Equatorial sextant explained

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,^[1] 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.^[2] Flamsteed used this instrument to measure angles of right ascension from 1676 through 1689^[3] or 1690.^[4]

Another device known by that name was patented by the American inventor William Austin Burt in 1856.^[5] 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.^[6]

Notes and References

1. Laurie . P. S. . 1960 . The buildings and old instruments of the Royal Observatory, Greenwich . The Observatory . 80 . 12–22. 1960Obs....80...13L .
2. Chapman . Allan . September 1984 . Tycho Brahe in China: the Jesuit mission to Peking and the iconography of European instrument-making processes . Annals of Science . en . 41 . 5 . 417–443 . 10.1080/00033798400200341 . 0003-3790.
3. Web site: Telescope: Flamsteed's 7-foot Equatorial Sextant (1676) . 2023-03-01 . www.royalobservatorygreenwich.org.
4. Chapman . Allan . September 1995 . Out of the meridian: John Bird's equatorial sector and the new technology of astronomical measurement . Annals of Science . en . 52 . 5 . 431–463 . 10.1080/00033799500200341 . 0003-3790.
5. Web site: Equatorial Sextant . 2023-02-28 . National Museum of American History . en.
6. Book: Briley-Webb, Linda . Technical Innovation in American History: An Encyclopedia of Science and Technology [3 volumes] ]. 2019-02-22 . ABC-CLIO . 978-1-61069-094-2 . Welch . Rosanne . 225–226 . en . Equatorial sextant . Lamphier . Peg A..