Question 1615Navigation General

The correct answer is C) vertical circle of the body. The azimuth angle is measured from the principal vertical circle (a great circle passing through the zenith and the north and south points of the horizon) to the vertical circle of the celestial body being observed. The vertical circle of a celestial body is the great circle passing through the zenith and the celestial body. This is the standard definition of azimuth in celestial navigation. The other options are incorrect because the azimuth is not measured relative to the local celestial meridian (A), the Greenwich celestial meridian (B), or the hour circle of the body (D). Those are different reference circles used in celestial navigation, but not the one used to define azimuth.