View source for 927 Ratisbona

{{Use dmy dates|date=February 2020}}
{{Infobox planet
| minorplanet     = yes
| name            = 927 Ratisbona
| background      = #D6D6D6
| image           =
| image_size      =
| caption         =
| discovery_ref   = &thinsp;<ref name="MPC-object" />
| discoverer      = [[Max Wolf|M. F. Wolf]]
| discovery_site  = [[Heidelberg-Königstuhl State Observatory|Heidelberg Obs.]]
| discovered      = 16 February 1920
| mpc_name        = (927) Ratisbona
| alt_names       = A920 DB{{·}}1920 GO<br />1958 VD{{·}}1958 XQ
| pronounced      = {{IPAc-en|r|æ|t|ᵻ|s|'|b|oʊ|n|ə}}<!--Latin stress assumed from TIS not being stressed in English 'Ratisbon'-->
| named_after     = [[Regensburg]]<br />{{small|(German city)}}<ref name="springer" />
| mp_category     = [[main-belt]]&thinsp;<ref name="MPC-object" />{{·}}{{small|([[Kirkwood gap|outer]])}}&thinsp;<ref name="jpldata" /><br />[[Background asteroid|background]]&thinsp;<ref name="AstDys-object" /><ref name="Ferret" />
| orbit_ref       = &thinsp;<ref name="jpldata" />
| epoch           = 31 May 2020 ([[Julian day|JD]] 2459000.5)
| uncertainty     = 0
| observation_arc = 99.57 [[Julian year (astronomy)|yr]] (36,368 d)
| aphelion        = 3.5095 [[Astronomical unit|AU]]
| perihelion      = 2.9476 AU
| semimajor       = 3.2285 AU
| eccentricity    = 0.0870
| period          = 5.80 yr (2,119 d)
| mean_anomaly    = 88.007[[Degree (angle)|°]]
| mean_motion     = {{Deg2DMS|0.1699|sup=ms}} / day
| inclination     = 14.572°
| asc_node        = 7.6887°
| arg_peri        = 171.36°
| mean_diameter   = {{plainlist|
* {{val|67.57|1.3|ul=km}}<ref name="SIMPS" />
* {{val|75.892|0.187|u=km}}<ref name="Masiero-2014" />
* {{val|78.20|1.11|u=km}}<ref name="AKARI" />}}
| rotation        = {{val|12.986|0.003|ul=h}}<ref name="lcdb" />
| albedo          = {{plainlist|
* {{val|0.044|0.002}}<ref name="AKARI" />
* {{val|0.046|0.004}}<ref name="Masiero-2014" />
* {{val|0.0591|0.002}}<ref name="SIMPS" />}}
| spectral_type   = {{plainlist|
* [[Tholen classification|Tholen]] {{=}} [[C-type asteroid|C]][[B-type asteroid|B]]:&thinsp;<ref name="jpldata" />
* [[Asteroid color indices|B–V]] {{=}} {{val|0.722|0.034}}<ref name="jpldata" />
* [[Asteroid color indices|U–B]] {{=}} {{val|0.401|0.036}}<ref name="jpldata" />
* {{nowrap|[[Asteroid color indices|V–R]] {{=}} {{val|0.407|0.016}}<ref name="Warner-2007" />}}}}
| abs_magnitude   = 9.3<ref name="MPC-object" /><ref name="jpldata" />
}}
'''927 Ratisbona''' is a large and dark [[background asteroid]], approximately {{convert|76|km|mi|abbr=off|sigfig=2|sp=us}} in diameter, located in the outer region of the [[asteroid belt]]. It was discovered on 16 February 1920, by astronomer [[Max Wolf]] at the [[Heidelberg Observatory]] in southwest Germany.<ref name="MPC-object" /> The carbonaceous [[C-type asteroid]] (CB) has a [[rotation period]] of 12.99 hours and is rather spherical in shape. It was named after the Bavarian city of [[Regensburg]].<ref name="springer" />
== Orbit and classification ==
''Ratisbona'' is a non-[[Asteroid family|family]] asteroid of the main belt's [[Background asteroid|background population]] when applying the [[hierarchical clustering method]] to its [[proper orbital elements]].<ref name="AstDys-object" /><ref name="Ferret" /> It orbits the Sun in the [[Kirkwood gap|outer]] asteroid belt at a distance of 2.9–3.5&nbsp;[[Astronomical unit|AU]] once every 5 years and 10 months (2,119 days; [[semi-major axis]] of 3.23&nbsp;AU). Its orbit has an [[orbital eccentricity|eccentricity]] of 0.09 and an [[orbital inclination|inclination]] of 15[[Degree (angle)|°]] with respect to the [[ecliptic]].<ref name="jpldata" /> The body's [[observation arc]] begins at [[Heidelberg-Königstuhl State Observatory]] on 17 February 1920, the night after its official discovery observation.<ref name="MPC-object" />
== Naming ==
This [[minor planet]] was named after the [[Latin language|Latin]] name of the German city of [[Regensburg]] in Bavaria, where astronomer [[Johannes Kepler]] died in 1630. The {{MoMP|927|naming}} was mentioned in the astronomical journal ''[[Astronomische Nachrichten]]'' in 1930 ({{small|[[Astronomische Nachrichten|AN]] 240, 135}}).<ref name="springer" />
== Physical characteristics ==
In the [[Tholen classification]], ''Ratisbona'' is most similar to a common, carbonaceous [[C-type asteroid]], and somewhat similar to a brighter [[B-type asteroid]], based on a nosy spectrum (CB:).<ref name="jpldata" /><ref name="Ferret" />
=== Rotation period ===
Over the course of seven nights in January 2018, a rotational [[lightcurve]] of ''Ratisbona'' was obtained from [[Photometry (astronomy)|photometric]] observations by [[Thomas A. Polakis|Tom Polakis]] at the Command Module Observatory {{Obscode|V02}} in Arizona. Lightcurve analysis gave a [[rotation period]] of {{val|12.986|0.003}} hours with a low brightness variation of {{val|0.15|0.02}} [[Magnitude (astronomy)|magnitude]], indicative of a regular, spherical shape ({{small|[[LCDB quality code|U=3-]]}}).<ref name="Polakis-2018" /> The result supersedes a period of {{val|12.9938|0.0007}} hours with an amplitude of {{val|0.12|0.01}} magnitude determined by [[René Roy (astronomer)|René Roy]], [[Raoul Behrend]], [[Pierre Antonini]] and Donn Starkey in October 2004 ({{small|[[LCDB quality code|U=2]]}}).<ref name="geneva-obs" />
=== Diameter and albedo ===
According to the survey carried out by the Infrared Astronomical Satellite [[IRAS]], the [[NEOWISE]] mission of NASA's [[Wide-field Infrared Survey Explorer]] (WISE), and the Japanese [[Akari (satellite)|Akari satellite]], ''Ratisbona'' measures ({{val|67.57|1.3}}), ({{val|75.892|0.187}}) and ({{val|78.20|1.11}}) kilometers in diameter and its surface has a very low [[astronomical albedo|albedo]] of ({{val|0.0591|0.002}}), ({{val|0.046|0.004}}) and ({{val|0.044|0.002}}), respectively.<ref name="SIMPS" /><ref name="Masiero-2014" /><ref name="AKARI" />
The ''Collaborative Asteroid Lightcurve Link'' adopts the results from IRAS, that is, a albedo of 0.0591 and a diameter of 67.57&nbsp;km based on an [[absolute magnitude]] of 9.54.<ref name="lcdb" /> Further published mean-diameters and albedos by the WISE team include ({{val|73.204|1.485|u=km}}) and ({{val|84.872|1.352|u=km}}) and albedos of ({{val|0.050|0.011}}) and ({{val|0.0375|0.0027}}).<ref name="Ferret" /><ref name="lcdb" /> An [[asteroid occultation]], observed on 13 September 2014, gave a best-fit ellipse dimension of 78.0&thinsp;×&thinsp;78.0 kilometers.<ref name="Ferret" /> These timed observations are taken when the asteroid passes in front of a distant star. However the quality of the measurement is rated poorly.<ref name="Ferret" />
== References ==
{{reflist|30em|refs=
<ref name="jpldata">{{cite web
|type       = 2019-09-13 last obs.
|title      = JPL Small-Body Database Browser: 927 Ratisbona (A920 DB)
|url        = https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2000927
|publisher  = [[Jet Propulsion Laboratory]]
|access-date = 20 February 2020}}</ref>
<ref name="springer">{{cite book
|title      = Dictionary of Minor Planet Names
|url      = https://archive.org/details/dictionaryminorp00schm
|url-access = limited
|last       = Schmadel | first = Lutz D.
|publisher  = Springer Berlin Heidelberg
|chapter    = (927) Ratisbona
|page       = [https://archive.org/details/dictionaryminorp00schm/page/n95 82]
|date       = 2007
|doi        = 10.1007/978-3-540-29925-7_928
|isbn       = 978-3-540-00238-3}}</ref>
<ref name="MPC-object">{{cite web
|title      = 927 Ratisbona (A920 DB)
|work       = Minor Planet Center
|url        = https://www.minorplanetcenter.net/db_search/show_object?object_id=927
|access-date = 20 February 2020}}</ref>
<ref name="geneva-obs">{{cite web
|title      = Asteroids and comets rotation curves – (927) Ratisbona
|last       = Behrend |first = Raoul
|publisher  = [[Geneva Observatory]]
|url        = http://obswww.unige.ch/~behrend/page3cou.html#000927
|access-date = 20 February 2020}}</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
|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}}</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=927 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 = 18 February 2020}}</ref>
<ref name="lcdb">{{cite web
|title      = LCDB Data for (927) Ratisbona
|publisher  = Asteroid Lightcurve Database (LCDB)
|url        = http://www.minorplanet.info/PHP/generateOneAsteroidInfo.php?AstInfo=927
|access-date = 20 February 2020}}</ref>
<ref name="Polakis-2018">{{cite journal
|last1        = Polakis
|first1       = Tom
|date         = July 2018
|title        = Lightcurve Analysis for Eleven Main-belt Asteroids
|journal      = Minor Planet Bulletin
|url          = http://www.minorplanet.info/MPB/issues/MPB_45-3.pdf
|volume       = 45
|issue        = 3
|pages        = 269–273
|bibcode      = 2018MPBu...45..269P
|issn         = 1052-8091
|access-date  = 20 February 2020
|archive-date = 13 April 2019
|archive-url  = https://web.archive.org/web/20190413235907/http://www.minorplanet.info/MPB/issues/MPB_45-3.pdf
|url-status   = dead
}}</ref>
<ref name="Warner-2007">{{cite journal
|last1        = Warner
|first1       = Brian D.
|date         = December 2007
|title        = Initial Results of a Dedicated H-G Project
|journal      = Minor Planet Bulletin
|url          = http://www.minorplanet.info/MPB/issues/MPB_34-4.pdf
|volume       = 34
|issue        = 4
|pages        = 113–119
|bibcode      = 2007MPBu...34..113W
|issn         = 1052-8091
|access-date  = 20 February 2020
|archive-date = 20 February 2020
|archive-url  = https://web.archive.org/web/20200220161709/http://www.minorplanet.info/MPB/issues/MPB_34-4.pdf
|url-status   = dead
}}</ref>
<ref name="Ferret">{{cite web
|title      = Asteroid 927 Ratisbona
|work       = Small Bodies Data Ferret
|url        = https://sbntools.psi.edu/ferret/SimpleSearch/results.action?targetName=927+Ratisbona
|access-date = 20 February 2020}}</ref>
<ref name="AstDys-object">{{cite web
|title      = Asteroid 927 Ratisbona – Proper Elements
|publisher  = AstDyS-2, Asteroids – Dynamic Site
|url        = https://newton.spacedys.com/astdys/index.php?pc=1.1.6&n=927
|access-date= 20 February 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|927}}
* {{JPL small body}}
{{Minor planets navigator |926 Imhilde |number=927 |928 Hildrun}}
{{Small Solar System bodies}}
{{Authority control}}
{{DEFAULTSORT:Ratisbona}}
[[Category:Background asteroids|000927]]
[[Category:Discoveries by Max Wolf]]
[[Category:Named minor planets]]
[[Category:CB:-type asteroids (Tholen)|000927]]
[[Category:Astronomical objects discovered in 1920|19200216]]