- Industry: Earth science
- Number of terms: 93452
- Number of blossaries: 0
- Company Profile:
Founded in 1941, the American Congress on Surveying and Mapping (ACSM) is an international association representing the interests of professionals in surveying, mapping and communicating spatial data relating to the Earth's surface. Today, ACSM's members include more than 7,000 surveyors, ...
The angle, at a point A on a surface, between the tangent to the meridian at A and the tangent to the geodesic from A to the point B whose geodetic azimuth is wanted. The angle is measured from the direction of north clockwise. (Until 1985, the U. S. National Geodetic Survey (NGS) and some other organizations measured the angle from the direction of south clockwise. ) The angle is called the forward azimuth for the line AB. The azimuth at B between the tangent to the meridian and the tangent to the geodesic is called the back azimuth or reverse azimuth of the line AB. The geodesic is not, except in special cases, a plane curve. However, for short lines of the length commonly used in triangulation, the small difference between the tangent to the geodesic and the tangent to the actual line of sight between A and B can be neglected.
Industry:Earth science
The angle between the actual line of sight of a telescope and the direction in which the horizontal or vertical circles or on an auxiliary telescope indicate that the line of sight should lie.
Industry:Earth science
One or more point like masses taken to be of such a size and distribution as to account for deviations of the Earth's gravity field from that of an ellipsoid having the same mass, center of mass, rate of rotation as the Earth, and the same gravity potential on its surface as on the geoid.
Industry:Earth science
(1) An estimate and opinion of value.
(2) Usually, a written statement of the market value or the value as defined by the appraisal, of an adequately described parcel of property as of a specific date.
(3) A conclusion that results from an analysis of facts.
Industry:Earth science
Any process in which the flux density, power, amplitude, intensity, or illuminance, etc. , of radiation decreases with increasing distance from the source.
Industry:Earth science
A set of values describing atmospheric conditions on which ballistic computations are based, namely: a surface temperature of 15°C; a surface pressure of 1000 millibars; a relative humidity at the surface of 78%; a lapse rate which yields a prescribed relation of density to altitude; and no wind.
Industry:Earth science
A contact base-line apparatus consisting of two disconnected bars, one of brass and the other of steel, each 5 meters in length and so arranged as to indicate the accumulated differences of length of the measures from the brass and steel components. Similar in concept to Bessel's base-line apparatus.
Industry:Earth science
The near approach of one celestial body to another on the celestial sphere, as in conjunction or occultation.
Industry:Earth science
An axis generally along the main body of a craft, in the direction of motion. Its precise definition is usually set by the constructor of the craft. It frequently serves as a reference for directions in navigation and in surveying.
Industry:Earth science
That aperture (2) for which the unsharpness caused by diffraction most nearly balances the unsharpness caused by aberration.
Industry:Earth science
