the outer region of the asteroid belt, approximately 26 kilometers in diameter.
It was discovered on 1 April 1970, by Russian astronomer Lyudmila Chernykh at the Crimean Astrophysical Observatory in Nauchnyj on the Crimean peninsula.<ref name="MPC-Dirikis" /> It was named for Latvian astronomer Matiss Dirikis.<ref name="springer" />
== Orbit and classification ==
The S-type asteroid is a member of the Themis family,<ref name="lcdb" /> a dynamical population of outer-belt asteroids with nearly coplanar ecliptical orbits. It orbits the Sun at a distance of 2.8–3.5 AU once every 5 years and 7 months (2,034 days). Its orbit has an eccentricity of 0.11 and an inclination of 3° with respect to the ecliptic.<ref name="jpldata" />
It was first observed at the Finnish Turku Observatory during WWII in 1942. The body's first used observation was its identification as {{mp|1955 QL|1}} at Goethe Link Observatory in 1955, extending the asteroid's observation arc by 15 years prior to its official discovery observation.<ref name="MPC-Dirikis" />
== Physical characteristics ==
=== Rotation period ===
A rotational lightcurve of Dirikis was obtained from photometric observations taken by French amateur astronomer René Roy In April 2003. It gave a rotation period of 23.0 hours with a brightness variation of 0.45 magnitude ({{small|U=2}}).<ref name="geneva-obs" /> A 2013-published period of 23.45 hours was derived in an international study ({{small|U=n.a.}}).<ref name="Hanus-2013c" />
=== Diameter and albedo ===
According to the surveys carried out by the Infrared Astronomical Satellite IRAS, the Japanese Akari satellite, and NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Dirikis measures between 22.05 and 28.10 kilometers in diameter, and its surface has an albedo between 0.089 and 0.145.<ref name="AKARI" /><ref name="SIMPS" /><ref name="Masiero-2011" /><ref name="WISE" /> The Collaborative Asteroid Lightcurve Link derives an albedo of 0.075 and calculates a diameter of 25.53 kilometers with an absolute magnitude of 11.4.<ref name="lcdb" />
== Naming ==
This minor planet was named for astronomer Matiss A. Dirikis (1923–1993), who was a member of the Astronomical Observatory at the University of Latvia, and chairman of the Latvian branch of the Astronomical–Geodetical Society of the U.S.S.R. His work on the motion of small Solar System bodies also contributed to the field of theoretical astronomy.<ref name="springer" /> The official {{MoMP|1805|naming citation}} was published by the Minor Planet Center on 1 January 1974 ({{small|M.P.C. 3569}}).<ref name="DoMP-Circular-dates" />
== References == <references>
<ref name="jpldata">{{cite web |type = 2016-12-25 last obs. |title = JPL Small-Body Database Browser: 1805 Dirikis (1970 GD) |url = https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2001805 |publisher = Jet Propulsion Laboratory |access-date = 3 June 2017}}</ref>
<ref name="springer">{{cite book |title = Dictionary of Minor Planet Names – (1805) Dirikis |last = Schmadel | first = Lutz D. |publisher = Springer Berlin Heidelberg |page = 145 |date = 2007 |isbn = 978-3-540-00238-3 |doi = 10.1007/978-3-540-29925-7_1806 |chapter = (1805) Dirikis }}</ref>
<ref name="MPC-Dirikis">{{cite web |title = 1805 Dirikis (1970 GD) |work = Minor Planet Center |url = https://www.minorplanetcenter.net/db_search/show_object?object_id=1805 |access-date = 16 December 2016}}</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 – (1805) Dirikis |last = Behrend |first = Raoul |publisher = Geneva Observatory |url = http://obswww.unige.ch/~behrend/page4cou.html#001805 |access-date = 16 December 2016}}</ref>
<ref name="lcdb">{{cite LCDB|number = 1805 |access-date = 16 December 2016}}</ref>
<ref name="SIMPS">{{cite journal |first1 = E. F. |last1 = Tedesco |first2 = P. V. |last2 = Noah |first3 = M. |last3 = Noah |first4 = S. D. |last4 = Price |date = October 2004 |title = IRAS Minor Planet Survey V6.0 |url = https://sbnarchive.psi.edu/pds3/iras/IRAS_A_FPA_3_RDR_IMPS_V6_0/data/diamalb.tab |journal = NASA Planetary Data System |volume = 12 |pages = IRAS-A-FPA-3-RDR-IMPS-V6.0 |bibcode = 2004PDSS...12.....T |access-date = 22 October 2019}}</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 }} ([http://vizier.cfa.harvard.edu/viz-bin/VizieR-5?-source=J/PASJ/63/1117/acua_v1&Num=1805 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="Hanus-2013c">{{cite journal |display-authors = 6 |first1 = J. |last1 = Hanus |first2 = M. |last2 = Broz |first3 = J. |last3 = Durech |first4 = B. D. |last4 = Warner |first5 = J. |last5 = Brinsfield |first6 = R. |last6 = Durkee |first7 = D. |last7 = Higgins |first8 = R. A. |last8 = Koff |first9 = J. |last9 = Oey |first10 = F. |last10 = Pilcher |first11 = R. |last11 = Stephens |first12 = L. P. |last12 = Strabla |first13 = Q. |last13 = Ulisse |first14 = R. |last14 = Girelli |date = November 2013 |title = An anisotropic distribution of spin vectors in asteroid families |journal = Astronomy and Astrophysics |volume = 559 |page = 19 |bibcode = 2013A&A...559A.134H |doi = 10.1051/0004-6361/201321993 |arxiv = 1309.4296}}</ref>
<ref name="Masiero-2011">{{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 = J. |last6 = Dailey |first7 = P. R. M. |last7 = Eisenhardt |first8 = R. S. |last8 = McMillan |first9 = T. B. |last9 = Spahr |first10 = M. F. |last10 = Skrutskie |first11 = D. |last11 = Tholen |first12 = R. G. |last12 = Walker |first13 = E. L. |last13 = Wright |first14 = E. |last14 = DeBaun |first15 = D. |last15 = Elsbury |first16 = T. IV |last16 = Gautier |first17 = S. |last17 = Gomillion |first18 = A. |last18 = Wilkins |date = November 2011 |title = Main Belt Asteroids with WISE/NEOWISE. I. Preliminary Albedos and Diameters |url = http://adsabs.harvard.edu/cgi-bin/bib_query?bibcode=2011ApJ...741...68M |journal = The Astrophysical Journal |volume = 741 |issue = 2 |page = 20 |bibcode = 2011ApJ...741...68M |doi = 10.1088/0004-637X/741/2/68 |arxiv = 1109.4096 |access-date= 16 December 2016}}</ref>
</references> <!-- 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|1805}} * {{JPL small body}}
{{Minor planets navigator |1804 Chebotarev |number=1805 |1806 Derice}} {{Small Solar System bodies}} {{Authority control}}
{{DEFAULTSORT:Dirikis}} 001805 Category:Discoveries by Lyudmila Chernykh Category:Named minor planets 19700401