View source for Charles T. Kowal

{{Short description|American astronomer (1940–2011)}}
{{Infobox scientist
| name              = Charles Thomas Kowal
| image             = Charles_T._Kowal.jpg
| caption           = 
| birth_date        = {{birth date|1940|11|8}}
| birth_place       = [[Buffalo, New York]], [[United States|USA]]
| death_date        = {{death date and age|2011|11|28|1940|11|8}}
| death_place       = [[Cinebar, Washington]], US
| fields            = [[Astronomy]]
| workplaces        = [[California Institute of Technology|Caltech]]'s [[Palomar Observatory|Hale Observatory]], [[Space Telescope Science Institute|STScI]], [[Johns Hopkins University Applied Physics Laboratory|APL]]
| alma_mater        = [[University of Southern California]]
| known_for         = Discovery of outer Solar System objects
| footnotes         = <!--For any footnotes needed to clarify entries above-->
}}

{| class="wikitable floatright" style="font-size: 0.9em; width: 270px;"
|+ [[Minor planet]]s discovered: 22<ref name="MPC-Discoverers" />
|-
| ''see {{section link||List of discovered minor planets}}''
|}

'''Charles Thomas Kowal''' (November 8, 1940 – November 28, 2011) was an American [[astronomer]] known for his observations and discoveries in the [[Solar System]]. As a staff astronomer at [[Caltech]]'s [[Mount Wilson Observatory|Mount Wilson]] and [[Palomar Observatory|Palomar Mountain]] observatories between 1961 and 1984, he found [[2060 Chiron]], the second-largest [[centaur (minor planet)|centaur]], discovered two moons of the planet [[Jupiter]], and discovered or co-discovered a number of [[asteroid]]s, [[comet]]s and [[supernova]]e. He was awarded the [[James Craig Watson Medal]] for his contributions to astronomy in 1979.

== Research ==

In the 1960s, Kowal observed with the Palomar [[Samuel Oschin telescope|48" Schmidt telescope]], contributing observations to noted [[cosmologist]] [[Fritz Zwicky]]'s six-volume ''Catalogue of Galaxies and of Clusters of Galaxies''.{{#tag:ref|Kowal was a coauthor on volumes 1, 5 and 6.<ref name="ADScat">{{cite web | url=http://adsabs.harvard.edu/cgi-bin/nph-abs_connect?db_key=AST&db_key=PRE&qform=AST&arxiv_sel=astro-ph&arxiv_sel=cond-mat&arxiv_sel=cs&arxiv_sel=gr-qc&arxiv_sel=hep-ex&arxiv_sel=hep-lat&arxiv_sel=hep-ph&arxiv_sel=hep-th&arxiv_sel=math&arxiv_sel=math-ph&arxiv_sel=nlin&arxiv_sel=nucl-ex&arxiv_sel=nucl-th&arxiv_sel=physics&arxiv_sel=quant-ph&arxiv_sel=q-bio&sim_query=YES&ned_query=YES&adsobj_query=YES&aut_req=YES&aut_logic=OR&obj_logic=OR&author=zwicky&object=&start_mon=&start_year=&end_mon=&end_year=&ttl_req=YES&ttl_logic=OR&title=%22Catalogue+of+Galaxies+and+of+Clusters+of+Galaxies%22&txt_logic=OR&text=&nr_to_return=200&start_nr=1&jou_pick=ALL&ref_stems=&data_and=ALL&group_and=ALL&start_entry_day=&start_entry_mon=&start_entry_year=&end_entry_day=&end_entry_mon=&end_entry_year=&min_score=&sort=SCORE&data_type=SHORT&aut_syn=YES&ttl_syn=YES&txt_syn=YES&aut_wt=1.0&obj_wt=1.0&ttl_wt=0.3&txt_wt=3.0&aut_wgt=YES&obj_wgt=YES&ttl_wgt=YES&txt_wgt=YES&ttl_sco=YES&txt_sco=YES&version=1 | title=Query Results from the ADS Database | accessdate=December 6, 2011}}</ref>|group="nb"}} Kowal also began to search for [[Type Ia supernova]]e in other galaxies, in an effort led by Zwicky to calibrate the magnitudes of these exploding stars so that they could be used as [[standard candle]]s, reliable measures of the distance of their host galaxies (work which in the present has led to accurate measurements of the [[expansion of the universe]]).<ref name="Kowal1968">{{cite journal | title=Absolute magnitudes of supernovae. | author=Kowal, C. T. | journal=Astronomical Journal |date=December 1968 | volume=73 | pages=1021–1024|bibcode = 1968AJ.....73.1021K |doi = 10.1086/110763 | doi-access=free }}</ref> In the course of these Palomar supernovae surveys with the 48" Schmidt,<ref name="69survey">{{cite journal | title=The 1969 Palomar Supernova Search |author1=Kowal, C. T. |author2=Sargent, W. L. W. |author3=Zwicky, F. | journal=Publications of the Astronomical Society of the Pacific |date=June 1970 | volume=82 | issue=487 | pages=736 | doi=10.1086/128951 | bibcode=1970PASP...82..736K| doi-access=free }}</ref> Kowal personally discovered 81 supernovae, including [[SN 1972E]].

In 1973, Caltech astronomers [[Eleanor Helin]] and [[Gene Shoemaker]] began an observing program to search out and track previously unknown [[near-Earth asteroid]]s, the [[Planet-Crossing Asteroid Survey]] (PCAS), a photographic plate survey that began on the Palomar 18" Schmidt telescope. Although primarily employed by the supernova survey to observe on the 48" Schmidt, Kowal provided "crucial observations"<ref name="IcarusPCAS">{{cite journal | title=The Palomar planet-crossing asteroid survey, 1973–1978 |author1=Helin, E. F. |author2=Shoemaker, E. M. | journal=Icarus | year=1979 | volume=40 | issue=3 | pages=321–328 | doi=10.1016/0019-1035(79)90021-6 | bibcode=1979Icar...40..321H}}</ref> of particularly faint asteroids for the PCAS program with the larger telescope. His asteroid discoveries and co-discoveries include the notable asteroids [[Aten asteroid]] [[2340 Hathor]]; the [[Apollo asteroid]]s [[1981 Midas]], [[2063 Bacchus]], [[2102 Tantalus]] and [[(5660) 1974 MA]]; the [[Amor asteroid]]s [[(4596) 1981 QB]] and [[(4688) 1980 WF]]; and the [[Trojan asteroid]]s [[2241 Alcathous]] and [[2594 Acamas]]. PCAS later moved to the 48" Schmidt, and ran in total for nearly 25 years, until June 1995.{{#tag:ref|The 48" Schmidt was then fully automated, and used for a successor survey, the [[Near Earth Asteroid Tracking]] (NEAT) survey,<!---began in Hawaii in Dec 1995---> which ran on the Schmidt from April 2001 to April 2007.|group="nb"}}

Kowal provided observations of new Solar System discoveries and reports of new supernovae via the [[IAU circular]] system throughout the 1970s,<ref name="ADSKowal">{{cite web | url=http://adsabs.harvard.edu/cgi-bin/nph-abs_connect?return_req=no_params&author=Kowal,%20C.%20T.&db_key=AST | title=Author Query: Kowal, C. T. Query Results from the Astronomy Database | publisher=ADS | accessdate=December 6, 2011}}</ref> and searched for new objects. He discovered two [[natural satellite|moons]] of [[Jupiter]]: [[Leda (moon)|Leda]] in 1974 and [[Themisto (moon)|Themisto]] in 1975, the 13th and 14th moons of Jupiter to be found.<ref name="Leda">{{cite web | url=http://www.cbat.eps.harvard.edu/iauc/02800/02846.html#Item6 | title=IAUC 2846: N Mon 1975 (= A0620-00); N Cyg 1975; 1975h; 1975g; 1975i; Sats OF JUPITER | publisher=Central Bureau for Astronomical Telegrams, International Astronomical Union | date=1975-10-07 | accessdate=December 6, 2011 | author=Marsden, Brian G.}}</ref> Themisto was later lost (i.e. its orbit was not known well enough to reobserve it) and was not rediscovered until 2000.

Between December 1976 and February 1985, Kowal searched 6400 square degrees of sky in the [[ecliptic plane]] for distant, slow-moving Solar System objects.<ref name="Kowalsurvey">{{cite journal | title=A solar system survey | author=Kowal, C. T. | journal=Icarus |date=January 1989 | volume=77 | issue=1 | pages=118–123 | doi=10.1016/0019-1035(89)90011-0 | bibcode=1989Icar...77..118K}}</ref> Only one object was found beyond Jupiter: [[2060 Chiron]], discovered in 1977, which had the unusual characteristic of features both like an asteroid and a comet. It became recognised as the first object in the [[Centaur (minor planet)|centaur class]] after a second one was discovered 15 years later. Centaurs are objects with unstable orbits which orbit between Jupiter and [[Neptune]]. They are probably drawn in from the [[Kuiper belt]] by alignments with larger planets. Chiron remains one of the largest such worlds known, and one of a handful that have a comet-like [[coma (cometary)|coma]].
Kowal also discovered or co-discovered the periodic comets [[99P/Kowal]], [[104P/Kowal]], [[134P/Kowal-Vavrova]], [[143P/Kowal-Mrkos]], and [[158P/Kowal-LINEAR]].

In 1980, Kowal's research in astronomical history found a 1613 drawing by [[Galileo Galilei]] showing Neptune near Jupiter, predating the [[discovery of Neptune]] in 1846;<ref name="DIO-Kowal">{{cite journal | url=http://www.dioi.org/vols/wf0.pdf | title=Galileo's Observations of Neptune | journal=The International Journal of Scientific History | date=December 2008 | accessdate=29 March 2016 | last=Kowal | first=Charles T. | authorlink=Charles Thomas Kowal | volume=15 | issue=2008 December | page=3| bibcode=2008DIO....15....3K }}</ref> Kowal was awarded the inaugural [[R. R. Newton Award for Scientific History]] for this "shockingly outré" finding.<ref name="RRaward">{{cite web | url=http://www.dioi.org/pri.htm | title=DIO $1000 Prizes. | publisher=DIO Publishing | accessdate=December 5, 2011}}</ref>

Kowal moved to the new [[Space Telescope Science Institute]] in 1985, where he monitored the instruments of the [[Hubble Space Telescope]] as one of the operations astronomers. His book ''Asteroids: Their Nature and Utilization'' was published in 1988, and a second edition in 1996.

From 1996 until his retirement in 2006, he worked at the [[Johns Hopkins University Applied Physics Laboratory]], providing software for the [[NEAR Shoemaker]] spacecraft's mission to land on the asteroid [[Eros]] and mission operations support for the NASA TIMED mission.

Kowal died on November 28, 2011, at the age of 71.<ref name="Buffalo obit">{{cite web | url=http://www.buffalonews.com/deaths/local-obituaries/article658057.ece | title=Charles T. Kowal, discovered 2 of Jupiter's moons | publisher=[[The Buffalo News]] | date=December 3, 2011<!--, 7:35 AM --> | accessdate=December 5, 2011 | author=News staff reports | archive-date=July 23, 2012 | archive-url=https://archive.today/20120723223215/http://www.buffalonews.com/deaths/local-obituaries/article658057.ece | url-status=dead }}</ref>

== Honours and awards ==
* Kowal was awarded the [[National Academy of Sciences]]' [[James Craig Watson Medal]] for his "noteworthy astronomical discoveries, particularly of Chiron, Leda, and numerous supernovae" in 1979.<ref name="NASmedal">{{cite web | url=http://nas.nasonline.org/site/PageServer?pagename=AWARDS_watson | title=Awards: James Craig Watson Medal | publisher=[[National Academy of Sciences]] | year=2011 | accessdate=December 6, 2011 | url-status=dead | archiveurl=https://web.archive.org/web/20111116073931/http://nas.nasonline.org/site/PageServer?pagename=AWARDS_watson | archivedate=November 16, 2011 }}</ref>
* The crater ''[[Kowal (crater)|Kowal]]'' on [[Pluto]] was named in his honor.<ref>{{Cite web |title=Kowal |url=https://planetarynames.wr.usgs.gov/Feature/16085 |access-date=2023-12-07 |website=Gazetteer of Planetary Nomenclature}}</ref>

== List of discovered minor planets ==
{{See also|Category:Discoveries by Charles T. Kowal}}

{| class="wikitable collapsible collapsed" role="presentation" style="width:100%; background:#ffffff;"
|-
!List of minor planets discovered by Charles Kowal
|-
| align="center" | 
{| class="wikitable" style="width: 30em; display:inline-table; margin:8px; text-align:left; font-size:90%"
|-
! scope="col" style="width: 13.5em;" | Name
! scope="col" style="width: 12em;" | Discovery Date
! scope="col" style="width: 4.5em;"  | Listing
|-
| 1876 Napolitania || 31 January 1970 || {{LoMP|1876|list}}
|-
| '''[[1939 Loretta]]''' || 17 October 1974 || {{LoMP|1939|list}}
|-
| '''[[1981 Midas]]''' || 6 March 1973 || {{LoMP|1981|list}}
|-
| '''[[2060 Chiron]]''' || 18 October 1977 || {{LoMP|2060|list}}
|-
| '''[[2063 Bacchus]]''' || 24 April 1977 || {{LoMP|2063|list}}
|-
| '''[[2102 Tantalus]]''' || 27 December 1975 || {{LoMP|2102|list}}
|-
| '''[[2134 Dennispalm]]''' || 24 December 1976 || {{LoMP|2134|list}}
|-
| '''[[2241 Alcathous]]''' || 22 November 1979 || {{LoMP|2241|list}}
|-
| '''[[2340 Hathor]]''' || 22 October 1976 || {{LoMP|2340|list}}
|-
| '''[[2594 Acamas]]''' || 4 October 1978 || {{LoMP|2594|list}}
|-
| '''[[2629 Rudra]]''' || 13 September 1980 || {{LoMP|2629|list}}
|-
| 3163 Randi || 28 August 1981 || {{LoMP|3163|list}}
|}
{| class="wikitable" style="width: 30em; display:inline-table; margin:8px; text-align:left; font-size:90%"
|-
! scope="col" style="width: 13.5em;" | Name
! scope="col" style="width: 12em;" | Discovery Date
! scope="col" style="width: 4.5em;"  | Listing
|-
| 3924 Birch || 11 February 1977 || {{LoMP|3924|list}}{{ref label|codisc|A|}}
|-
| 4312 Knacke || 29 November 1978 || {{LoMP|4312|list}}{{ref label|codisc|B|}}
|-
| {{mp|(4596) 1981 QB}} || 28 August 1981 || {{LoMP|4596|list}}
|-
| {{mp|(4688) 1980 WF}} || 29 November 1980 || {{LoMP|4688|list}}
|-
| {{mp|(5660) 1974 MA}} || 26 June 1974 || {{LoMP|5660|list}}
|-
| {{mp|(24617) 1978 WU}} || 29 November 1978 || {{LoMP|24617|list}}{{ref label|codisc|B|}}
|-
| {{mp|(73669) 1981 WL|2}} || 25 November 1981 || {{LoMP|73669|list}}
|-
| {{mp|(99953) 1978 ND}} || 7 July 1978 || {{LoMP|99953|list}}
|-
| {{mp|(178284) 1978 WB|1}} || 29 November 1978 || {{LoMP|178284|list}}{{ref label|codisc|B|}}
|-
| {{mp|(306375) 1980 RG|1}} || 13 September 1980 || {{LoMP|306375|list}}
|-
! colspan=3 style="font-weight: normal; text-align: left; padding: 4px 12px;" |'''Co-discovery''' made with:<br />{{note label|codisc|A|}} [[Edward L. G. Bowell|E. Bowell]]<br />{{note label|codisc|B|}} [[Schelte J. Bus|S. J. Bus]]
|}
|}

== See also ==
* {{section link|List of minor planet discoverers|C. T. Kowal}}

== Notes ==
{{reflist|group="nb"}}

== References ==
{{reflist|35em|refs=

<ref name="MPC-Discoverers">{{cite web
  |title      = Minor Planet Discoverers (by number)
  |work       = Minor Planet Center
  |url        = https://www.minorplanetcenter.net/iau/lists/MPDiscsNum.html
  |date       = 29 October 2018
  |accessdate = 19 February 2019}}</ref>

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

{{Use mdy dates|date=February 2019}}
{{Authority control}}

{{DEFAULTSORT:Kowal, Charles T.}}
[[Category:1940 births]]
[[Category:2011 deaths]]
[[Category:20th-century American astronomers]]
[[Category:Discoveries by Charles T. Kowal|*]]
[[Category:Discoverers of asteroids]]
[[Category:Discoverers of comets]]
[[Category:Discoverers of supernovae]]
[[Category:Discoverers of moons]]
[[Category:University of Southern California alumni]]