Solar Definitions for Land Surveyors

solar-1 Of or having to do with the sun. 2 Produced by or coming from the sun; solar energy. 3 Depending upon the sun’s light or energy; solar heating. 4 Fixed or measured by the Earth’s motion with relation to the sun; mean solar time. 5 [ASTROLOGY] Under the influence of the sun.

solar attachment—An auxiliary instrument which may be attached to a engineer’s transit, thus permitting its use as a solar compass.

solar chart—A chart graduated according to the principles of the sun dial, but much more accurate. It is designed to be placed on a plane table or other level surface to determine the direction of true North relative to the direction of a shadow cast by a gnomon in sunlight.

solar circle—A circle in the reticle of the transit telescope equal in size to the image of the sun whose radius is 15′ 45″, spaced for the sun semi-diameter on July 1, which is the approximate minimum for the year; there is a slight noticeable overlap of the image from about September to April. In making observations, the image and the circle are taken concentrically to result in horizontal and vertical angles to the sun’s center.

solar compass—See compass, solar.

solar-observation method (of determining azimuth)—Determination of astronomic azimuth by measuring the sun’s angular elevation, the angle of the marker from the sun at that instant and the time of measurement. The azimuth of the sun is added to the measured angle of the marker with respect to the sun to get the azimuth of the marker.

solar time—See time, solar; day.

solar transit—A regular transit with a solar attachment which affects the instantaneous mechanical solution of the astronomical triangle (sun-zenith-pole) and permits the establishment and surveying of the astronomic meridian or astronomic parallel directly by observation.

Source: NSPS “Definitions of Surveying and Related Terms“, used with permission.

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