celestial navigation | Concept of celestial sphere | astro navigation | Systems of Coordinates Equatorial System | part 2
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Systems of Coordinates
1stEquatorial System of Coordinates
Local Hour Angle (L.H.A)
Is the arc on the equinoctial or the angle at the pole, from the upper observer’s meridian, to the meridian of the heavenly body, measuredwestward, from 0˚ to 360˚.
Is the arc on the meridian of the heavenly body, from the equinoctial, to the heavenly body, measurednorth or south, from 0 to 90˚.
Polar Distance (P. D)
Is the arc on the meridian of the heavenly body, from the elevated pole, to the heavenly body, measured 0˚ to 180˚.
Component of 1st equatorial system of coordinates
L.H.A and Dec. / P.D
the relation between Dec. And P.D
P.D = 90 – Dec if Lat & Dec Same name
P.D = 90 + Dec if Lat & Dec Contrary name
Calculate the Polar Distance of the heavenly body where:
Latitude of the observer 40 N, Declination of H.B 30 S
P.D = 90 + Dec
P.D = 90 + 30
P.D = 120