- 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 magnetism displayed by the south-seeking end of a freely suspended magnet. This is the magnetism of the Earth's northern magnetic pole.
Industry:Earth science
Photography from the Earth's surface. In particular, in photogrammetry, photography on and of the Earth's surface.
Industry:Earth science
(1) The acute angle ε between the ecliptic and the celestial equator. (2) The acute angle between the pole of the ecliptic and the mean north celestial pole. It is given as a function of time by ε = 23<sup>o</sup> 27' 08.26"= 0.4684" T - 0.000006" T², in which T is the time in tropical years since 1900.0. The obliquity of the ecliptic is therefore about 23.45<sup>o</sup> and is decreasing at the rate of about ½" per year.
Industry:Earth science
On old styles of surveyors' compasses, a scale numbered 1 to 16, with a pointer turned by a milled knob to keep track of the outs.
Industry:Earth science
A mounting permitting the instrument to be rotated about a fixed axis (right ascension axis or polar axis) parallel to the Earth's axis of rotation and/or about an axis (declination axis) perpendicular to the polar axis.
Industry:Earth science
Photography in which the camera takes a picture of the image cast upon a screen by a cathode-ray tube, as in radar, television, etc. or other light-emitting display.
Industry:Earth science
A plane coordinate system set up at the convenience of the surveyor to be used locally. The axes are usually defined so that all points of the survey are in the first quadrant. The y-axis is usually directed northward.
Industry:Earth science
(1) To make a drawing by placing points on a sheet according to their coordinates. (2) To place data from a survey upon a map. In the past, no clearly defined difference existed between plat and plot. It has been suggested that a difference be established by limiting the term plat to the graphical representation of a survey (i.,e., the map), and plot (in the geodetic sense) to the cartographic operations involved in constructing a map.
Industry:Earth science
A map projection from the hemisphere to a disk, as defined by the equations<br>
Industry:Earth science
(1) The deviation of an orbit from some orbit taken as standard, i.e., a perturbation of an orbit. In particular, the deviation from a Keplerian orbit. It is usually referred to simply as a perturbation if the meaning is clear. In celestial mechanics, the forces causing deviations from a Keplerian orbit are called perturbing forces or disturbing forces. The principal perturbations of an orbit of a satellite of the Earth are caused by the non-central part of the Earth's gravitational field, the gravitational attractions of the Sun and Moon, atmospheric drag, pressure of solar radiation and the Earth's magnetic field. The principal perturbations of the Moon's orbit are caused by the gravitational attraction of the other planets and of the Sun. The principal perturbations of the Earth's orbit are caused by the gravitational attraction of the other planets and of the Moon. Perturbations are usually calculated as quantities to be added to the coordinates of the standard orbit to obtain the precise coordinates. (2) A force causing deviations from a Keplerian or other standard orbit. This usage is best avoided, because it makes the term ambiguous.
Industry:Earth science
