- 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, ...
(1) The evidences or writing whereby one is enabled to defend the title to an estate or maintain a claim to rights or privileges. (2) Specifically, title, deeds and papers.
Industry:Earth science
(1) A particular stage in the history of a phenomenon going through a cyclic sequence of stages. Examples are the phases of the Moon, the phase of an alternating current and the phase of a variable star. (2) The visible aspect of an object. The exact meaning varies somewhat, according to the application. In particular, the following special meanings are common. (3) In surveying, the appearance of a signal which presents regions of varying brightness to the observer, e.g. a round pole, illuminated from the side; a square pole, of which the observer sees two sides, one more strongly illuminated than the other. Phase causes the telescope to be pointed in a direction slightly different from that of the vertical axis of the pole or rod. The error is of the same character and requires the same treatment as an error caused by observing an eccentric object. Phase may be closely associated with asymmetry of object (target), but the two terms are not synonymous. (4) The ratio of the illumi-nated area of the apparent disk of a celestial body to the area of the entire apparent disk taken as a circle. For the Moon, phases (total, partial, penumbral, etc.) are designated according to specific configurations of the Sun, Earth and Moon. For eclipses, designations provide general descrip-tions of the phenomena (solar eclipse, lunar eclipse, annular eclipse, etc.)
Industry:Earth science
Navigation depending on equipment having a range longer than that used for approaches but shorter than that used for long range navigation. There are no generally accepted demarcations between the three types.
Industry:Earth science
A class of map projections mapping one standard parallel and the central meridian into lines along which principal scale is preserved. In the normal aspect of the graticule, parallels of latitude are represented by concentric circular arcs and meridians by convergent curves. The Bonne map-projection is the most common.
Industry:Earth science
The mechanical determination of coordinates of points on an object, using stereoscopic pairs of photographs of the object. The term should be usable whether the photographs are stereoscopic pairs or not, but common usage is as given.
Industry:Earth science
(1) Motion relative to a point fixed on the Earth or to an apparently fixed celestial point. (2) The motion, of an object, described by its measurement in a coordinate system preferred over all other coordinate systems.
Industry:Earth science
The determination of the locations of both ends of an air base with respect to a system of coordinates on the ground. Six quantities - the three coordinates of each end of the air base or their equivalents - are required. In practice, these quantities may also be expressed as (a) the coordinates of one end of the air base and the three differences between these and the coordinates of the other end, or (b) the coordinates of one end of the air base, the length of the air base, and the direction (two angles) of the air base.
Industry:Earth science
The formula α = T <sub>obs</sub> ΔT + a sin( φ'- δ) sec δ + b cos( φ' - δ) + c* sec δ, in which α is the right ascension of the star observed, T <sub>obs</sub> is the time at which the star was observed to pass through the meridian, ΔT is the clock correction, φ' is the latitude of the observer and δ is the declination of the star. a, b, and c* are constants characteristic of the instrument used: a is the azimuth error, b the level error and c* the collimation error. This formula applies to observations made at the upper culmination of the star. For use on observations made at lower culmination, the sign of δ is changed. Bessel's formula and Mayer's formula are equally suitable for computing when, as is almost always the case, the errors in azimuth, leveling and collimation are small. When these errors are large, Bessel's formula should be used.
Industry:Earth science
The direction indicated by the north-seeking end of an unconstrained, magnetized needle. Compass north and magnetic north differ in that the former is influence by reactions between the needle and its support and bearing.
Industry:Earth science
A spindle or pin supporting a movable part of an instrument in such a way that the part is free to turn. The pivot of a compass is usually a fixed point, at the end of a pin, on which the needle hangs by a single, jewelled socket.
Industry:Earth science
