Axis inclination
As axis tilt (also: axis tilt , Achsschiefe ), in a measuring instrument , the deviation of an axis of the horizontal or vertical respectively.
In astronomy , the angle between the axis of rotation of a celestial body and the normal of its orbital plane (orbit) is also referred to as axis inclination .
measuring technology
Axle inclination affects i. a. as a systematic error on the measurement and must therefore be considered and eliminated separately. The most common method for this is to attach an exact level or a digital sensor to the axis and read it during the measurement and then in the opposite position of the device.
For universal instruments and theodolites , the following axis inclinations are distinguished:
- Standing axis error - the deviation of the vertical axis of rotation from the plumb line . The aim is to keep it below about 10 ″ when setting up the instrument and to measure the rest using the alidade or rider level or a sensory compensator . Its effect on a target point increases with the tangent of the elevation angle .
- Tilt axis error - the slope of the horizontal axis on which the rifle scope sits; but also the design-related non- orthogonality between the standing and tilting axis. It can be eliminated by measuring in two circular positions .
- Sighting axis error - the non-orthogonality between the tilt and sighting axes . It can also be eliminated by the measuring arrangement, but must first be brought to a value below about 10 ″ by adjusting the crosshairs (which corresponds to about 0.01 mm).
With the leveling device , only the axis inclination in the direction of the telescope is relevant and with modern instruments it is automatically compensated by a precise pendulum body ( automatic leveling ). In the case of channel lasers and other targeting instruments, it must be brought to zero by precise calibration , whereas in the case of fixed systems in mechanical engineering it is eliminated by adjustment in the bearings .
astronomy
The axis inclination of a planet or moon is the angle between its axis of rotation and the normal on its orbital plane . You determined u. a. the seasons occurring on this celestial body . Axial inclinations between 90 ° and 270 ° characterize a retrograde (retrograde) rotation.
The earth currently has an axis inclination of 23 ° 26 ′ 21,406 ′ ′ (23.44 °), which also defines the polar circles and tropics . (For the cyclical change of this value see here .)
Individual evidence
- ↑ Astronomical Constants ( Memento from June 20, 2019 in the Internet Archive ) on asa.usno.navy.mil
- ↑ NSSDC Earth Fact Sheet (21.406 seconds / 60 = 0.3567 minutes, 26.3567 minutes / 60 = 0.4393 degrees)