{{Short description|Main-belt asteroid}} {{Use dmy dates|date=October 2019}} {{Infobox planet | minorplanet = yes | name = 764 Gedania | background = #D6D6D6 | image = | image_size = | caption = | discovery_ref = <ref name="MPC-object" /> | discoverer = F. Kaiser | discovery_site = Heidelberg Obs. | discovered = 26 September 1913 | mpc_name = (764) Gedania | alt_names = A913 SF{{·}}A902 WD<br />A908 YE{{·}}A918 TA<br />1913 SU | pronounced = {{IPAc-en|g|ᵻ|'|d|eɪ|n|i|ə}} | named_after = City of Gdańsk<ref name="springer" /> | mp_category = {{plainlist| * main-belt<ref name="MPC-object" />{{·}}{{small|(outer)}}<ref name="jpldata" /> * background<ref name="AstDys-object" /><ref name="Ferret" /><ref name="Zappala-family" /> }} | orbit_ref = <ref name="jpldata" /> | epoch = 31 May 2020 (JD 2459000.5) | uncertainty = 0 | observation_arc = 117.43 yr (42,893 d) | aphelion = 3.5027 AU | perihelion = 2.9000 AU | semimajor = 3.2013 AU | eccentricity = 0.0941 | period = 5.73 yr (2,092 d) | mean_anomaly = 242.58° | mean_motion = {{Deg2DMS|0.1721|sup=ms}} / day | inclination = 10.018° | asc_node = 258.94° | arg_peri = 156.65° | mean_diameter = {{plainlist| * {{val|58.28|1.4|ul=km}}<ref name="SIMPS" /> * {{val|64.338|14.27|u=km}}<ref name="Masiero-2017" /> * {{val|74.59|1.39|u=km}}<ref name="AKARI" /> }} | rotation = {{val|24.9751|0.0007|ul=h}}<ref name="geneva-obs" /> | albedo = {{plainlist| * {{val|0.052|0.002}}<ref name="AKARI" /> * {{val|0.0608|0.03}}<ref name="Masiero-2017" /> * {{val|0.0840|0.004}}<ref name="SIMPS" /> }} | spectral_type = {{plainlist| * Tholen {{=}} C<ref name="jpldata" /> * Caa {{small|(S3OS2-TH)}}<ref name="Lazzaro-2004" /> * Ch {{small|(S3OS2-BB)}}<ref name="Lazzaro-2004" /> * {{nowrap|B–V {{=}} {{val|0.737|0.014}}<ref name="jpldata" />}} * U–B {{=}} {{val|0.400|0.043}}<ref name="jpldata" /> }} | abs_magnitude = {{plainlist| * 9.6<ref name="jpldata" /> * 9.7<ref name="MPC-object" />}} }}
'''764 Gedania''' (''prov. designation:'' {{mp|A913 SF}} ''or'' {{mp|1913 SU}}) is a large background asteroid from the outer regions of the asteroid belt, approximately {{convert|60|km|mi|abbr=off|sigfig=2|sp=us}} in diameter. It was discovered on 26 September 1913, by German astronomer Franz Kaiser at the Heidelberg-Königstuhl State Observatory in southwest Germany.<ref name="MPC-object" /> The carbonaceous C-type asteroid has a rotation period of 24.98 hours. It was named after the Polish city of Gdańsk where the discoverer was an assistant at the observatory during the 1920s.<ref name="springer" />
== Orbit and classification ==
''Gedania'' is a non-family asteroid of the main belt's background population when applying the hierarchical clustering method to its proper orbital elements.<ref name="AstDys-object" /><ref name="Ferret" /><ref name="Zappala-family" /> It orbits the Sun in the outer asteroid belt at a distance of 2.9–3.5 AU once every 5 years and 9 months (2,092 days; semi-major axis of 3.2 AU). Its orbit has an eccentricity of 0.09 and an inclination of 10° with respect to the ecliptic.<ref name="jpldata" /> The body's observation arc begins with its first observation as {{mp|A902 WD}} at Heidelberg Observatory in November 1902, almost 11 years prior to its official discovery observation by Franz Kaiser.<ref name="MPC-object" />
== Naming ==
This minor planet was named after the Latin name of the city of Gdańsk, Poland (formerly Free City of Danzig) where the discoverer, Franz Kaiser (1891–1962), was an assistant at the observatory during the early 1920s. The official naming citation was mentioned in ''The Names of the Minor Planets'' by Paul Herget in 1955 ({{small|H 77}}). Asteroid 1419 Danzig was also named by its German name for the city of Gdańsk.<ref name="springer" />
== Physical characteristics ==
In the Tholen classification, ''Gedania'' is a common carbonaceous C-type asteroid.<ref name="jpldata" /> It has also been classified as a hydrated Ch-type and as a Caa type in the Tholen- and SMASS-like taxonomic variant of the Small Solar System Objects Spectroscopic Survey (S3OS2).<ref name="Ferret" /><ref name="Lazzaro-2004" />
=== Rotation period ===
In February 2006, a rotational lightcurve of ''Gedania'' was obtained from photometric observations by collaborating astronomers Roberto Crippa, Federico Manzini {{Obscode|A12}}, René Roy, Donn Starkey, Raoul Behrend and Laurent Bernasconi. Lightcurve analysis gave a rotation period of {{val|24.9751|0.0007}} hours with a brightness variation of {{val|0.35|0.01}} magnitude ({{small|U=2}}).<ref name="geneva-obs" /> Observations by Aznar, Brinsfield and Pál, gave an alternative period determination of {{val|19.16|0.04}}, {{val|24.817|0.005}} and {{val|25.1172|0.0005}} hours, respectively ({{small|U=2/2/2}}).<ref name="lcdb" /><ref name="Brinsfield-2010a" /><ref name="Pal-2020" />
=== Diameter and albedo ===
According to the surveys carried out by the Infrared Astronomical Satellite IRAS, the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer and the Japanese Akari satellite, ''Gedania'' measures {{val|58.28|1.4}}, {{val|64.338|14.27}} and {{val|74.59|1.39}} kilometers in diameter and its surface has an albedo of {{val|0.0840|0.004}}, {{val|0.0608|0.03}} and {{val|0.052|0.002}}, respectively.<ref name="SIMPS" /><ref name="Masiero-2017" /><ref name="AKARI" /> The ''Collaborative Asteroid Lightcurve Link'' derives an albedo of 0.0754 and a diameter of 58.18 kilometers based on an absolute magnitude of 9.6.<ref name="lcdb" /> An alternative mean-diameter measurement published by the WISE team gave ({{val|66.30|18.01|u=km}}) with corresponding albedo of ({{val|0.04|0.05}}).<ref name="lcdb" /> On 5 February 2006, an asteroid occultation of ''Gedania'' gave a best-fit ellipse dimension of ({{val|58.0|x|58.0|u=km}}), with a poor quality rating of 1. These timed observations are taken when the asteroid passes in front of a distant star.<ref name="Ferret" />
== References == {{reflist|30em|refs=
<ref name="jpldata">{{cite web |type = 2020-04-28 last obs. |title = JPL Small-Body Database Browser: 764 Gedania (A913 SF) |url = https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2000764 |publisher = Jet Propulsion Laboratory |access-date = 28 May 2020}}</ref>
<ref name="springer">{{cite book |title = Dictionary of Minor Planet Names |last = Schmadel | first = Lutz D. |publisher = Springer Berlin Heidelberg |chapter = (764) Gedania |page = 72 |date = 2007 |doi = 10.1007/978-3-540-29925-7_765 |isbn = 978-3-540-00238-3}}</ref>
<ref name="MPC-object">{{cite web |title = 764 Gedania (A913 SF) |work = Minor Planet Center |url = https://www.minorplanetcenter.net/db_search/show_object?object_id=764 |access-date = 28 May 2020}}</ref>
<ref name="geneva-obs">{{cite web |title = Asteroids and comets rotation curves – (764) Gedania |last = Behrend |first = Raoul |publisher = Geneva Observatory |url = http://obswww.unige.ch/~behrend/page3cou.html#000764 |access-date = 28 May 2020}}</ref>
<ref name="lcdb">{{cite LCDB|number = 764 |access-date = 28 May 2020}}</ref>
<ref name="Masiero-2017">{{Cite journal |display-authors = 6 |first1 = Joseph R. |last1 = Masiero |first2 = C. |last2 = Nugent |first3 = A. K. |last3 = Mainzer |first4 = E. L. |last4 = Wright |first5 = J. M. |last5 = Bauer |first6 = R. M. |last6 = Cutri |first7 = T. |last7 = Grav |first8 = E. |last8 = Kramer |first9 = S. |last9 = Sonnett |date = October 2017 |title = NEOWISE Reactivation Mission Year Three: Asteroid Diameters and Albedos |journal = The Astronomical Journal |volume = 154 |issue = 4 |page = 10 |bibcode = 2017AJ....154..168M |doi = 10.3847/1538-3881/aa89ec |arxiv = 1708.09504 |doi-access = free }}</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= }} ([http://vizier.cfa.harvard.edu/viz-bin/VizieR-5?-source=J/PASJ/63/1117/acua_v1&Num=764 online], [https://core.ac.uk/download/pdf/43545172.pdf AcuA catalog p. 153])</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 = 28 May 2020}}</ref>
<ref name="Brinsfield-2010a">{{cite journal |last1 = Brinsfield |first1 = James W. |date = January 2010 |title = Asteroid Lightcurve Analysis at the Via Capote Observatory: 2009 3rd Quarter |journal = Minor Planet Bulletin |url = http://www.minorplanet.info/MPB/issues/MPB_37-1.pdf |volume = 37 |issue = 1 |pages = 19–20 |bibcode = 2010MPBu...37...19B |issn = 1052-8091}}</ref>
<ref name="Pal-2020">{{cite journal |display-authors = 6 |last1 = Pál |first1 = András |last2 = Szakáts |first2 = Róbert |last3 = Kiss |first3 = Csaba |last4 = Bódi |first4 = Attila |last5 = Bognár |first5 = Zsófia |last6 = Kalup |first6 = Csilla |last7 = Kiss |first7 = László L. |last8 = Marton |first8 = Gábor |last9 = Molnár |first9 = László |last10 = Plachy |first10 = Emese |last11 = Sárneczky |first11 = Krisztián |last12 = Szabó |first12 = Gyula M. |last13 = Szabó |first13 = Róbert |date = March 2020 |title = Solar System Objects Observed with TESS—First Data Release: Bright Main-belt and Trojan Asteroids from the Southern Survey |journal = The Astrophysical Journal Supplement Series |volume = 247 |issue = 1 |page = 26 |bibcode = 2020ApJS..247...26P |issn = 0067-0049 |doi = 10.3847/1538-4365/ab64f0 |arxiv = 2001.05822 |doi-access = free }}</ref>
<ref name="Ferret">{{cite web |title = Asteroid 764 Gedania |work = Small Bodies Data Ferret |url = https://sbntools.psi.edu/ferret/SimpleSearch/results.action?targetName=764+Gedania |access-date = 28 May 2020}}</ref>
<ref name="AstDys-object">{{cite web |title = Asteroid 764 Gedania – Proper Elements |publisher = AstDyS-2, Asteroids – Dynamic Site |url = https://newton.spacedys.com/astdys/index.php?pc=1.1.6&n=764 |access-date= 28 May 2020}}</ref>
<ref name="Zappala-family">{{cite journal |last1 = Zappalà |first1 = V. |last2 = Bendjoya |first2 = Ph. |last3 = Cellino |first3 = A. |last4 = Farinella |first4 = P. |last5 = Froeschle |first5 = C. |date = 1997 |title = Asteroid Dynamical Families |url = https://sbnarchive.psi.edu/pds3/non_mission/EAR_A_5_DDR_FAMILY_V4_1/data/family.tab |journal = NASA Planetary Data System |pages = EAR-A-5-DDR-FAMILY-V4.1 |access-date = 28 May 2020}} ([https://sbn.psi.edu/pds/resource/family.html PDS main page])</ref>
<ref name="Lazzaro-2004">{{Cite journal |first1 = D. |last1 = Lazzaro |first2 = C. A. |last2 = Angeli |first3 = J. M. |last3 = Carvano |first4 = T. |last4 = Mothé-Diniz |first5 = R. |last5 = Duffard |first6 = M. |last6 = Florczak |date = November 2004 |title = S3OS2: the visible spectroscopic survey of 820 asteroids |url = http://sirrah.troja.mff.cuni.cz/yarko-site/tmp/eos/NEW/spectral_type_figure/s3os2.pdf |journal = Icarus |volume = 172 |issue = 1 |pages = 179–220 |bibcode = 2004Icar..172..179L |doi = 10.1016/j.icarus.2004.06.006 |access-date= 28 May 2020}}</ref>
}} <!-- end of reflist -->
== External links == * [http://www.minorplanet.info/PHP/OneAsteroidInfo.php Lightcurve Database Query] (LCDB), at ''www.minorplanet.info'' * [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] – ''Geneva Observatory'', Raoul Behrend * [http://www.minorplanetcenter.net/iau/lists/NumberedMPs000001.html Discovery Circumstances: Numbered Minor Planets (1)-(5000)] – Minor Planet Center * {{AstDys|764}} * {{JPL small body}}
{{Minor planets navigator |763 Cupido |number=764 |765 Mattiaca}} {{Small Solar System bodies}} {{Authority control}}
{{DEFAULTSORT:Gedania}} 000764 Category:Discoveries by Franz Kaiser Category:Named minor planets 000764 19130926