View source for (505657) 2014 SR339

{{Short description|Asteroid of the Apollo group}}
{{DISPLAYTITLE:{{mp|(505657) 2014 SR|339}}}}
{{Use dmy dates|date=March 2018}}
{{Infobox planet
 | minorplanet     = yes
 | name            = (505657) {{mp|2014 SR|339}}
 | background      = #FFC2E0
 | image           = 2014 SR339 Arecibo.jpg
 | image_scale      =
 | caption         = Radar images of {{mp|2014 SR|339}} taken by the [[Arecibo Observatory]] on 9 February 2018
 | discovery_ref   = <ref name="MPC-object" />
 | discoverer      = [[Wide-field Infrared Survey Explorer|WISE]]
 | discovery_site  = ''Earth orbit''
 | discovered      = 30 September 2014
 | mpc_name        = (505657) {{mp|2014 SR|339}}
 | alt_names       = {{mp|2014 SR|339}}
 | pronounced      = 
 | named_after     = <!-- [[xafter]] {{small|(description)}}<ref name="MPC-object" />-->
 | mp_category     = {{nowrap|[[Apollo asteroid|Apollo]]{{·}}[[Near-Earth object|NEO]]{{·}}[[Potentially hazardous object|PHA]]<ref name="MPC-object" /><ref name="jpldata" />}}
 | orbit_ref       = <ref name="jpldata" />
 | epoch           = 23 March 2018 ([[Julian day|JD]] 2458200.5)
 | uncertainty     = 0
 | observation_arc = 3.41 [[Julian year (astronomy)|yr]] (1,245 d)
 | aphelion        = 1.6948 [[Astronomical unit|AU]]
 | perihelion      = 0.9046 AU
 | semimajor       = 1.2997 AU
 | eccentricity    = 0.3040
 | period          = 1.48 yr (541 d)
 | mean_anomaly    = 60.524[[Degree (angle)|°]]
 | mean_motion     = {{Deg2DMS|0.6652|sup=ms}} / day
 | inclination     = 29.790°
 | asc_node        = 138.78°
 | arg_peri        = 299.60°
 | moid            = {{convert|0.0354|AU|LD|lk=on|abbr=on|sigfig=3}}
 | dimensions      = (&gt;1.5 km × ?&nbsp;km)<ref name="Arecibo-and-Warner" />
 | mean_diameter   = {{val|0.971|0.367}} km<ref name="Nugent-2015" />
 | rotation        = {{val|8|-|9|ul=h}}<ref name="Arecibo-Twitter" /><br />8.729 h<ref name="Arecibo-and-Warner" />{{efn|name=lightcurve-plot-Warner}}
 | albedo          = {{val|0.068|0.074}}<ref name="Nugent-2015" />
 | spectral_type   = [[C-type asteroid|C]]{{small|(assumed on albeo)}}
 | abs_magnitude   = 18.6<ref name="jpldata" />
}}

'''{{mp|(505657) 2014 SR|339}}''', provisional designation {{mp|2014 SR|339}}, is a dark and elongated [[asteroid]], classified as [[near-Earth object]] and [[potentially hazardous asteroid]] of the [[Apollo asteroid|Apollo group]], approximately {{convert|970|m|ft|abbr=off|sigfig=2|sp=us}} in diameter. It was discovered on 30 September 2014, by NASA's [[Wide-field Infrared Survey Explorer]] telescope (WISE) in Earth's orbit.<ref name="MPC-object" /> Closely observed at [[Goldstone Deep Space Communications Complex|Goldstone]] and [[Arecibo Observatory|Arecibo]] in February 2018, it has a rotation period of 8.7 hours.<ref name="Arecibo-Twitter" />

== Orbit and classification ==

{{mp|2014 SR|339}} is a member of the [[Apollo asteroid]]s, which [[List of Earth-crossing minor planets|cross the orbit of Earth]]. Apollo's are the largest group of [[near-Earth objects]] with nearly 10 thousand known objects. It orbits the Sun at a distance of 0.90–1.70&nbsp;[[Astronomical unit|AU]] once every 18 months (541 days; [[semi-major axis]] of 1.30&nbsp;AU). Its orbit has an [[orbital eccentricity|eccentricity]] of 0.30 and an [[orbital inclination|inclination]] of 30[[Degree (angle)|°]] with respect to the [[ecliptic]].<ref name="jpldata" /> With an [[aphelion]] of 1.70&nbsp;AU, it is also a [[Mars-crosser]], as it crosses the orbit of the Red Planet at 1.666&nbsp;AU. The body's [[observation arc]] begins with its official discovery observation by WISE in September 2014.<ref name="MPC-object" />

=== Close approaches ===

As a [[potentially hazardous asteroid]], {{mp|2014 SR|339}} has a [[minimum orbital intersection distance]] (MOID) with Earth of less than 0.05&nbsp;AU and a diameter of greater than 150 meters. The Earth-MOID is currently {{convert |0.0354 |AU |km |abbr=on |lk=off |sigfig=3}}, which translates into 13.8 [[Lunar distance (astronomy)|lunar distances]] (LD).<ref name="jpldata" />

=== 2018 flyby===

On 7 February 2018 it passed {{convert|0.054|AU|LD|lk=on|abbr=on|sigfig=2}} from the Earth when its [[apparent magnitude]] brightened to 14.<ref name="Arecibo-and-Warner" /> [[Goldstone Deep Space Communications Complex|Goldstone]] observed it until the following day.<ref name="Goldstone" /> While this was an 8.1-million kilometer flyby, the next close flyby of 6.3 million km will occur on 5 February 2058, and another 7.6 million km on 8 February 2095. It will also have a 3.2 million km flyby of Mars on 26 September 2048.<ref name="AsteroidsNear" />

== Physical characteristics ==

The asteroid's [[Asteroid spectral type|spectral type]] is unknown. Due to its unusually low albedo ''(see below)'' it is likely a carbonaceous [[C-type asteroid]].<ref name="jpldata" />

=== Rotation period ===

On 9 February, radiometric observations by the [[Arecibo Observatory]] revealed that the asteroid has an elongated, lumpy shape.<ref name="Arecibo-and-Warner" /> The radar images also gave it a [[rotational period]] between 8 and 9 hours.<ref name="Arecibo-Twitter" /> A refined period of 8.7 hour agrees with (photometric) [[lightcurve]] observations by American photometrist [[Brian D. Warner|Brian Warner]] at the Center for Solar System Studies ({{small|[[IAU code#U82|U82]]}}) during 9–11 February 2018, who obtained a period of 8.729 hours with a high brightness amplitude of 0.93 [[Magnitude (astronomy)|magnitude]], which also indicates a non-spheroidal shape ({{small|[[LCDB quality code|U=3-]]}}).<ref name="Arecibo-and-Warner" />{{efn|name=lightcurve-plot-Warner}}

=== Diameter and albedo ===

According to the survey carried out by the [[NEOWISE]] mission of NASA's WISE telescope, {{mp|2014 SR|339}} measures 0.971 kilometers in diameter and its surface has an [[astronomical albedo|albedo]] of 0.068.<ref name="Nugent-2015" /> During its close approach in February 2018, radiometric observations by Arecibo Observatory determined that the object is at least {{convert|1.5|km|mi|abbr=off|sp=us}} wide.<ref name="Arecibo-and-Warner" /> Data from the [[Arecibo Telescope]] released in 2022 showed an unusually high radar albedo, possibly indicating rich metal content.<ref>{{citation|work=[[Sky & Telescope]]|title=ARECIBO LEGACY: NEW DATA ON NEAR-EARTH ASTEROIDS|author=Colin Stuart|date=November 1, 2022|url=https://skyandtelescope.org/astronomy-news/arecibos-legacy-new-data-on-near-earth-asteroid/}}</ref>

== Numbering and naming ==

This [[minor planet]] was numbered by the [[Minor Planet Center]] on 4 November 2017 ({{small|[[Minor Planet Circulars|M.P.C.]] 107069}}).<ref name="MPC-Circulars-Archive" /> As of 2018, it has not been [[List of named minor planets (alphabetical)|named]].<ref name="MPC-object" />

== Gallery ==
<gallery>
File:2014_SR339_skyview2018.png|Daily motion of asteroid across sky
File:2014_SR339_flyby2018.png|View of flyby above the earth and moon
</gallery>

== Notes ==
{{notelist|refs=

{{efn|name=lightcurve-plot-Warner|1=[http://www.planetarysciences.org/plots/BDW/505657_2014SR339_20180209.PNG lightcurve plot of (505657) 2014 SR339]: rotation period {{val|8.729|0.002}} hours with a brightness amplitude of {{val|0.93}} mag. Quality code of 3-. Summary figures at the [http://planetarysciences.org/ Center for Solar System Studies] (CS3)}}

}} <!-- end of notelist -->

== References==
{{reflist|refs=

<ref name="jpldata">{{cite web
  |type       = 2018-02-26 last obs.
  |title      = JPL Small-Body Database Browser: 505657 (2014 SR339)
  |url        = https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2505657
  |publisher  = [[Jet Propulsion Laboratory]]
  |accessdate = 5 March 2018}}</ref>

<ref name="MPC-object">{{cite web
  |title      = 505657 (2014 SR339)
  |work       = Minor Planet Center
  |url        = https://www.minorplanetcenter.net/db_search/show_object?object_id=505657
  |accessdate = 5 March 2018}}</ref>

<ref name="MPC-Circulars-Archive">{{cite web
  |title      = MPC/MPO/MPS Archive
  |work       = Minor Planet Center
  |url        = https://www.minorplanetcenter.net/iau/ECS/MPCArchive/MPCArchive_TBL.html
  |accessdate = 5 March 2018}}</ref>

<ref name="Nugent-2015">{{cite journal
  |display-authors = 6
  |first1     = C. R. |last1 = Nugent
  |first2     = A. |last2 = Mainzer
  |first3     = J. |last3 = Masiero
  |first4     = J. |last4 = Bauer
  |first5     = R. M. |last5 = Cutri
  |first6     = T. |last6 = Grav
  |first7     = E. |last7 = Kramer
  |first8     = S. |last8 = Sonnett
  |first9     = R. |last9 = Stevenson
  |first10    = E. L. |last10 = Wright
  |date       = December 2015
  |title      = NEOWISE Reactivation Mission Year One: Preliminary Asteroid Diameters and Albedos
  |journal    = The Astrophysical Journal
  |volume     = 814
  |issue      = 2
  |page       = 13
  |bibcode    = 2015ApJ...814..117N
  |doi        = 10.1088/0004-637X/814/2/117
  |arxiv      = 1509.02522|s2cid = 9341381 }}</ref>

<ref name="Goldstone">{{cite web
  |title      = Goldstone Radar Observations Planning: Asteroids 2002 AJ129, 2014 SR339, 2015 BN509, and 2018 CB
  |url        = https://echo.jpl.nasa.gov/asteroids/2002AJ129/2002AJ129_planning.2018.html
  |publisher  = Lance Benner – NASA/JPL
  |accessdate = 5 March 2018}}</ref>

<ref name="Arecibo-Twitter">{{cite web
  |quote      = Recent radar images of near-Earth asteroid (505657) 2014 SR339 from @NAICobservatory show a lumpy, elongated body at least 1.5 km long and rotating once every 8 to 9 hours!
  |title      = Recent radar images of (505657) 2014 SR339
  |url        = https://twitter.com/AreciboRadar/status/963448575312228352
  |publisher  = Twitter
  |accessdate = 5 March 2018}}</ref>

<ref name="AsteroidsNear">{{cite web
  |title      = Asteroid 505657 2014 SR339
  |url        = https://www.asteroidsnear.com/asteroid-505657-2014-sr339-4429
  |publisher  = asteroidsnear.com
  |accessdate = 5 March 2018}}</ref>

<ref name="Arecibo-and-Warner">{{cite web
  |title      = Near-Earth asteroid (505657) 2014 SR339
  |url        = http://outreach.naic.edu/ao/blog/near-earth-asteroid-505657-2014-sr339
  |date       = 14 February 2018
  |publisher  = Arecibo Observatory – NASA/JPL
  |accessdate = 5 March 2018}}</ref>

}} <!-- end of reflist -->

== External links ==
{{Commons category|(505657) 2014 SR339}}
* [https://www.minorplanetcenter.net/iau/lists/t_phas.html List of the Potentially Hazardous Asteroids (PHAs)], ''Minor Planet Center''
* [https://www.minorplanetcenter.net/iau/lists/t_apollos.html List Of Apollo Minor Planets (by designation)], ''Minor Planet''
* [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 }})
* {{NeoDys|505657}}
* {{ESA-SSA|505657|2014SR339}}
* {{JPL small body|id=2505657}}

{{2018 in space}}
{{Minor planets navigator | |number=505657 |PageName={{mp|(505657) 2014 SR|339}} | }}
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{{DEFAULTSORT:2014 SR339}}
[[Category:Apollo asteroids|505657]]
[[Category:Discoveries by WISE|505657]]
[[Category:Potentially hazardous asteroids|505657]]
[[Category:Near-Earth objects in 2018]]
[[Category:Astronomical objects discovered in 2014|20140930]]