altazimuthn.
/alˈtazᵻməθ/, U.S. /ælˈtæzəməθ/, /ɑlˈtæzəməθ/ Chiefly Astronomy.
A telescope mounted so as to move in both a vertical and a horizontal plane, used to determine the altitude and the azimuth of a star or other distant object, or (in surveying) to determine vertical and horizontal angles more precisely than a theodolite. Also: a mounting characteristic of such an instrument, an altazimuth mounting.
ΘΚΠ
the world > the universe > cosmology > science of observation > astronomical instruments > measuring altitude > [noun] > and azimuth
altazimuth1851
1851 Monthly Notices Royal Astron. Soc. 11 98 When the altitude and azimuth instrument (or altazimuth as it is now called) was mounted, it was intended that its zero-point in azimuth should be determined solely by observations of stars in azimuth, the corresponding time being found by comparison of the altazimuth-clock with the transit-clock.
1868 J. N. Lockyer Elem. Lessons Astron. §523 To make an observation with the altazimuth.
1899 Rep. Astronomer Royal Board of Visitors 11 A chronograph for use with the altazimuth is being made by Sir Howard Grubb.
1919 E. de K. Leffingwell Canning River Region Northern Alaska 30/1 During the first two years the altazimuth was used for determining horizontal directions.
1998 Mod. Astronomer Mar. 58/1 Each telescope is mounted in alt-azimuth and will therefore be able to point to all points of the sky.
2011 G. Hayter-Menzies Empress & Mrs. Conger ix. 89 The Empress Dowager Cixi was looking to a murkier future, via human instruments of a vintage pre-dating the bronze altazimuths at the Beijing Observatory.
Compounds
C1. General attributive.
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1851Altazimuth-clock [see main sense].
1860 E. Dunkin Handbk. Astron. §49 The Greenwich altazimuth instrument.
1927 Geogr. Jrnl. 69 140 On the first look one's thoughts immediately go to the altazimuth theodolite, and one is tempted to regard the dioptra as the first of such instruments.
1964 New Scientist 27 Feb. 526/1 The moving part of the telescope will weigh about 300 tons and this mass is to be mounted on ‘altazimuth’ axes rigid enough to permit it to be positioned and controlled to within two minutes of arc.
2001 J. Franzen Corrections 233 The camera was..mounted on an altazimuth bracket above the back door.
C2.
altazimuth mount n. = altazimuth mounting n.
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1882 Eng. Mech. 27 Oct. 193/3 I have a Lancaster Altazimuth mount, and want to know how I can make it steadier.
1958 Proc. Royal Soc. 248 223 The mirrors were supported in their standard searchlight barrels on alt-azimuth mounts.
1998 Sci. News 19 Mar. 188/2 The trend among modern telescopes..is to use an altazimuth mount.
altazimuth mounting n. a mounting for telescopes, guns, etc., with two mutually perpendicular axes, enabling rotation about both a horizontal and a vertical axis.
ΚΠ
1877 G. F. Chambers Handbk. Descr. Astron. (ed. 3) vii. ii. 640 A form of altazimuth mounting for Newtonian Reflectors.
1975 B. V. Barlow Astron. Telescope vii. 122 The only way to drive an altazimuth mounting with optical precision is under computer control.
2009 A. Cooke Make Time for Stars ii. 14 It is about the simplest and cheapest concept to buy or build. Just a standard Newtonian set on a massively large altazimuth mounting.
This entry has been updated (OED Third Edition, September 2012; most recently modified version published online December 2021).
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n.1851