View source for 121P/Shoemaker–Holt

{{Short description|Periodic comet with an eight-year orbit}}
{{For|other comets discovered by Carolyn and Eugene Shoemaker|Comet Shoemaker}}
{{Infobox comet
| name=121P/Shoemaker-Holt
| image= 121P 2006-08-01 Spitzer image Level-2-PBCD-MIPS-24um.png
| discoverer=[[Carolyn S. Shoemaker]]<br />[[Eugene Merle Shoemaker]]<br />[[Henry E. Holt]]
| discovery_date=March 9, 1989
| designations=1989j; 1988 XI; 1995 Q3
| epoch=March 6, 2006
| semimajor=4.013 [[Astronomical Unit|AU]]
| perihelion=2.65 AU
| aphelion=5.376 AU
| eccentricity=0.3396
| period=8.039 [[Julian year (astronomy)|a]]
| inclination= 17.7218°
| physical_ref  = {{r|Snodgrass_2008|Fernández_2013|Knight_2023}}
| mean_radius   = {{cvt|3.61|km|mi}}
| rotation      = ~10 hours
| spectral_type = (V–R) {{=}} {{val|0.53|0.03}}
| last_p=September 8, 2013<ref name="NK1925">{{cite web
  |date=2010-04-28
  |title=121P/Shoemaker-Holt 2 (NK 1925)
  |publisher=OAA Computing and Minor Planet Sections
  |author=Syuichi Nakano
  |author-link=Syuichi Nakano
  |url=http://www.oaa.gr.jp/~oaacs/nk/nk1925.htm
  |accessdate=2012-02-25}}</ref><br />September 1, 2004
| next_p=2023-Jun-28<ref name=MPC>{{cite web
  |title=121P/Shoemaker-Holt Orbit
  |url=http://www.minorplanetcenter.net/db_search/show_object?object_id=121P
  |publisher=[[Minor Planet Center]]
  |accessdate=2014-06-17}}</ref>
}}

'''121P/Shoemaker–Holt''', also known as '''Shoemaker-Holt 2''', is a [[List of periodic comets|periodic]] [[comet]] in the [[Solar System]] with an orbital period of about 8 years. The comet was discovered by [[Carolyn S. Shoemaker]], [[Eugene M. Shoemaker]], and [[Henry E. Holt]] on 9 March 1989. The comet then had an apparent magnitude of 13, was diffuse and had a tail about 2 arcminutes long.<ref>{{cite journal |last1=Green |first1=Daniel |title=IAUC 4755: 1989j; U Gem; 1989B; N Vul 1987 |website=www.cbat.eps.harvard.edu |date=10 March 1989 |url=http://www.cbat.eps.harvard.edu/iauc/04700/04755.html}}</ref> It was recovered by [[James V. Scotti]] on 29 August 1995 in images obtained as part of the [[Spacewatch]] survey.<ref>{{cite journal |last1=Scotti |first1=J. V. |last2=Green |first2=D. W. E. |last3=Marsden |first3=B. G. |title=Comet P/1995 Q3 (Shoemaker-Holt 2) |journal=International Astronomical Union Circular |date=1 September 1995 |issue=6219 |pages=2 |bibcode=1995IAUC.6219....2S |url=http://www.cbat.eps.harvard.edu/iauc/06200/06219.html#Item2 |issn=0081-0304}}</ref>

The nucleus of the comet is estimated to have a radius of 3.87 km based on infrared imaging by the [[Spitzer Space Telescope]], when the comet displayed dust emission.{{r|Fernández_2013}} Observations of the comet from the Isaac Newton Telescope indicate an effective radius of 3.61 kilometers. The rotational period was calculated to be 10 hours, but with high uncertainty.{{r|Snodgrass_2008}}

== References ==
{{Reflist|refs=

<ref name="Fernández_2013">{{cite journal
| author1= Y. R. Fernández
| author2= M. S. P. Kelley
| author3= P. L. Lamy
| author4= I. Toth
| author5= O. Groussin
| author6= C. M. Lisse
| author7= M. F. A’Hearn
| author8= J. M. Bauer
| author9= H. Campins
| author10= A. Fitzsimmons
| author11= J. Licandro
| author12= S. C. Lowry
| author13= K. J. Meech
| author14= J. Pittichová
| author15= W. T. Reach
| author16= C. Snodgrass
| author17= H. A. Weaver
| display-authors= 5
| title= Thermal properties, sizes, and size distribution of Jupiter-family cometary nuclei
| journal= [[Icarus (journal)|Icarus]]
| year= 2013
| volume= 226
| issue= 1
| pages= 1138–1170
| bibcode= 2013Icar..226.1138F
| arxiv= 1307.6191
| doi= 10.1016/j.icarus.2013.07.021 }}
</ref>

<ref name="Knight_2023">{{cite arXiv
| author1= M. M. Knight
| author2= R. Kokotanekova
| author3= N. H. Samarasinha
| title= Physical and Surface Properties of Comet Nuclei from Remote Observations
| year= 2023
| eprint= 2304.09309
| class= astro-ph.EP }}
</ref>

<ref name="Snodgrass_2008">{{cite journal
| author1= C. Snodgrass
| author2= S. C. Lowry
| author3= A. Fitzsimmons
| title= Optical observations of 23 distant Jupiter Family Comets, including 36P/Whipple at multiple phase angles
| journal= Monthly Notices of the Royal Astronomical Society 
| year= 2008
| volume= 385
| issue= 2
| pages= 737–756
| bibcode= 2008MNRAS.385..737S
| arxiv= 0712.4204
| doi= 10.1111/j.1365-2966.2008.12900.x
| doi-access= free }}
</ref>

}}

== External links ==
* [http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=121P;orb=1 Orbital simulation] from JPL (Java) / [http://ssd.jpl.nasa.gov/horizons.cgi?find_body=1&body_group=sb&sstr=121P Horizons Ephemeris]
* [http://www.aerith.net/comet/catalog/0121P/index.html 121P/Shoemaker-Holt 2] – Seiichi Yoshida @ aerith.net
*[http://cometography.com/pcomets/121p.html 121P at Kronk's Cometography]

{{PeriodicComets Navigator|120P/Mueller|122P/de Vico}}
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{{DEFAULTSORT:Shoemaker, 121P}}
[[Category:Periodic comets]]
[[Category:Numbered comets|0121]]
[[Category:Discoveries by Carolyn S. Shoemaker|121P]]
[[Category:Discoveries by Eugene Merle Shoemaker|121P]]
[[Category:Discoveries by Henry E. Holt|121P]]
[[Category:Comets in 2013|121P]]
[[Category:Astronomical objects discovered in 1989|19890309]]


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