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Eng ID Term Definition
2301
horizon: sensible
That circle of the CELESTIAL SPHERE formed by the inter­section of the CELESTIAL SPHERE and a plane through any point, such as the eye of an... more
That circle of the CELESTIAL SPHERE formed by the inter­section of the CELESTIAL SPHERE and a plane through any point, such as the eye of an observer, and perpen­dicular to the zenith-nadir line.
2302
horizon: true
In PHOTOGRAM­METRY, a horizontal plane passing through a point of vision or PERSPECTIVE CENTRE. The APPARENT HORIZON ap­proximates the true ... more
In PHOTOGRAM­METRY, a horizontal plane passing through a point of vision or PERSPECTIVE CENTRE. The APPARENT HORIZON ap­proximates the true horizon only when the point of vision is very close to SEA LEVEL.
2303
horizon: visible (or local)
See HORIZON: APPARENT.
2304
horizon glass
That glass of a MARINE SEXTANT, atta­ched to the frame, through which the HORIZON is observed. That half of this glass nearer the frame is s... more
That glass of a MARINE SEXTANT, atta­ched to the frame, through which the HORIZON is observed. That half of this glass nearer the frame is silvered to form the HORIZON MIRROR for reflecting the IMAGE of a CELESTIAL BODY; the other half is clear.
2305
horizon line
See HORIZON TRACE.
2306
horizon mirror
The mirror part of the HORIZON GLASS. The expression is sometimes used somewhat loosely to refer to the HORIZON GLASS.
2307
horizon photograph
In AERIAL PHOTOGRAPHY, a PHOTO­GRAPH of the HORIZON, taken simultaneously with a VERTICAL PHOTOGRAPH and used to determine the RELATIVE TILT... more
In AERIAL PHOTOGRAPHY, a PHOTO­GRAPH of the HORIZON, taken simultaneously with a VERTICAL PHOTOGRAPH and used to determine the RELATIVE TILT between adjacent VERTICAL PHOTOGRAPHS.
2308
horizon shade
One of the pivoted coloured glasses which can be swung before the HORIZON GLASS of a SEXTANT to regulate the intensity of light.
2309
horizon system of coordinates
A set of CELESTIAL COORDINATES based on the CELESTIAL HORIZON as the PRIMARY GREAT CIRCLE; usually ALTITUDE and AZIMUTH or AZIMUTH ANGLE.
2310
horizontal
(adj). Parallel to the plane of the HORIZON; perpendicular to the DIRECTION OF GRAVITY.
2311
horizontal axis
See AXIS.
2312
horizontal circle
See CIRCLE.
2313
horizontal control
See CONTROL.
2314
horizontal control datum
The position on the SPHEROID OF REFERENCE assigned to the HORIZONTAL CONTROL (TRI­AN­GULATION and TRAVERSE) of an area and defined by (1) th... more
The position on the SPHEROID OF REFERENCE assigned to the HORIZONTAL CONTROL (TRI­AN­GULATION and TRAVERSE) of an area and defined by (1) the POSITION (LATITUDE and LONGITUDE) of one selected STATION in the area, and (2) the AZIMUTH from the selected STATION to an adjoining STATION. See also DATUM: GEODETIC.
2315
horizontal coplane
See COPLANE: BASAL.
2316
horizontal dilution of precision (HDOP)
See DILUTION OF PRECISION.
2317
horizontal force instrument
See VIBRATING NEEDLE.
2318
horizontal intensity of the earth's magnetic field
The strength of the horizontal component of the EAR­TH'S MAGNETIC FIELD.
2319
horizontal parallax
See PARALLAX.
2320
horizontal photograph
See PHOTOGRAPH.