{{Short description|Main-belt asteroid}} {{Use dmy dates|date=October 2019}} {{Infobox planet | minorplanet = yes | name = 7784 Watterson | background = #D6D6D6 | image = | image_size = | caption = | discovery_ref = <ref name="jpldata" /> | discovered = 5 August 1994 | discoverer = T. B. Spahr | discovery_site = Catalina Stn. | mpc_name = (7784) Watterson | alt_names = 1994 PL | named_after = Bill Watterson<br />{{small|(cartoonist)}}<ref name="MPC-Watterson" /> | mp_category = main-belt{{·}}Phocaea<ref name="lcdb" /><ref name="Ferret" /> | orbit_ref = <ref name="jpldata" /> | epoch = 4 September 2017 (JD 2458000.5) | uncertainty = 0 | observation_arc = 63.56 yr (23,217 days) | aphelion = 2.8025 AU | perihelion = 1.7348 AU | semimajor = 2.2686 AU | eccentricity = 0.2353 | period = 3.42 yr (1,248 days) | mean_anomaly = 280.49° | inclination = 23.350° | asc_node = 220.66° | arg_peri = 107.04° | dimensions = 5.53 km {{small|(calculated)}}<ref name="lcdb" /><br />{{val|5.556|0.070}} km<ref name="WISE" /><ref name="Masiero-2011" /> | rotation = {{val|2.539|0.001}} h{{efn|name=lcdb-Skiff}} | albedo = {{val|0.189|0.022}}<ref name="WISE" /><ref name="Masiero-2011" /><br />0.23 {{small|(assumed)}}<ref name="lcdb" /> | spectral_type = S<ref name="lcdb" /> | abs_magnitude = 13.5<ref name="jpldata" /><ref name="lcdb" />{{·}}13.7<ref name="WISE" /> }}
'''7784 Watterson''', provisional designation {{mp|1994 PL}}, is a stony Phocaea asteroid from the inner regions of the asteroid belt, approximately 6 kilometers in diameter. It was discovered by American astronomer Timothy Spahr at the U.S. Catalina Station, Arizona, on 5 August 1994.<ref name="MPC-Watterson" /> The asteroid was named after cartoonist Bill Watterson.<ref name="MPC-Watterson" />
== Orbit and classification ==
The S-type asteroid is a member of the Phocaea family ({{small|701}}),<ref name="Ferret" /> a group of asteroids with similar orbital characteristics. It orbits the Sun in the inner main-belt at a distance of 1.7–2.8 AU once every 3 years and 5 months (1,248 days). Its orbit has an eccentricity of 0.24 and an inclination of 23° with respect to the ecliptic.<ref name="jpldata" />
== Physical characteristics ==
In 2011, a photometric lightcurve analysis by astronomer Brian Skiff gave a rotation period of {{val|2.539}} hours with a relatively low brightness amplitude of 0.10 magnitude, indicative of a nearly spheroidal shape ({{small|U=3-}}).{{efn|name=lcdb-Skiff}}
According to the surveys carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer (WISE), ''Watterson'' has an albedo of 0.19 and a diameter of 5.6 kilometers.<ref name="WISE" /> The ''Collaborative Asteroid Lightcurve Link'' agrees with WISE's observations and assumes a slightly higher albedo of 0.23 and calculates a diameter of 5.5 kilometers.<ref name="lcdb" />
== Naming ==
This minor planet is named after Bill Watterson (born 1958), cartoonist of the daily comic strip ''Calvin and Hobbes''. Syndicated from 1985 to 1995, this strip is fondly remembered and treasured by the discoverer, and helped him stay awake and sane on long observing nights and during the trials and tribulations of graduate school.<ref name="MPC-Watterson" />
== Notes == {{notelist|refs=
{{efn|name=lcdb-Skiff|1=Skiff (2011) web: rotation period {{val|2.539|0.001}} hours with a brightness amplitude of {{val|0.10}} mag. CALL assigns a Quality Code of 3-, which denotes a slightly less than secure result within the precision given and no ambiguity. Summary figures for (7784) Watterson at [http://www.minorplanet.info/PHP/generateOneAsteroidInfo.php?AstInfo=7784%7CWatterson Collaborative Asteroid Lightcurve Link (CALL)]}}
}} <!-- end of notelist -->
== References == {{reflist|30em|refs=
<ref name="jpldata">{{cite web |type = 2017-05-02 last obs. |title = JPL Small-Body Database Browser: 7784 Watterson (1994 PL) |url = https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2007784 |publisher = Jet Propulsion Laboratory |access-date = 22 June 2017}}</ref>
<ref name="MPC-Watterson">{{cite web |title = 7784 Watterson (1994 PL) |work = Minor Planet Center |url = https://www.minorplanetcenter.net/db_search/show_object?object_id=7784 |access-date = 6 February 2016}}</ref>
<ref name="Ferret">{{cite web |title = Asteroid 7784 Watterson – Nesvorny HCM Asteroid Families V3.0 |work = Small Bodies Data Ferret |url = https://sbntools.psi.edu/ferret/SimpleSearch/results.action?targetName=7784+Watterson#Asteroid%207784%20WattersonEAR-A-VARGBDET-5-NESVORNYFAM-V3.0 |access-date = 27 October 2019}}</ref>
<ref name="lcdb">{{cite LCDB|number = 7784 |access-date = 6 February 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 |access-date= 6 February 2016|arxiv = 1109.6407 }}</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= 11 March 2017}}</ref>
}} <!-- 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/NumberedMPs005001.html Discovery Circumstances: Numbered Minor Planets (5001)-(10000)] – Minor Planet Center * {{AstDys|7784}} * {{JPL small body}}
{{Minor planets navigator | |number=7784 |(7785) 1994 QW}} {{Small Solar System bodies}} {{Authority control}}
{{DEFAULTSORT:Watterson}} 007784 Category:Discoveries by Timothy B. Spahr Category:Named minor planets 19940805