declination axis

declination axis

The axis at right angles to the polar axis about which a telescope on an equatorial mounting is turned in order to make adjustments in declination. The optical axis then follows a particular hour circle across the sky.
Collins Dictionary of Astronomy © Market House Books Ltd, 2006
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Declination Axis

 

one of the axes of an equatorial mount of a telescope. The declination axis is perpendicular to the polar axis. The telescope is rotated about the declination axis as it is directed to a given point on the celestial sphere.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

declination axis

[‚dek·lə′nā·shən ‚ak·səs]
(engineering)
For an equatorial mounting of a telescope, an axis of rotation that is perpendicular to the polar axis and allows the telescope to be pointed at objects of different declinations.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
The unusual positioning of the declination axis near the middle of the polar axis helps keep the mass of a setup (mount, telescope, and counterweights) roughly centered over the base of the mount, unlike a conventional German equatorial that is typically very off balance toward its celestial-pole end.
First-time mechanical setup took me less than an hour, since it involves only connecting the mount to the pier with four hand knobs, threading on the stainless-steel counterweight shaft, and attaching the telescope-mounting plate to the top of the declination axis. Only this last operation required that I consult the manual, since the plate can be positioned several ways but needs to be oriented properly depending on whether its long dimension is to be in line with the telescope's optical axis or perpendicular to it.
Because the mount's declination axel rotates as a solid unit from the telescope saddle to the end of the counterweight shaft (something that I especially like, since it lets you attach guided cameras to the counterweight shaft), it's impossible to route cables through the declination axis. Cable management was an issue for me because I made so many setup changes during the course of testing the mount, and at times I was a bit careless about letting wires hang freely from the scopes, with predictably unfortunate results.
The drive mechanism for the declination axis has a slip clutch that retains the manual slow-motion feature, but there isn't a similar clutch for the polar-axis drive.
A diagram of an altazimuth mount on page 28 includes the labels "polar axis" and "declination axis." The author explains the 11-year sunspot cycle in Chapter 1, but she gives no indication when sunspot activity peaked in the past or when it will peak in the future.
This reconciles any inherent "cone error" in the CGE mount, caused by the scope's optical axis not being exactly perpendicular to the declination axis. Mount calibration involves slewing to and centering a star on the opposite side of the meridian from the initial alignment stars.
Caption: The equatorial head can be separated into two pieces with the RA axis and polar base (left) weighing 26 pounds, and the declination axis (right) weighing 18 pounds.
Remove the end caps from the VX's right ascension housing, turn the scope perpendicular to the mount's head to open up a hole in the declination axis, and then sight Polaris through the hollow polar bore.
Both RA and dec motors are housed within the declination axis, functioning as a built-in counterweight.
The justification was that the declination axis could be much shorter than a large wormwheel would allow.
You'll also want a motor drive on the declination axis, and electronics that are suited to making very precise tracking corrections (called guiding) either manually or with an electronic autoguider.
The fight ascension axis rotates an equational fork that is mounted in the optical tube assembly, which contains the telescope mirrors and is positioned by the declination axis drive.