View source for 210P/Christensen

{{Infobox comet
| name           = 210P/Christensen
| image          = SECCHI Makes a Fantastic Recovery - Hi1-B p2003k2 panel.jpg
| caption        = The recovery image of the comet by STEREO, on 13 December 2008
| discovery_ref  = <ref name="IAUC 8136">{{cite web |first= Daniel |last= Green |title=IAUC 8136: C/2003 K2; 2003ej, 2003ek,, 2003el |url= http://www.cbat.eps.harvard.edu/iauc/08100/08136.html |website=www.cbat.eps.harvard.edu |date= 27 May 2003 |access-date=12 December 2023}}</ref>
| discoverer     = [[Eric J. Christensen]]
| discoverery_site = 
| discovery_date = 26 May 2003
| mpc_name       = <!--(Minor Planet Center's designation)-->
| designations   = P/2003 K2, P/2008 X4
| orbit_ref      = <ref name="jpl">{{cite web |title=Small-Body Database Lookup: 210P/IRAS |url=https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=210P |website=ssd.jpl.nasa.gov |access-date=20 July 2023}}</ref>
| epoch          = 3 February 2010
| observation_arc =
| earliest_precovery_date =
| obs            =
| orbit          =
| aphelion       = 5.817 AU
| perihelion     = 0.534 AU
| semimajor      = 3.176 AU
| semiminor      = 
| orbital_circ   = 
| eccentricity   = 0.8317
| period         = 5.659 years
| avg_speed      = 
| max_speed      = 
| min_speed      = 
| inclination    = 10.217°
| asc_node       = 93.872°
| arg_peri       = 345.766°
| long_peri      =
| tjup           = 2.492
| Earth_moid     = 0.170 AU
| Jupiter_moid   = 0.018 AU
| physical_ref   = 
| dimensions     = ≤ 1.74 km<ref name="Fernández-Sosa">{{cite journal |last1=Fernández |first1=Julio A. |last2=Sosa |first2=Andrea |title=Jupiter family comets in near-Earth orbits: Are some of them interlopers from the asteroid belt? |journal=Planetary and Space Science |date=1 December 2015 |volume=118 |pages=14–24 |doi=10.1016/j.pss.2015.07.010|bibcode=2015P&SS..118...14F }}</ref>
| sidereal_day   = 
| rot_velocity   = <!--(Rotational velocity)-->
| rotation       = <!--(Rotation period)-->
| albedo         = 
| spectral_type  = <!--asteroid spectral class, color indices, etc.-->
| M1             = 14.9<ref name="jpl"/>
| M2             = 
| magnitude      = <!--apparent magnitude-->
| last_p         = 7 April 2020
| next_p         = 22 November 2025 <ref>{{cite web |title=210P/Christensen |url=http://www.aerith.net/comet/catalog/0210P/index.html |website=www.aerith.net |access-date=12 December 2023}}</ref>
| b_semimajor    = <!--barycentric semimajor axis, generally used only for long-period or hyperbolic comets -->
| b_period       = 
}}

'''210P/Christensen''' is a [[Jupiter family comet|Jupiter family]] [[periodic comet]] with an [[orbital period]] of 5.7 years. It was discovered by [[Eric J. Christensen]] on 26 May 2003 in images taken by the [[Catalina Sky Survey]]<ref name="IAUC 8136"/> and recovered in images obtained by [[STEREO]], the first time a single-apparition comet was recovered by a spacecraft.<ref name="Stereorecovery">{{cite web |title=SECCHI Makes a Fantastic Recovery! |url=https://stereo.gsfc.nasa.gov/gallery/item.shtml?id=stereoimages&iid=85 |website=stereo.gsfc.nasa.gov |publisher=NASA |date= 17 December 2008 |access-date=12 December 2023}}</ref>

[[Eric J. Christensen]] discovered the comet on 26 May 2003 in images taken with the 0.7-m [[Schmidt telescope]] of the [[Catalina Sky Survey]]. The comet had an estimated magnitude of 14.6 and a coma with an estimated diameter between 10 and 35 arcseconds and a faint tail.<ref name="IAUC 8136"/> Further observations revealed the comet had a short [[orbital period]].<ref>{{cite web |first= Daniel |last= Green |title=IAUC 8145: C/2003 L1; P/2003 K2; C/2003 K4 |url=http://www.cbat.eps.harvard.edu/iauc/08100/08145.html |website=www.cbat.eps.harvard.edu |date= 7 June 2003 |access-date=12 December 2023}}</ref>

In mid December 2008, Australian comet-hunter Alan Watson spotted in the STEREO/SECCHI Heliospheric Imager ("HI") HI-1B data a cometary object. Veteran German comet hunter Rainer Kracht recorded a few positions of the comet in the data and produced a set of very approximate orbital elements for it.<ref name="Stereorecovery"/> Maik Meyer noticed the similarity of these orbital elements to those of P/2003 K2 and the link was confirmed by [[Brian G. Marsden|Brian Marsden]].<ref name="Stereorecovery"/><ref>{{cite journal |last1=Battams |first1=K. |last2=Watson |first2=A. |last3=Kracht |first3=R. |last4=Meyer |first4=M. |last5=Marsden |first5=B. G. |title=Comet P/2008 X4 = P/2003 K2 (Christensen) |journal=International Astronomical Union Circular |date=1 December 2008 |issue=9005 |pages=1 |bibcode=2008IAUC.9005....1B |url=https://ui.adsabs.harvard.edu/abs/2008IAUC.9005....1B/abstract |issn=0081-0304}}</ref> This was the first recovery by a spacecraft of a single-apparition comet (a comet that had only been observed to pass the Sun once) by a spacecraft.<ref name="Stereorecovery"/> The comet was observed from the ground on 31 November 2008, with an estimated magnitude of 11.<ref>{{cite journal |last1=Kadota |first1=K. |last2=Marsden |first2=B. G. |title=Comet P/2008 X4 (Christensen) |journal=International Astronomical Union Circular |date=1 January 2009 |issue=9008 |pages=2 |bibcode=2009IAUC.9008....2K |url=https://ui.adsabs.harvard.edu/abs/2009IAUC.9008....2K/abstract |issn=0081-0304}}</ref>

The comet has been locked in a 2:1 [[orbital resonance]] with [[Jupiter (planet)|Jupiter]] for the last 10,000 years and could be of asteroidal origin.<ref name="Fernández-Sosa"/>

== References ==
{{reflist}}

== External links ==
* {{JPL small body|id=1000440}}

{{PeriodicComets Navigator|209P/LINEAR|211P/Hill}}
{{Comets}}

{{DEFAULTSORT:210P Christensen}}
[[Category:Jupiter-family comets]]
[[Category:Near-Earth comets]]
[[Category:Numbered comets|0210]]
[[Category:Discoveries by Eric J. Christensen]]