Showing posts from March, 2013

Field Astronomy

Field astronomy deals with the determination of the relative positions of the celestial bodies by taking the astronomical observations. Related terms: 1. Celestial sphere: If we assume the space to be a sphere having the earth as its center and all the star lying on its surface, or studded in it. The celestial sphere can be of few kilometers to many thousand kilometer. 2. Zenith and Nadir : These are two points on the celestial sphere opposite to each other and lying above and below the observer. Zenith is the point on the celestial sphere, above the head of the observer and Zenith is the point on the celestial sphere below the observer. Alternatively, these are the points of intersection of the plumb line(drawn through the point of observation) with the celestial sphere.
3.Terrestrial poles and equator: Terrestrial poles are the points of intersection of the axis of rotation of the earth with the earth sphere, and the terrestrial equator is the great circle of the earth which is pe…

Errors -Surveying

Error:- The difference between the observed value and the true value is known as error. There are three types of errors which occurs while we do the surveying: Mistakes: These are the errors which occur due to the inexperience, inattention, carelessness or due to lack of judgement or poor jusdgement. If mistakes are not found then they may effect the result to a great extent. Systematic errors: These are the errors which follow a system when they occur, and they have the same nature whenever they occur. They can be eliminated by testing the instruments before they are used or by applied the necessary correction, by using the mathematical formulae after the error is known. Accidental errors: These are the kind of errors which occur accidentally and can of any nature positive or negative. These are the errors which are byond the human control and can not be calculated to their true value, but only we can apply the theory of the probability to calculate them. Weight of an ob…