equatorial sextant

{{short description|Navigational instrument}}

File:Burt equatorial sexton 1915.jpg

An equatorial sextant is a modified version of a sextant. One historically significant instrument called by that name was John Flamsteed's equatorial sextant, installed in the Greenwich Observatory in 1676. Seven feet across and possessing an iron frame,{{Cite journal |last=Laurie |first=P. S. |date=1960 |title=The buildings and old instruments of the Royal Observatory, Greenwich |url=https://adsabs.harvard.edu/full/1960Obs....80...13L |journal=The Observatory |volume=80 |pages=12–22|bibcode=1960Obs....80...13L }} it was mounted at an angle that aligned with the celestial equator, so that as it rotated, it tracked the motion of objects across the night sky.{{Cite journal |last=Chapman |first=Allan |date=September 1984 |title=Tycho Brahe in China: the Jesuit mission to Peking and the iconography of European instrument-making processes |url=https://www.tandfonline.com/doi/full/10.1080/00033798400200341 |journal=Annals of Science |language=en |volume=41 |issue=5 |pages=417–443 |doi=10.1080/00033798400200341 |issn=0003-3790}} Flamsteed used this instrument to measure angles of right ascension from 1676 through 1689{{Cite web |title=Telescope: Flamsteed's 7-foot Equatorial Sextant (1676) |url=http://www.royalobservatorygreenwich.org/articles.php?article=937 |access-date=2023-03-01 |website=www.royalobservatorygreenwich.org}} or 1690.{{Cite journal |last=Chapman |first=Allan |date=September 1995 |title=Out of the meridian: John Bird's equatorial sector and the new technology of astronomical measurement |url=https://www.tandfonline.com/doi/full/10.1080/00033799500200341 |journal=Annals of Science |language=en |volume=52 |issue=5 |pages=431–463 |doi=10.1080/00033799500200341 |issn=0003-3790}}

Another device known by that name was patented by the American inventor William Austin Burt in 1856.{{Cite web |title=Equatorial Sextant |url=https://americanhistory.si.edu/collections/search/object/nmah_1167859 |access-date=2023-02-28 |website=National Museum of American History |language=en}} Burt's equatorial sextant included several elaborations on the basic sextant design, which enabled its user to determine navigational information without a supplemental chart or the need for calculation.{{Cite book |last=Briley-Webb |first=Linda |url=https://books.google.com/books?id=aWGHDwAAQBAJ |title=Technical Innovation in American History: An Encyclopedia of Science and Technology [3 volumes] |date=2019-02-22 |publisher=ABC-CLIO |isbn=978-1-61069-094-2 |editor-last1=Welch |editor-first1=Rosanne |pages=225–226 |language=en |chapter=Equatorial sextant |editor-last2=Lamphier |editor-first2=Peg A.}}