Editing Alvan Graham Clark

{{short description|19th-century American astronomer}}
{{Use mdy dates|date=April 2021}}
{{Infobox scientist
| name                    = Alvan Graham Clark
| image                   = Yerkes Observatory Astro4p6.jpg
| image_size              = 260px
| caption                 = Alvan Clark and his assistant Carl Lundin (right) alongside the 40-inch lens, 1896
| birth_date              = {{birth date|1832|7|10|mf=y}}
| birth_place             = [[Fall River, Massachusetts|Fall River]], Massachusetts
| death_date              = {{death date and age|1897|6|9|1832|3|8|mf=y}}
| death_place             = [[Cambridge, Massachusetts|Cambridge]], Massachusetts
| residence               = 
| citizenship             =
| nationality             = American
| ethnicity               =
| field                   = [[Astronomy]]
| work_institution        = 
| alma_mater              = 
| doctoral_advisor        = 
| doctoral_students       = 
| known_for               = [[Sirius B]]
| author_abbreviation_bot = 
| author_abbreviation_zoo = 
| prizes                  = 
| signature               = Signature of Alvan Graham Clark (1832–1897).png
| footnotes               = 
}}
'''Alvan Graham Clark''' (July 10, 1832 – June 9, 1897) was an American [[astronomer]] and [[telescope]]-maker.

==Biography==
Alvan Graham Clark was born in [[Fall River, Massachusetts|Fall River]], [[Massachusetts]], the son of [[Alvan Clark]], founder of [[Alvan Clark & Sons]].<ref name=Cyclopaedia>{{Cite book |url=https://books.google.com/books?id=4FxDAQAAMAAJ&pg=PA386 |title=The National Cyclopaedia of American Biography |volume=V |publisher=James T. White & Company |page=386 |year=1907 |access-date=2021-04-02 |via=Google Books}}</ref>

On January 31, 1862, while testing a new {{convert|18.5|in|mm|adj=on}} aperture [[great refractor]] telescope in [[Cambridgeport]], [[Massachusetts]], Clark made the first ever observation of a [[white dwarf]] star.  This discovery of [[Sirius#Sirius B|Sirius B]], or affectionately "the Pup", proved an earlier hypotheses ([[Friedrich Wilhelm Bessel]] in 1844) that [[Sirius]], the brightest star in the night sky with an [[apparent magnitude]] of −1.46, had an unseen companion disturbing its motion.  Clark used the largest refracting telescope lens in existence at the time, and the largest telescope in the United States, to observe the magnitude 8 companion.

Clark's 18.5 inch refracting telescope was then delivered to his customer, the landmark [[Dearborn Observatory]] of [[Northwestern University]] in [[Evanston, Illinois]], where it is still being used today.<ref>[http://www.physics.northwestern.edu/about/dearborn-observatory/history.html Dearborn Observatory: History]</ref>

Alvan Graham Clark died in [[Cambridge, Massachusetts]] on June 9, 1897.<ref>{{Cite news |url=https://www.newspapers.com/clip/74960085/deaths/ |title=Deaths |newspaper=[[The Boston Globe]] |page=10 |date=1897-06-10 |access-date=2021-04-02 |via=Newspapers.com}}</ref>

==See also==
*[[List of astronomical instrument makers]]

==References==
{{Reflist}}
* {{cite encyclopedia | url = http://reference.allrefer.com/encyclopedia/C/Clark-Al.html | title = Alvan Clark, Astronomy, Biographies | encyclopedia = AllRefer.com | url-status = dead | archive-url = https://web.archive.org/web/20040623152608/http://reference.allrefer.com/encyclopedia/C/Clark-Al.html | archive-date = 2004-06-23 }}
* [http://www.deller.com/newpage6.htm The Dearborn Telescope]
* [http://chandra.harvard.edu/photo/2000/0065/index.html Sirius A & B: A Double Star System In The Constellation Canis Major]
* [http://www.astro.northwestern.edu/Observatory/chronology2.html Northwestern University Astronomy and Astrophysics – History of Dearborn Observatory] {{Webarchive|url=https://web.archive.org/web/20190713091718/http://www.astro.northwestern.edu/Observatory/chronology2.html |date=July 13, 2019 }}
* [http://www.boston.com/news/local/articles/2008/02/02/look_south_to_see_winters_brightest_constellations Look south to see winter's brightest constellations]

==External links==
* [http://digitalcollections.ucsc.edu/cdm/search/collection/p265101coll10/searchterm/Alvan%20Graham%20Clark/order/title Portraits of Alvan Graham Clark from the Lick Observatory Records Digital Archive, UC Santa Cruz Library's Digital Collections] {{Webarchive|url=https://web.archive.org/web/20170407004324/http://digitalcollections.ucsc.edu/cdm/search/collection/p265101coll10/searchterm/Alvan%20Graham%20Clark/order/title |date=April 7, 2017 }}

{{Authority control}}

{{DEFAULTSORT:Clark, Alvan Graham}}
[[Category:1832 births]]
[[Category:1897 deaths]]
[[Category:American astronomers]]
[[Category:People from Fall River, Massachusetts]]