{{Short description|Main-belt asteroid}} {{Use dmy dates|date=October 2019}} {{Infobox planet | minorplanet = yes | name = 19741 Callahan | background = #D6D6D6 | image = | image_size = | caption = | discovery_ref = <ref name="jpldata" /> | discovered = 5 January 2000 | discoverer = LINEAR | discovery_site = Lincoln Lab ETS | mpc_name = (19741) Callahan | alt_names = {{nowrap|{{mp|2000 AN|141}}{{·}}{{mp|1978 RQ|8}}}} | named_after = Diane Callahan<br />{{small|(mentor at DCYSC)}}<ref name="springer" /> | mp_category = main-belt<ref name="MPC-Callahan" />{{·}}{{small|(inner)}}<ref name="lcdb" /><br />background | orbit_ref = <ref name="jpldata" /> | epoch = 4 September 2017 (JD 2458000.5) | uncertainty = 0 | observation_arc = 38.66 yr (14,121 days) | aphelion = 2.5407 AU | perihelion = 1.9559 AU | semimajor = 2.2483 AU | eccentricity = 0.1301 | period = 3.37 yr (1,231 days) | mean_anomaly = 163.76° | mean_motion = {{Deg2DMS|0.2924|sup=ms}} / day | inclination = 8.0506° | asc_node = 167.39° | arg_peri = 227.28° | dimensions = 3.12 km {{small|(calculated)}}<ref name="lcdb" /><br />{{val|3.876|0.166}} km<ref name="WISE" /><ref name="Masiero-2011" /> | rotation = {{val|7.2684|0.0015}} h<ref name="Waszczak-2016" /> | albedo = 0.20 {{small|(assumed)}}<ref name="lcdb" /><br />{{val|0.224|0.044}}<ref name="WISE" /><ref name="Masiero-2011" /> | spectral_type = S<ref name="lcdb" /> | abs_magnitude = 14.3<ref name="WISE" />{{·}}14.4<ref name="jpldata" />{{·}}{{val|14.444|0.004}}<ref name="Waszczak-2016" />{{·}}14.89<ref name="lcdb" /> }}
'''19741 Callahan''' (provisional designation '''{{mp|2000 AN|141}}''') is a stony background asteroid from the inner regions of the asteroid belt, approximately 3.5 kilometers in diameter.
It was discovered on 5 January 2000, by the ''Lincoln Near-Earth Asteroid Research'', LINEAR, at the Lincoln Laboratory's Experimental Test Site, Socorro, New Mexico, and named after a mentor of the 2003 Discovery Channel Young Scientist Challenge.<ref name="springer" /><ref name="MPC-Callahan" />
== Orbit and classification ==
The S-type asteroid orbits the Sun in the inner main-belt at a distance of 2.0–2.5 AU once every 3 years and 4 months (1,231 days). Its orbit has an eccentricity of 0.13 and an inclination of 8° with respect to the ecliptic.<ref name="jpldata" /> Callahan was first identified as {{mp|1978 RQ8}} at ESO's La Silla Observatory in 1978, which extends the asteroid's observation arc by 22 years prior to its official discovery observation.<ref name="MPC-Callahan" />
== Physical characteristics ==
In December 2009, a rotational lightcurve for this asteroid was obtained from photometric observations at the U.S. Palomar Transient Factory, California. It gave a rotation period of {{val|7.2684|0.0015}} hours with a relatively high brightness variation of 0.81 in magnitude ({{small|U=2}}), indicative of a non-spherical shape.<ref name="Waszczak-2016" />
According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, ''Callahan'' measures 3.9 kilometers in diameter and its surface has an albedo of 0.22.<ref name="WISE" /> The ''Collaborative Asteroid Lightcurve Link'' assumes a standard albedo for stony asteroids of 0.20 and calculates a diameter of 3.1 kilometers, with an absolute magnitude of 14.89.<ref name="lcdb" />
== Naming ==
This minor planet was named after Diane Callahan, teacher at U.S. Fairfield Middle School, Ohio, who mentored a finalist in the 2003 ''Discovery Channel Youth Science Challenge'' (DCYSC), a middle school science competition.<ref name="springer" /> The approved naming citation was published by the Minor Planet Center on 10 October 2003 ({{small|M.P.C. 49772}}).<ref name="MPC-Circulars-Archive" />
== References == <references>
<ref name="jpldata">{{cite web |type = 2017-05-01 last obs. |title = JPL Small-Body Database Browser: 19741 Callahan (2000 AN141) |url = https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2019741 |publisher = Jet Propulsion Laboratory |access-date = 5 July 2017}}</ref>
<ref name="springer">{{cite book |title = Dictionary of Minor Planet Names – (19741) Callahan, Addendum to Fifth Edition: 2003–2005 |last = Schmadel | first = Lutz D. |publisher = Springer Berlin Heidelberg |page = 142 |date = 2006 |isbn = 978-3-540-34360-8 |doi = 10.1007/978-3-540-34361-5_1597 |chapter = (19741) Callahan [2.25, 0.13, 8.0] }}</ref>
<ref name="MPC-Callahan">{{cite web |title = 19741 Callahan (2000 AN141) |work = Minor Planet Center |url = https://www.minorplanetcenter.net/db_search/show_object?object_id=19741 |access-date = 22 March 2016}}</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 |access-date = 17 May 2016}}</ref>
<ref name="lcdb">{{cite LCDB|number = 19741 |access-date = 17 May 2016}}</ref>
<ref name="WISE">{{cite journal |display-authors = 6 |first1 = A. |last1 = Mainzer |first2 = T. |last2 = Grav |first3 = J. |last3 = Masiero |first4 = E. |last4 = Hand |first5 = J. |last5 = Bauer |first6 = D. |last6 = Tholen |first7 = R. S. |last7 = McMillan |first8 = T. |last8 = Spahr |first9 = R. M. |last9 = Cutri |first10 = E. |last10 = Wright |first11 = J. |last11 = Watkins |first12 = W. |last12 = Mo |first13 = C. |last13 = Maleszewski |date = November 2011 |title = NEOWISE Studies of Spectrophotometrically Classified Asteroids: Preliminary Results |url = http://adsabs.harvard.edu/cgi-bin/bib_query?bibcode=2011ApJ...741...90M |journal = The Astrophysical Journal |volume = 741 |issue = 2 |page = 25 |bibcode = 2011ApJ...741...90M |doi = 10.1088/0004-637X/741/2/90 |arxiv = 1109.6407 |access-date= 17 May 2016}}</ref>
<ref name="Waszczak-2016">{{cite journal |display-authors = 6 |first1 = Adam |last1 = Waszczak |first2 = Chan-Kao |last2 = Chang |first3 = Eran O. |last3 = Ofek |first4 = Russ |last4 = Laher |first5 = Frank |last5 = Masci |first6 = David |last6 = Levitan |first7 = Jason |last7 = Surace |first8 = Yu-Chi |last8 = Cheng |first9 = Wing-Huen |last9 = Ip |first10 = Daisuke |last10 = Kinoshita |first11 = George |last11 = Helou |first12 = Thomas A. |last12 = Prince |first13 = Shrinivas |last13 = Kulkarni |date = September 2015 |title = Asteroid Light Curves from the Palomar Transient Factory Survey: Rotation Periods and Phase Functions from Sparse Photometry |url = http://adsabs.harvard.edu/cgi-bin/bib_query?bibcode=2015AJ....150...75W |journal = The Astronomical Journal |volume = 150 |issue = 3 |page = 35 |bibcode = 2015AJ....150...75W |doi = 10.1088/0004-6256/150/3/75 |arxiv = 1504.04041 |access-date= 17 May 2016}}</ref>
<ref name="Masiero-2011">{{cite journal |display-authors = 6 |first1 = Joseph R. |last1 = Masiero |first2 = A. K. |last2 = Mainzer |first3 = T. |last3 = Grav |first4 = J. M. |last4 = Bauer |first5 = R. M. |last5 = Cutri |first6 = J. |last6 = Dailey |first7 = P. R. M. |last7 = Eisenhardt |first8 = R. S. |last8 = McMillan |first9 = T. B. |last9 = Spahr |first10 = M. F. |last10 = Skrutskie |first11 = D. |last11 = Tholen |first12 = R. G. |last12 = Walker |first13 = E. L. |last13 = Wright |first14 = E. |last14 = DeBaun |first15 = D. |last15 = Elsbury |first16 = T. IV |last16 = Gautier |first17 = S. |last17 = Gomillion |first18 = A. |last18 = Wilkins |date = November 2011 |title = Main Belt Asteroids with WISE/NEOWISE. I. Preliminary Albedos and Diameters |url = http://adsabs.harvard.edu/cgi-bin/bib_query?bibcode=2011ApJ...741...68M |journal = The Astrophysical Journal |volume = 741 |issue = 2 |page = 20 |bibcode = 2011ApJ...741...68M |doi = 10.1088/0004-637X/741/2/68 |arxiv = 1109.4096 |access-date= 3 December 2016}}</ref>
</references> <!-- end of reflist -->
== External links == * [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 }}) * [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] – Observatoire de Genève, Raoul Behrend * [https://www.minorplanetcenter.net/iau/lists/NumberedMPs015001.html Discovery Circumstances: Numbered Minor Planets (15001)-(20000)] – Minor Planet Center * {{AstDys|19741}} * {{JPL small body}}
{{Minor planets navigator | |number=19741 | }} {{Small Solar System bodies}} {{Authority control}}
{{DEFAULTSORT:Callahan}} 019741 019741 Category:Named minor planets 20000105