- 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, ...
A navigation system determining the distance of a mobile unit from a single, fixed station and the direction of that unit from a pair of fixed stations (one of which may be at the same point as the station used in determining distance). The mobile unit determines its distance from the single station by measuring the time it takes a signal to travel between it and that station. This locates the unit somewhere on a circle of known center and radius. At the same time, it determines the difference in its distances from the two fixed stations, locating the station somewhere on a hyperbola of known position. However, because the two stations of the pair are very close together, this difference can be converted into an approximate direction to the mid-point of the line joining the pair. The combination of distance and direction gives the location of the mobile unit.
Industry:Earth science
A coordinate system based on a terrestrial ellipsoid and using geodetic longitude and latitude for two of the coordinates of a point, but using as the third coordinate the potential of the level surface through that point.
Industry:Earth science
The sum of the component masses of a rotating body times the square of the distance of each component mass from the axis of rotation.
Industry:Earth science
A complete piece of copy for reproduction, consisting of an accurate assemblage of paste-ups of text, display matter, line drawings, and illustrations. (jargon)
Industry:Earth science
A graduated ring fitted to a globe in such a manner that its plane contains the poles of the globe and so that it can be adjusted into the plane of any given great circle representing a meridian. A meridian ring is used for measuring angles along a line representing a meridian.
Industry:Earth science
Any method in which the Moon's right ascension is determined at two points, one of which is at a known astronomic longitude and the other is at the longitude to be determined. The difference in longitude is determined from the difference in right ascension and the Moon's hourly rate of motion in right ascension. The Moon may also be observed at equal angular elevations, or at any angular elevation. Longitude may be determined by measuring the angle between the Moon and the Sun, or between the Moon and the zodiacal stars. Occultations may be used for determining longitudes; these usually give information about latitude also.
Industry:Earth science
(1) An isolated, nearly level region standing distinctly above the surrounding country, bounded by steeply sloping sides, and capped by layers of erosion-resistant rock. (2) A very broad, flat-topped, usually isolated hill or mountain of moderate height bounded on at least one side by a steep cliff or slope and created by erosion of the surrounding land. A mesa is similar to a butte but has a more extensive summit.
Industry:Earth science
A map at a scale smaller than that commonly used for maps of counties or metropolitan regions but larger than that used for maps of continents or the world. The term may be considered roughly equivalent to medium-scale map. A map at a scale between 1:50 000 and 1:500 000 would usually be considered an intermediate scale map.
Industry:Earth science
A method of determining simultaneously the locations of two unknown points by resection from four known points.
Industry:Earth science
The angle from the reference plane through the Moon's average axis of rotation to the plane through the same axis and the point of interest, taken as positive when measured from east to west (i.e, toward Mare Crisium).
Industry:Earth science
